Building Pathology Flashcards

Question

What is carbonation? How would you treat it?

Answer 1

Carbonation occurs when the alkaline elements of the concrete react with the atmospheric carbon dioxide creating calcium carbonate which lowers the PH level of the concrete and therefore reduces the passivity of the concrete. It will cause gradual neutralisation of the alkalinity from the surface inwards. Should there not be adequate coverage of steel reinforcement within the concrete, carbon dioxide can react with the re-bar and cause corrosion and spalling of the overlying concrete – then allows further moisture ingress and corrosion. Should have 50mm concrete cover, can be as little as 10mm in older high rise flats! Test: drill 10mm diameter holes into concrete and break out section of concrete between. Treat freshly exposed concrete with phenolphthalein (concrete will turn pink if un-carbonated). Rectify: Hack off loose / defective concrete, grit blast all corrosion to steel, apply proprietary bar primer and patch repair area with mortar repair system e.g SIKA Ferrogard.

Answer 2

A chemical reaction affecting concrete causing it to expand and crack. Externally this is due to the penetration of sulphates in solution (usually carried in groundwater) coming into contact with the concrete. Internally, this can be due to introduction of sulphates into concrete during the mixing process e.g sulphates in the hardcore beneath a concrete floor slab. Can affect foundations and concrete floor slabs (concrete floor slabs are now required to be separated from the ground by polythene sheeting under building regs). For foundations that may be susceptible you can spec Type 2 Portland cement (moderate resistance to sulphates) or Type 4 /5 cement (for very high resistance).

Answer 3

Located in brickwork, blockwork, render and concrete. Heave in concrete slabs and displacement of adjacent masonry In dwellings with timber floors, the sleeper walls may become displaced causing deflection in floors Cracking Spalling Loss of strength Increase surface area for further attack Friable Edges and corners susceptible Upwards bowing coupled with map pattern cracking and possibly displacement of brickwork at slab level are common indicators. Visual indicators of affected concrete may be the existence of flaky or crumbly concrete

Answer 4

BRE Digest 405

Answer 5

BRE Digest 245.

Answer 6

BRE Digest 345

Answer 7

BRE Digest 299

Answer 8

Requires hardwood or softwood as food source. Requires moisture content of 20% or higher for a sustained period. Damp, still air for sustained periods.

Answer 9

A herbaceous perennial plant that is a non-native, invasive species in the UK. First introduced for ornamental purposes in the mid 1825 century but now very invasive due to lack of enemies such as insects, bacteria and fungi that are only present in it’s country of origin. JK grows through spreading of rhizomes laterally. Causes circa. £165m per year. Commonly found around public waterways and railway tracks.

Answer 10

Green, shield shaped leaves with flattened bases. Hollow, bamboo-like stem which is light green with speckled red colouration. Small, clustered creamy-white flowers. Thick and extensive rhizomes which are orangey-yellow internally.

Answer 11

Rhizomes can exploit cracks and structural weaknesses in building fabric or existing cracks causing progressive cracking and loss of structural integrity. This can occur in foundations, walls, retaining walls, hardstandings (through movement joints and weaknesses in incorrectly laid hardstandings). Rhizomes can also physically move and block underground services such as drainage and water pipework in addition to affecting buried cables. Can prevent homebuyers from gaining a mortgage from a preferred lender and some do not cover JK. Can cause diminution in land / property value. Can spread very easily to neighbouring property - 0.02g of rhizome needed to allow regrowth.

Answer 12

Spring: emerging stems that can range from green to red and purple with rolled leaves. Late summer / early Autumn: Creamy-white flowers form in drooping clusters. Autumn / winter: Stems only present and turn various shades of brown, sometimes with orange tinge.

Answer 13

Excavation and disposal: Excavation can extend up to 3m vertically and 7m horizontally from the above ground growth. Is then taken to appropriately licenced waste management facility. Onsite burial and encapsulation with membranes: Excavated then buried on site, if can’t be covered with 5m of overburden a specialist root membrane must be installed or the Japanese knotweed will be completely encased with root barrier if it cannot be completely buried. Chemical control with use of specialist herbicides applied by mixture of stem injection and localised spraying. Biological control: introduction of a ‘pest’ species that will attack the JK. Trials currently being undertaken with Japanese sap sucking insects. However will not control infestation on its own.

Answer 14

Wildlife and Countryside Act 1981 - it is an offence to plant of otherwise cause Japanese Knotweed to grow in the wild. The Duty of Care Regulations 1991 - Japanese Knotweed is classed as controlled waste and therefore owners owe a duty of care when handling and disposing of it.

Answer 15

Offence to plant or grow it. Illegal to cause spread. Classed as controlled waste and requires a licence to dispose at licensed sites.

Answer 16

Herbicidal treatment: + Cost effective. + Carried out in situ - less risk of accidental spread. + Quickly reduces ability of JK to spread and impact structures. - Can take years to complete treatment (3 year course then monitoring). - Not appropriate where development is planned - will cause spreading. - Continued monitoring required 2 years post treatment to confirm rectification. Burial: + Work can continue immediately after burial. + Quick. - May not be possible to burry on site - buried services etc. - Not possible if water table is high. - Rhizomes can be accidently spread. Excavation and offsite disposal: + Quickly removes JK. + No restrictions left on site. + Works can continue immediately. - Expensive. - Reduces valuable landfill capacity. - Increased risk of spread. - Should be used as a last resort measure.

Answer 17

Explained that the client had a statutory obligation to prevent its’ further spread under the Wildlife and Countryside Act 1981. Stated the implications if left to spread - could spread to where site incoming water and outgoing drainage were and near security hut. Recommended that although I had identified it, a Japanese Knotweed specialist surveyor should be instructed to map the area and provide recommended remedial options and reasoned professional advise. Herbicidal treatment was chosen on the basis that: Water table was particularly high on site - couldnt burry. Chemical treatment would take longer but reduced chance of disturbance and spread of JK. Land was an existing site and not going to be developed in the foreseeable. 10 year guarantee was issued - this was a condition of the new incoming tenant looking to let the property on a 10 year FRI lease.

Answer 18

Whereby the level if moisture inside a building reaches a level that causes building defects such as staining of decorative finishes, mould growth, frost damage and sulphate attack.

Answer 19

The use of a protimeter / moisture meter or a Speedy Carbide Meter can be used to establish the moisture content of walls, and the level of damp occurring.

Answer 20

Condensation. Rising damp Penetrating damp

Answer 21

It is the result of water being drawn up through porous masonry from wet ground via capillary action. It can be detected by horizontal tide marks up to 1.3m in height (any further vertical movement is prevented by gravity), blown plaster and spoilt decorative finishes. Causes include: 1. No DPC. 2. DPC bridged (render, soil, raised external paving, covering, removed or blocked vents to suspended floors, poor underfloor ventilation). Remedies include: 1. Installation of DPC. 2. Electro-osmotic damp proof course. 3. Chemical injected DPC. 4. Increase internal ventilation and heating.

Answer 22

Horizontal lines observed on decorative finishes or building fabrics which show the vertical extent of rising damp. Below which there will be discolouration and general darkness and might be general deterioration to decorative finishes. Hydroscopic salts tend to be concentrated in the tide mark which originate from the ground and are left after evaporation of the ground water.

Answer 23

Occurs when water penetrates the a building’s envelope. Causes can include: Saturation of walls exposed to prevailing winds, usually south or south-westerly. Defects with masonry walls that allow penetration e.g damaged masonry and lack of pointing. Leaking rainwater goods: can saturate the masonry leading to frost damage which then allows water ingress, can also enter into the loft space if sarkiing is too short and guttering overflows due to blockage. Defective or missing cavity trays. Failed roof coverings (slipped tiles and defective flat roof coverings). Remedy includes: 1. Find and rectify the source of the leak. 2. Promote rapid drying (through heating and ventilation or dehumidifier and restricted ventilation).

Answer 24

The process whereby water condenses from water vapour to liquid water when the temperature of air containing the water drops to, or below the dew point (temp at which air becomes saturated with water vapour). There are two forms of condensation: 1. Interstitial: Occurs within the structure at interfaces between materials and tends to be hidden by construction and surface finishes. 2. Surface: Occurs on surfaces and therefore easier to observe.

Answer 25

Surface condensation Causes: 1. Cold internal surfaces such as external walls, single glazed windows, cold-water pipes, wall-to-floor junctions, lintels and window reveals. 2. Large amount of excess moisture produced from human activity including cooking in kitchens, bathing, drying clothes inside. This moisture condenses in the rooms where the activities occur but also migrates to where vapour pressure is reduced in areas such as unheated rooms. 3. Excess moisture from unvented or defective flues from paraffin or butane heaters or tumble driers. Affects: 1. Mould growth - usually more prevalent to areas with restricted air movement such as behind furniture or inside cupboards. 2. Damp patches and spoiling of decorative finishes. Remedy: Mixture of increasing heating and ventilation. Modifying human behaviour - heat all rooms of the property and reduce activity that causes excess moisture - shorter showers, dry clothes outside etc. Fix any defective flues. Increase insulation. Install windows with trickle vents.

Answer 26

Issues: Can cause dampening of insulation materials which can lead to reduction in performance and eventual physical deterioration. If forming against timbers, can promote rot and insect attack. Rectification: Changing of the building detail if there is an inherent defect. Replacement of insulation if penetrated such as in a cold roof build up - insulation penetrated by fixings, vapour then passes through vapour control barrier and then into the very cold roof void allowing condensation to form on structural timbers.

Answer 27

They are put in roofs and some cavity walls to prevent moist air penetrating to a point where it might need its dew point temperature and cause interstitial condensation.

Answer 28

Penetrating damp — moisture gets into the building because there is a porous bridge transferring moisture by capillary action from the external face of the walls to the internal face of the walls. Could be a single skin of masonry, water trapped behind render, mortar snots on cavity ties etc. Or there is a hole in the roof which allows moisture in through and it gets to the ceiling due to the force of gravity. I would identify it based on its location further investigation of the cause of the moisture. Rising damp — Moisture rising up the wall from the ground due to capillary action normally up to a maximum of lm high tide marks. Identify through a visual inspection of its location and extent and also use moisture meter to confirm that the moisture content starts off high and gets lower before cutting off at approx 1 m. Identify if there is a DPC is something bridging that DPC. Ensure there are no other possible causes. Condensation — Hot moist air hits a cold surface and condenses causing the surface to absorb the moisture which encourages staining and mildew growth. Identify it through the distinctive mildew, the location poorly ventilated areas with high humidity, kitchens, bathrooms, bedrooms, rooms used for drying clothes.

Answer 29

Blocked air vents to ground floors, causing dry rot Failed or lack of damp proof course – rising dampness, penetrating damp, efflorescence on plaster, decay to skirtings Delamination of brick skins – bulging of brickwork Over notching of floor joists for retrofit of services – deflection of floors, reduction in load bearing capacity Poorly fitting sash windows, risk of decay within window reveals, water penetration beneath sub-sills, draughty or dangerous operation, decay in concealed areas, lack of security Roof covered with concrete interlocking tiles – overloading of roof structure, bowing of rafters and purlins, roof spread Settlement of bay windows – internal cosmetic damage, distortion in load-bearing elements Wall tie failure (particularly in black ash mortar) Heave or subsidence of shallow foundations Nail sickness – ferrous nails corroded

Answer 30

900mm centres horizontally 450mm centres vertically 300mm away from windows

Answer 31

cavitys built before 1981 due to the life expectancy of galvanising. Until 1970 twisted butterfly ties were also still in use.

Answer 32

Use a metal detector or boroscope to determine location. remove defective and replace with new by drilling into the wall

Answer 33

Visible on brickwork and caused by soluble salts being brought to the surface as the wall dries out. Shown as White Staining

Answer 34

Water paths through parapets, hidden valleys and gutters Springy floors resulting from decaying timber floor joists. mainly caused by poor cross-ventilation. heel drop test to test the springy floor. Rotten or stuck sash windows Blocked internal gutters. Damp penetration in solid walls Corroded cast iron railings bursting stonework Bowed brick walls, caused by the practice of lightly bonding high-quality facing bricks in with poorer quality bricks of the main wall, unbonded party walls and front walls and decaying coursed timbers buried in walls Failure in roof trusses caused when roof ties rot and begin to spread. Dislodged joists and ridges caused by bomb blast damage. Leaning chimneys/over-tall stacks/damp penetration via stacks Perforated lead work or splitting caused by over-beating or poor maintenance Missing or badly altered load-bearing timber partitions Damp basements Failure of timber lintels Poorly applied or painted stucco limiting water evaporation from walls Downpipes decanting on to lower roofs from roofs above, causing temporary flooding in heavy rainfall

Answer 35

A combination of erosion, acid attack and salt crystallisation are liable to cause a chimney to lean (see illustration). The BRE Good Repair Guide says any chimney that leans more than 1nnnn in 100mm is unsafe

Answer 36

Sulphate attack can cause serious damage to brickwork and concrete by creating expansive force that are, or can be, sufficient to disrupt mortar and create significant expansion, bowing and cracking of concrete floor slabs together with related collateral damage. In some subsoil there can be a problem with sulphate attack. It occurs when the fill material (hardcore) beneath the slab contains sulphates and these migrate into the concrete. The sulphates react with the concrete causing it to expand. Calcium, magnesium and sodium sulphates occur naturally in some clays and other sub soils The sulphates dissolve in the groundwater and permeate the concrete. This leads to an aggressive chemical reaction between the sulphates in solution and one of the chemicals in the cement. The resulting compound expands rapidly as it forms and this can crack the foundation concrete. If sulphate attack is a possibility it is wise to use sulphate resisting cement.

Answer 37

Spore Hyphae Mycelium Fruiting Body

Answer 38

A generic term that is used to commonly describe the larva stage of wood boring beetles. A number of insects, mainly beetles, are able to use wood as a food source and some of them can cause serious damage to building timbers.

Answer 39

COMMON FURNITURE BEETLE (WOODWORM) 3-5m long, dull brown Lines of pits on wings Found on or around damaged timber LATE MARCH – EARLY AUGUST (particularly warm weather. Softwood, European hardwoods 1-2mm dia. Circular flight holes Flight holes random orientation, mainly in direction of grain. Bore dust, cream coloured, lemon shaped pellets. Life cycle 2-5 years * LONG HORN BEETLE Adult 10-12mm, black or dull brown. Sapwood or softwoods particularly roof timbers. South-west of London mainly surrey. Flight holes, few large oval, 6-10mm largest dimension. JULY to OCTOBER Cream coloured, sausage shaped. * DEATHWATCH 6-9mm long, chocolate brown MARCH to JUNE Bore dust, disc shaped cream pellets Flight holes circular 3mm diameter Mostly oak and elm (hardwoods) * WEEVIL 3-5mm long, brownish black. Distinctive long snout. All year around. Flight holes, small ragged, 1mm diameter. Decayed softwood and hardwoods in damp conditions. Mostly found in below ground conditions.

Answer 40

Asbestos Calcium chlorides Calcium silicate bricks CFC’s Formaldehyde HAC (High Alumina Cement) Hollow clay pot floors Lead Nickel sulphides

Answer 41

Asbestos CFC’s (Chlorofluorocarbons) (think air conditioning refrigerants) HCFC’s (R22. Banned from January 2015) Crystalline Silica (Found in building materials. Dust can result in silicosis (lung disease)). Formaldehyde (Carcinogenic material used in foam and timber-based building materials) Lead (used in roofing, waterpipes and paint) (Carcinogenic and teratogenic) Machine Made Mineral Fibres (MMMF) (Respiratory issues) Continuous filament (glass wool) Insulation (rock wool or slag wool) Ceramic Fibre Special purpose fibre - Coal Tar - Anphrax Horse Hair

Answer 42

Used as a permanent shuttering. Formwork is used to contain concrete in order to mould it to the required dims and to support it until it can support itself. It may be left in place for the lifetime of the building.

Answer 43

Concrete does not adequately get compacted. Risk of poor cover to the steel and hence loss of durability, possible reduction in strength, and loss of fire resistance. Voiding and honey combing due to vibrations. Poor bond or failed bond between the wood wool and the hardened concrete. Buildings constructed from 1950 to the mid-1970s are most likely to be affected by this form of construction. If permanent shuttering is discovered, intrusive investigations may be needed to determine the adequacy of concrete cover to the steel reinforcement. If voiding is present, the affected area can be exposed and repaired using hand-fixed concrete repair methods or, if over a larger area, sprayed concrete.

Answer 44

Concrete Carbonation - co2 in air HAC Alkali Silica Reaction Chloride Attack - chloride attacks steel Sulphate Attack - sulphates in soil

Answer 45

A generic term that is used to commonly describe the larva stage of wood boring beetles. A number of insects, mainly beetles, are able to use wood as a food source and some of them can cause serious damage to building timbers

Answer 46

Occurs in glass production. Microscopic imperfections in the glass. When the glass is tempered, the nickel sulphide inclusions do not return to the normal low-temp state for several years and expands in the process which can cause cracks with no obvious cause.

Answer 47

Chrysolite – most common asbestos in buildings. Corrugated asbestos cement sheets. Amosite – found in fire retardant materials (insulating board) Crocidolite – pipe insulation, plastics, cement products.

Answer 48

Features include shrunken wood with cuboidal shapes. Cotton wool type mycelium on the surface. Timber crumbles under finger. Fruiting bodies are red/brown in colour and pancake shaped. Identify the rot and where it is at its worst. Remove the cause and strengthen the joists as required or fully replace. If the dry rot has passed through the masonry, this will need sterilisation too.

Answer 49

When used as permanent shuttering for concrete, it may lead to grout loss, honeycombing or voids which can reduce fire resistance, corrosion protection and loss of strength. It is adequate for use in flat roof decking.

Answer 50

Asbestos – Fiberous material used for a variety of reasons from roof sheets to insulation and fire stopping. It is carcinogenic and needs to be removed if there is a risk of release of fibres. Lead – Risk of lead poisoning when used for pipes or paint. Contaminates drinking water and risk of inhalation of paint dust or potentially ingested when children chew on painted products. Machine Made Mineral Fibres – Potential Carcinogenic. The evidence leads to show there is a high risk and should be treated as such but has not yet been proved. Wood Wool Slabs – When used as permanent shuttering for concrete, it may lead to grout loss and inadequate coverage of steels which leads to inadequate fire protection. If used for roof decking, it is not considered deleterious. Calcium Silicate Bricks – Shrinks after construction with further movement from wetting. Thermal movement more likely than with clay bricks. Construction details must allow for movement and if designed and used correctly, performs well. High Alumina Cement – Gives high early strength and used in maritime buildings. Porosity is increased and resistance to chemical attack is reduced. Where water and chemicals are present in the mix, it can lead to the concrete becoming friable and lead to loss of strength.

Answer 51

Any material that is harmful to health, safety, environment, not suitable for their purpose or pose a risk for where it is used.

Answer 52

Crazing - Surface crazing caused by lack of protection from UV exposure. No treatment is required if in small localised patches but should be monitored. Ponding - If the gradient is not sufficient and there are dips in the roof finish, it can lead to pools of water. It can lead to water ingress if there is a gap in the roof finish. Thermal Movement Cracks and splits can occur when there is thermal movement between the substrate and membrane. Usually requires localised repair to the area around the crack. Blistering - Caused when water vapour beneath the roof finish increases. The source of moisture should be traced and the blister opened and allowed to dry before patch repairing. Flashing and Falls around openings- Defective lead from deterioration or poor workmanship around openings causing water ingress. Depending on the issue with the lead, there are different repairs. People - Punctures caused by people from impact damage. Cracks and tears along the line of joists - Caused by thermal movement or saturation of insulation or sagging decking. Repaired by cutting felt back and allowing it to dry before patching over.”

Answer 53

Thermal movement refers to the expansion and contraction of building materials in response to temperature changes. When materials heat up, they expand; when they cool down, they contract. This movement can cause various issues in buildings, such as cracking, warping, or structural stress

Answer 54

1:40. Best practice more like 1:60

Answer 55

As they are not protected with a DPM when they comes into contact with a water source they expand and can transfer this up into the slab above

Answer 56

That as a roof ages the fixings which are often iron nails start to fail resulting in tile or slate slippage especially in windy weather conditions. Replace existing iron nails with copper nails, these do not corrode.

Answer 57

House Longhorn Beetle - only found in Surrey, Berkshire and Hampshire.

Answer 58

Incorrect application of cement pointing: In solid wall buildings, if lime based mortar is replaced with cement mortar the mortar joints cannot release the interstitial moisture within the wall, it therefore is released through the brickwork which leads to spalling due to excess moisture release and makes the bricks more susceptible to freeze thaw as they have a higher moisture content. Freeze thaw: Water absorbed through the porous surface of the bricks and then expands upon freezing. Crystallisation of salts (cryptoflorescence): this occurs just below the surface of the bricks leading to spalling. Occurs from large build up of salts and usually occurs where older, weaker bricks are re-used inappropriately in areas of excess dampness (at ground level which is susceptible to splashback - should use engineering bricks).

Answer 59

Carbide meter: Sample of mortar, plaster or brick taken and weighed. Sample then placed in one chamber, a weighed amount of calcium carbide powder is placed in a separate chamber. Container then shaken to allow mixing of two materials. The amount of acetylene gas produced indicates the amount of moisture present. Pros: accurate. Disadvantages: intrusive, more time consuming that protimeter. Moisture meter: Measures level of conductivity, water has high conductivity so increases the reading when present. Pros: Quick, non-intrusive (relatively). Disadvantages: Calibrated for timber, can give false high readings from highly conductive materials such as salts, foil backed plasterboard and black ash mortar. Deep wall probe: Essentially a long protimeter than can measure conductivity deeper within the wall.

Answer 60

Dead load: load imposed by the structure itself. Live load: load imposed by occupants and objects in a structure. Environmental load: load imposed by rainfall, snow and wind.

Answer 61

Giant Hogweed. Horse tail.

Answer 62

Property Care Association Code of Practice.

Answer 63

Dig and dump (excavation of the plant and roots) JK infested soil excavated (up to 3m vertically and 7m horizontally from the area of growth), removed off site and disposed in an appropriately licenced waste management facility as it is classed as controlled waste under the Environmental Protection Act 1990. Benefits: quick, no restrictions on site for development, works can continue on site immediately. Drawbacks: Expensive (£70 per tonne), reduced valuable landfill capacity (should be last resort), increases risk of spread (disturbing the plant through excavation) On-site burial Trench is excavated on the site in suitable location and JK then excavated and buried in the trench which will need to have at least 5m of overburden. Unless JK can be buried with 5m of overburden then a specialist root barrier membrane must be used to partly or full encapsulate the JK. Area is then monitored for at least two successive growth seasons and treated with herbicides if needed. Benefits: More cost effective than dig and dump, works can continue immediately, quick to remove. Drawbacks: Need suitable set aside area where the JK will not be disturbed, can’t be used if water table is high (allows distribution of JK into waterways), if root barrier used it needs to be installed correctly as any weaknesses / tears can be exploited by JK, JK can be accidently spread during excavation. Herbicidal treatment Herbicides applied to JK usually combined application of spraying and stem injection. Benefits: Cost effective, can be carried out in situ (less risk of spread), quickly reduces spread and ability to impact structures, can be used on restricted sites that don’t have a set aside area. Drawbacks: JK remains in situ do could be disturbed and spread (particularly if works being carried out), not appropriate for sites where there is planned development (excavation), take several years to achieve complete eradication with two years of monitoring to ensure growth has ceased. Other options: Biological control - testing being undertaken - still not used. Screening / sifting - JK excavated along with soil which is then sifted to separate rhizomes which are disposed of appropriately, the soil is then screened and stored on site in a suitable location, treated with herbicide and monitored.

Answer 64

Cold roofs: As the roof void is cold there can be issued with interstitial condensation as warm air from inside the building enters the unheated roof space allowing condensation to form on the timber roof joists and deck - this make them susceptible to rot and therefore structural failure eventually. Require vented 50mm gap between bottom of roof deck and top of insulation to try and prevent. More complicated to construct - insulation between the joists rather than just on top of roof. Greater chance of thermal bridging - ceiling joists are not insulated. Benefit: as insulation is between joists there is no change to roof height - this could affect roof height relative to the parapet walls - may need to extent them etc Warm roofs: Easier to install. Can be retrofitted. Less chance of thermal bridging. Drawback - external roof height will be raised Better thermal performance

Answer 65

It was clear to see that the roof covering had failed in numerous areas and water could be seen dripping through the underside of the roof deck. There was also staining and areas of plasterboard soffit that were saturated and had fallen in isolated areas. Rising damp would have been localised to the walls and tide marks would have likely been present to a height of circa 1.3m with spoilt decorative finishes, staining and blown plaster below. Condensation was present to the internal windows but I believe this was a result of the building being unheated, unventilated and having excess water vapour from the penetrating damp.

Answer 66

I advised my client that if the JK was not treated it could continue to spread and damage the adjacent hardstanding and security hut by exploiting structural weaknesses and causing cracking in addition to causing cracking of mains water and drainage pipework which I know were in close proximity to the infested area. I also advised that the client that under the Wildlife and Countryside Act 1981 they were obligated to control its spread and prevent spread onto neighbouring properties. I then considered the potential remedial options but recommended that herbicidal treatment should be utilised on the basis that the site had a high water table and no suitable area to dispose of the JK to allow on site burial and also that excavation should be used as a last resort, would be considerably more expensive and may lead to further spread of the JK. I advised that the client that as JK had been identified, the client should instruct a JK contractor to map the entire site to confirm the extent of the growth and make sure there were no other areas of infestation. I also advised that the client should ensure that they had a 10-year guarantee with the treatment to give comfort to the incoming tenant on a 10 year FRI-lease.

Answer 67

Environmental matters, i.e. trees in close proximity Neighbouring dwellings Engineers structural survey CCTV Drainage survey

Answer 68

The staining and deterioration to the internal plasterboard / decorative finishes was patchy and concentrated in numerous areas along the length of the elevation. If it was rising damp I would expect to see a linear tide line around 1.3 m max height. I was lucky that the second time that I visited the property there had been a sustained period of rainfall and I could see that the areas of staining observed previously had darken.

Answer 69

Solid walls: leaking mortar joints (need to be raked out to a depth equivalent to their height and then repointed), masonry water repellent to less exposed elevations, defective jointing details around windows etc. Cavity walls: Rarer but could have bridging of cavity by wall cavity ties sloping inwards (will see regular spots of ingress), bridging of the cavity wall by it being blocked above the DPC from mortar droppings and other debris, missing cavity trays.

Answer 70

Residential Georgian Water ingress through parapet walls and valley gutter details. Missing or poorly altered load-bearing timber partitions. Failure of roof trusses Poorly applied or painted stucco limiting water evaporation from walls Rotten or stuck sash windows Victorian Defective slates and nail sickness. Deflection of roof timbers caused by installation of heavier concrete tiles (cheap). Blocked air vents to suspended timber floors from removal or raising of external pavement level. Lack of lateral support between terrace houses (known as the book end effect); joists run parallel with part walls. Modular - Post Second World War Use of asbestos sheets to roofs. Corrosion of steel frames used. Alkali Silica Reaction affecting concrete frames (gel General housing (modern) Cracking and movement of walls due to timber frame being wet and then shrinking once dried out. Heave / subsidence. Industrial Impact damaged cladding. Cut edge corrosion. UV degraded roof lights. Asbestos roof sheets. Office Buildings (60s-80s) Hollow clay pot floors - can exhibit loss or strength due to honeycombing of the structural concrete ribs of the floor system which reduces structural integrity and fire stopping capabilities. Incorrect removal of topping screed if structural to gain floor height can lead to structural failure. Wood wool cement board - WWCB is formed of softwood shavings which are coated and bounded by Portland cement. WWCB was commonly used as permanent shuttering in flat slab or ribbed reinforced concrete floors. There is risk of poor concrete cover to the steel structural members therefore reduces durability, structural integrity and fire resistance. If discovered the shuttering be removed to determine coverage and parch repairs undertaken by hand if necessary.

Answer 71

Found in early 20th century load bearing steel framed buildings clad externally with stone, brick and terracotta that is notched around the steel frame and then the void filled with low grade mortar. Corrosion of the steel frame due to oxygen and moisture causes corrosion and expansion and with no void space causes cracking of the mortar and overlying cladding. Can usually diagnose from cracks delineating the frame. 2 main ways to rectify: Exposing the steel, cleaning it and protecting it and then create a void around steel frame to allow movement. Use cathodic protection: system relies on concealment of discrete anodes into the stone joints and electrical connection to the steel frame and the introduction of an electric current to reverse the corrosion process. Requires detailed design to ensure harmful currents arnt produced and maintenance.

Answer 72

Settlement is caused by the building drying out following construction - usually seen internally Subsidence is caused by downward movement of the ground, so for example by damaged drains subsidence cracks are generally more than 3mm and visible on the outside and inside of your home. Diagonal and usually wider at the top.

Answer 73

Heave: The upward movement of the ground beneath a building as a result of the soil expanding. Causes: Tree removal (increase in soil moisture), frost heave, burst sub terrain water pipes. Subsidence: The ground beneath a building sinks, pulling the property’s foundations down with it. Causes: Prolonged dry spells particularly with clay rich soils, trees drawing moisture and collapsed mines. Settlement Downward movement due to compression of soil due to weight of building within 10 years from construction. Causes: occurs after construction.

Answer 74

diagonal cracking along brickwork cracking wider at the top close to weak points in the structure such as windows and doors visible internally and externally

Answer 75

Cohesive soils such as clay. Possible causes include removal of trees, change in water table, leaking drains or inadequate foundations that are built within the movement zones.

Answer 76

Asbestos. Concrete carbonation of the concrete frame. HAC.

Answer 77

Radon is a natural, colourless, odourless, radioactive gas formed by the radioactive decay of uranium that occurs naturally in rock and soil. Exposure to particularly high levels of it may increase risk of developing lung cancer. Some areas of the UK have higher concentrations due to geology and soils e.g Cornwall, Devon and Sommerset. Radon can build up in some underfloor areas and enter a building. A well installed damp proof membrane (radon barrier). Air vents (with fans if needed). Radon sumps. There are others.

Answer 78

Type A: Basement tanking used internally or externally (applied during the construction process). Any defects to the membrane will have damaging consequences and those defects to external tanking systems will be impossible to rectify. Internal tanking systems can be penetrated by fixings and can be displaced by build up of hydrostatic pressure. Type B: Structurally integrated protection whereby waterproofing is provided by walls themselves (reinforced / prestressed concrete). Need to carefully consider jointing details as they can leak. Type C: Drained cavity system whereby water is allowed to pass through the external skin into the cavity and is then pumped away by an electric pump. Can be problematic when there is a high water table and failure of pumping system (usually due to accumulation of fine silts etc).

Answer 79

Subsidence — A movement down in the ground level. In clay soil, the growth of large trees which remove water from the ground can cause this. This leads can lead to vertical cracking if in the centre of the building or diagonal cracking if at the corner of the property. The cracks will be larger at the top and thinner at the bottom. Heave — A movement upwards in the ground level. In clay soil the removal of a tree will lead to an increase in the moisture content of the soil which will cause the soil to swell. This leads to vertical cracking if in the centre of the building or diagonal cracking if at the corner of the property. The cracks will be larger at the bottom and thinner at the top. Settlement — A movement down due to an increased load. Buildings will settle when first constructed or if there is a change in the load as the new load settles to the bearing capacity of the soil. Differential Settlement — If two sections of a building are constructed off different foundations or the ground is made up of different soil types or strata then one may settle more than another causing cracking between the two sections of the building. Most common with extensions. Thermal movement — Either expansion or shrinkage of the masonry, is often characterised by vertical cracks with a relatively constant width if appropriate expansion joints are not present Lintel failure — Lintel failure allows a triangular section of brickwork above the window to drop down creating a triangular crack from the corner of the window toward the centre. Corroded Steel lintel — Where a steel lintel has been used above an opening and the edge is exposed or close to the surface this can corrode over time and expand causing cracking. Cavity wall tie failure — corrosion of large steel fishtail ties will lead to cracking every 4 or 5 courses as the steel expand

Answer 80

Subsidence cracking: Usually diagonal, runs through masonry and blockwork and usually wider at top than bottom. Heave cracking: Usually wider at base and as above. Appoint a structural engineer!

Answer 81

Can pull more moisture of soil, particularly during dry seasons causing subsidence and then once removed can lead to excess moisture and heave of soils. Roots dont usually directly affect buildings, they damaged water and drainage which then cause issues. Oak and Poplar have strong root activity. Safe building distances vary but good rule of thumb is to limit proximity of tree equivalent of that of its full maturity height.

Answer 82

The concern comes from the potential for movement that have given calcium silicate bricks the label of deleterious otherwise the bricks actually increase in strength when exposed to atmospheric carbon dioxide although does shrink it too. In highly polluted areas, sulphur dioxide in damp conditions causes the calcium silicate to decompose to form a gypsum crust.

Answer 83

Defect - Popular in the 1960, and early 1970s, brick slips were seen as an easy method of concealing the exposed edges of a concrete frame at each floor level. A failure to recognise the propensity of a concrete framed building to shrink created circumstances where the brick slips could be stressed and forced off the building, often with serious risks to health and safety. The provision of movement joints above and below the course of slips is essential, but great care is needed to ensure that even the smallest amount of bridging of the soft joint does not occur. Brick panels within either exposed concrete frames or supported on knibs can similarly be affected by unplanned shrinkage in a concrete frame. Remedy — Depends on the severity of the defect but in essence sufficient movement joints are required to take account of the different movements of the different elements.

Answer 84

Used in buildings between 1954 and 1974. Precast pre-stressed concrete beams particularly in maritime buildings. Leaves concrete friable and sometimes browns it. Usually found in roof beams.

Answer 85

Penetrating Rising Condensation ( + interstitial condensation)

Answer 86

Measures the electrical resistance between two electrodes. Generally used for moisture in wood.

Answer 87

Measures moisture in masonry through adding masonry dust into a container with calcium carbide which releases a gas in proportion to the moisture present.

Answer 88

Destructive techniue, Danger of fire/explosion if the regent is exposd to moisture, Generally not as quick as other methods,

Answer 89

A cold bridge is created when poor thermal insulators come into contact allowing heat to flow through the path. E.g. at the junction of a concrete slab and external walls.

Answer 90

Generally occurs in top corners of rooms where warm air rises and collects and due to the change in temperature, the warm air releases vapour onto the colder surface. It is an issue in poorly vented and cold buildings where there is high moisture volume. It can be remedied by venting the property better and maintaining regular internal temperature.

Answer 91

Generally should be left for 3-4 months but this is not practical.

Answer 92

Lateral damp ingress from defected cavity ties. Due to mortar dropping onto the cavity tie which allows moisture to penetrate through the brick. Remedy is to remove the wall tie and replace it.

Answer 93

Penetrating – Enters via a porous bridge transferring moisture through capillary action or there might be a hole in the building fabric. Rising – Moisture rising up from the ground through capillary action normally up to 1m high with tide marks. Usually from bridging of DPC or lack/failure of DPC. Condensation – Warm moist air comes into contact with cold surfaces which releases the moisture. Generally at high level.

Answer 94

Firstly, what is the building made from and what is the construction method? Are there local factors such as trees or high water tables? Have any alterations been carried out? Are there any nearby drains where the cracking is. What is the age of the building

Answer 95

Subsidence – shrinkage of clay Heave – saturated clay Settlement – Movement from increased load. Differential settlement – when parts of a building are constructed off different foundations or the ground has different soils, they move at different speeds. Lintel failure – Usually leads to triangular cracking to the brickwork above the window to drop. Internal alterations – drying of timbers or installation of steel beams without consideration of impact.

Answer 96

BRE Digest 251 Hairline crack - less than 0.1mm wide (cat 0) Fine Crack - Up to 1.0mm (1) Moderate Crack - up to 5mm wide (2) Major crack - from 5mm to 15mm Severe - 5mm - 25mm Very severe - more than 25mm

Answer 97

Crack width gauge, Plastic tell tale, Glass tell tale, Brass screws and callipers, target and total station

Answer 98

Steel ruler is simple instrument used to monitor crack width variation. The crack can be measured to the nearest 0.5mm. Typically used at the start of a crack investigation.

Answer 99

The plate with scales marked in millimeter units of measurement is fixed on one side of the crack and the other plate marked with cursor is fixed on opposite side of the crack. Pros include; They can measure cracks along two axis, can get corner crack monitors. Cons include; fixings can come loose expecially if stuck on with adhesive or if knowcked. Typically 1.0mm degree of accuracy.

Answer 100

This technique used to measure crack width variation in the past, but it is not popular any more. It basically consists of strip of glass cemented on to the cracked structural element. This method is no longer used because there is no way of measuring the extent of the movement or direction.

Answer 101

In this technique of monitoring crack width variation, two screws are fixed on each side of the crack at 90 degrees. The screws will guarantee the correct measurement of the crack width and prevent errors. Digital calipers often have a resoloution of 0.01mm. In some cases discs are glued onto the wall.

Answer 102

Typically used to monitor larger scale movement i.e. bridge subsidance. Recorded from a known datum to ensure co Accuracy up to 1.5 at a distance of up to 1,500 meters. This can also be achived by laser reflective targets fixed to the structure. This is typically more expensive and time consuming.

Answer 103

General rule of thumb is that it is caused by differential settlement due to different foundation types. It could also be because windows were swapped and the new window is not strengthened and causes the bay to drop.

Answer 104

Insect attack Dry rot Wet rot Structural defects

Answer 105

Dry Rot – Wood shrinks and splits into cuboidal cracks. Wood is light in weight and crumbles under fingers. Usually mycelium on the surface which is grey when wet and yellow/purple when dry. Fruiting body usually brown/red in colour. Indoors only. Wet Rot – Wood shrinks and splits. Wood darkens. Mycelium grows on surface which can be white, brown, green or amber in colour. Fruiting bodies can be different colours and occurs internally or externally.

Answer 106

Dry Rot — Wood shrinks and splits into large cuboidal cracking, the wood is light in weight, crumbles under fingers and has a dull brown colour, cotton wool type mycelium is often visible greyish in colour when wet and yellow/purple when dry, strands are brittle when dry, a fruiting body can also occur with a reddish brown colour, only incurs inside of buildings. Wet Rot — Wood shrinks and splits on a smaller scale, wood becomes darkened, mycelium can be white, brown, amber, green or black, strands are flexible when dry, the fruiting bodies can be a number of different colours can occur both inside and outside. Wet rot usually caused by a source of moisture and dry is generally from condensation/humid environments.

Answer 107

Locate and remove the source of moisture and dry out the timber Remove rotten wood plus 450mm Apply fungicidal fluid and strengthen joists if required

Answer 108

50-60% for Wet Rot. Will not survive below 44%. 25% for dry rot

Answer 109

Features include shrunken wood with cuboidal shapes. Cotton wool type mycelium on the surface. Timber crumbles under finger. Fruiting bodies are red/brown in colour and pancake shaped. Identify the rot and where it is at its worst. Remove the cause and strengthen the joists as required or fully replace. If the dry rot has passed through the masonry, this will need sterilisation too.

Answer 110

Spores – with dry rot, it is a fine orange brown dust. The spores activate when in contact with timber. Hyphae – Timber and moisture are present, the spores will produce fine white strands which allows the rot to grow by feeding on timber. Mycelium – Hyphae mass is known as mycelium. It grows on various materials and over vast distances which allows it to progressively destroy the structural timber. Fruiting Body – Mushroom like form pumps spores into the air which is transferred by air currents and germinates it to create a new attack. Repeat the process

Answer 111

Category A (insecticidal treatment) – common furniture beetle, death watch, house longhorn beetle. Category B (treatment of rotten area only) – wood boring weebills. Category C (No treatment required) Bark borers Remedial methods – study flight holes to identify beetles and determine if it is still active or dormant. Apply boron-based treatment to affected areas

Answer 112

Common Furniture Beetle Death watch beetle Wood boring Weevil (Less common in UK) House Longhorn Beetle

Answer 113

Churches/old buildings with hardwood and timber suffering from fungal decay.

Answer 114

Holes in wooden item with frass around the holes. Typically 1-1.5mm holes

Answer 115

Adult beetles lay eggs on the timber. The grubs feed on the timber, hatch into beetles which breed, lay eggs and the process repeats.

Answer 116

Most woodworm requires high moisture. May indicate an issue with the structure and damp.

Answer 117

Chemical insecticides. Resolve damp issue as damp wood may be re-infected

Answer 118

Lays eggs on the surface of the wood Larva grows in wood crevices (Takes 1-5 years) Pupa (Larva to adult) Adult flights/crawls from the timber Stage 2 is when the most damage is done to the timber

Answer 119

Furniture beetles and longhorn – 2-5 years Death-watch beetle – up to 10 years

Answer 120

Confirm why the floor is deflecting. Notching to joists, not adequate for spans? Inadequate support? Can the issue be remedied without destroying the floor? Supplement the joists, overboard or remove it and replace.

Answer 121

I would review any existing building information available before inspecting the property. I would look at the building as a whole to get an understanding of its construction, and the materials used, assess whether there had been any alterations to the building. I would inspect the leak and talk to the building owner/user. I would look at the extent of the leak and the damage caused and ask questions relating to the history of the leak. When did it occur does it happen all of the time or just on occasions is it affected by the whether? I would then assess whether there were any external elements that could be the cause and then any internal elements that could be the cause. My first thought would be a roof leak so I would assess the roof both externally and internally for signs of defective or missing roof covering, defective or missing flashings around roof penetrations etc. Then when in the roof space I would look for evidence of leaking pipes.

Answer 122

Poor or inadequate curing – environmental conditions being conducive to evaporation and lack of protection. If the mixture is too wet or excessive floating which causes aggregate to sink, the cement paste on top will start to crack.

Answer 123

Occurs in glass production. Microscopic imperfections in the glass. When the glass is tempered, the nickel sulphide inclusions do not return to the normal low-temp state for several years and expands in the process which can cause cracks with no obvious cause.

Answer 124

Structural movement above/below causing the frame to move or distort.

Answer 125

Soil shrinkage Tree Roots Water Table Leaking draings/below ground services Infill site/brownfield sites/mines Nearby Excavations Subsidence

Answer 126

Horizontal cracking every 5 or so brick courses. Corrosion of old steel ties causes the cracks. Remedy – use a borescope to determine the defect. Locate the wall ties and isolate and remove. Install replacement stainless steel mechanically fixed ties.

Answer 127

Common with slates or tiles. Nails have rusted and expanded which cracks the tile allowing them to slip. Generally, if one nail has failed, several are likely to fail too.

Answer 128

Plastisol degradation Cut edge corrosion Defective fastenings

Answer 129

When cut edge of coated metal are exposed to elements, delamination may occur in the form of peel back of factory coating. The unprotected metal then rusts and corrodes. Can be remedied by applying a silicone paint. If the corrosion is bad, may be better to replace the panel.

Answer 130

Plastisol is a PVC coating. Usually has a leather effect. Or use PVF2 which is a thinner material with a smooth finish. These are both effected by temperature, UV exposure which can lead to caulking and delamination.

Answer 131

Asbestos Concrete defects Cold roof Wood wool slabs

Answer 132

Cut edge corrosion Plastisol degradation Asbestos use in insulation

Answer 133

Carbonation occurs due to the ingress of atmospheric carbon dioxide reacting with water within the concrete, which forms carbonic acid that neutralises concrete alkalinity This breaks down the passive layer around the reinforcement causing it to corrode due to the presence of water and oxygen. This happens at a slow rate (progressive) Carbonation is more of a concern where there is poor or shallow cover over the steel reinforcement, or the concrete is poorly compacted Carbonation is more rapid in porous concrete with low cement content and concrete with high water to cement ratio

Answer 134

Occurs to reinforced concrete buildings and structures – it is inevitable Fine cracks appear in the concrete causing the reinforcement to corrode Hairline cracks appear along the reinforcement line The reinforcement expands due to the rusting Concrete spalls and cracks exposing the reinforcement

Answer 135

Apply a solution to the concrete that can highlight any areas of carbonation in the concrete

Answer 136

Replacement – this involves removing defective concrete and cutting out the reinforcement to damaged members. New reinforcement is fixed but welding to existing and new concrete is cast. This is the simplest method and completed by specialist contractors. Gunting – a propriety process in which fine concrete is sprayed onto a concrete surface under repair of high velocity. Coating – coatings, sealants and membranes can be effective in reducing the carbonation process. however, if chloride is present at rebar depth then the coating will not prevent carbonation. Electrochemical re-alkalisation – the cathodic reaction around rebars produce hydroxyl ions. The steel cathodes also attack alkali metal ions towards its surface, so high alkalinity is restored around rebar. A temporary anode (steel mesh) is attached to concrete, the electrolyte penetrates the concrete and raises the alkalinity at the cover. An anti-carbonation coating is applied. Cathodic protection – this is a permanent and very expensive technique. an anode system (coating or mesh) are sprayed or fixed to the whole surface of concrete. A current is applied which passes to the reinforcement, which is then made cathode preventing corrosion of the reinforcement.

Answer 137

High Alumina Cement was used in the production of pre-cast concrete sections. This has very high strength at an early stage, however, loses strength as it ages and is susceptible to chemical attack in damp conditions. Introduced in 1925, cement producer Lafarge commenced the UK manufacture of High Alumina Cement to provide concrete that would resist chemical attack, particularly for marine applications. Used in the UK from 1950-1976 in the manufacture of pre-stressed concrete beams

Answer 138

HAC concrete undergoes a mineralogical change known as conversion. During this process the concrete increases in porosity which in turn results in a loss of strength and reduction in resistance to chemical attack. The higher the temperature during the casting of the concrete the more quickly conversion takes place.

Answer 139

An investigation should be undertaken consisting: Sample testing Collect details of construction materials used – the local authorities hold records of HAC buildings If the strength has been reduced – reduce the live loads or strengthen In the case of reinforcement corrosion – localised repairs can slow further deterioration

Answer 140

Occurs where the chemical within the cement react with silica (in aggregates), forms a gel substance which absorbs water and expands creating cracks where water can enter. Further cracking may occur as a result of water freezing within the cracks. * Cracking * Small pop outs * Map cracking * Tensile strength reduced * Gel absorbs water causing further cracking * Cracks run parallel to reinforcement bars

Answer 141

Remove one of the following and ASR will not take place: Critical silica in aggregate Sufficient moisture High alkalinity Use low alkali cement and avoid use of chemically reactive aggregates Consider complete replacement of an ASR affected section to maintain integrity and safety

Answer 142

Chlorides may either ingress (from penetration of de-icing salts) or cast insitu as sea dredged aggregates or calcium chloride additive. Chloride ions attack the reinforcement can cause: In certain circumstances ‘pitting’ corrosion can occur – when the steel is effectively eaten away without the formation of expansive rust Corrosion of steel reinforcement is localised compared to carbonation and much more rapid. Spalling of concrete Significant loss of cross-sectional area Pit in bar surface – rebars could be completely eaten away Visual sign of cracking and spalling following expansive rusting

Answer 143

Cathodic protection Corrosion inhibitors Epoxy resin repairs

Answer 144

The downward movement of the site/ground where a building stands Can also be associated with Heave

Answer 145

Identified by diagonal cracking which is usually tapered (of uneven width) in the buildings structure/façade and verified by leaning or pulling of the building. Subsidence usually shows up as cracks that are typically wider at the top than the bottom. They commonly appear around windows, doors and other weaker areas. Doors and windows may stick when opening them, walls and floors may show signs of distortion.

Answer 146

Tree extracting water shrinkable clay ground mining activity

Answer 147

Refer to BRE guidance to understand how to assess damage. Remedying the source of the problem can be effective, however it can sometimes make things worse i.e. removing a tree causes moisture to return = heave Underpinning is an option but it is expensive and disruptive Use pneumatic jacks to lift the building and reverse the movement

Answer 148

Concrete does not adequately get compacted. Risk of poor cover to the steel and hence loss of durability, possible reduction in strength, and loss of fire resistance. Voiding and honey combing due to vibrations. Poor bond or failed bond between the wood wool and the hardened concrete. Buildings constructed from 1950 to the mid-1970s are most likely to be affected by this form of construction. If permanent shuttering is discovered, intrusive investigations may be needed to determine the adequacy of concrete cover to the steel reinforcement. If voiding is present, the affected area can be exposed and repaired using hand-fixed concrete repair methods or, if over a larger area, sprayed concrete.

Answer 149

Cut edge corrosion. Delaminating plastisol finishes. Missing caps to fixings. Leaking gutter joints. UV damaged roof lights. Cracking – subsidence, heave, settlement etc. Impact damaged cladding. Asbestos. Carbonation. Cracked floor slabs.

Answer 150

Loss of transparency, embrittlement etc caused by ultraviolet light breaking down polymers in the rooflight plastic. Incorrect installation: 2 lines of sealant should be installed to each end of a rooflight (usually recommended by manufacturer’s). Embrittlement of foam fillers by UV degradation.

Answer 151

Loss of colour Caulking Delamination

Answer 152

Reinforced bitumen membranes: Constructed by bonding 2 or more layers of reinforced bitumen with hot bitumen (can also get single layer RBM systems too). Polymetric single-ply: PVC. Laid and can be fully fastened, fully adhered, or loose laid and ballasted. Mastic asphalt: Graded limestone aggregate bound together with an asphaltic cement (bitumen). Heated to 210 degrees and applied with a wooden float. Liquid roof systems: Monolithic, fully bonded, liquid-based coating with a rubberised finish. Profiled sheets. Lead, zinc, copper and steel sheet.

Answer 153

Tapered insulation or roof deck not laid to correct falls (timber firrings used to set roof deck falls). Deflection of timber roof deck - through reduction in structural integrity of structural timbers - rot / insect infestation. Blocked rainwater goods. Subsidence / heave.

Answer 154

Visual Electronic leak detection Thermographic examination

Answer 155

Its age and life expectancy, the overall condition i.e. are the defects localised or affecting the whole of the roof, what type of defect is it and does it relate to a localised factor or is it an issue with the whole roof, are they affecting the surface layer or the roof structure. Client’s intentions for the building, their budget, the building use, disruption caused and possible phasing required? * Age * Condition * Extent of Defect * Cost * Use * Life Cycle Costing * Disruption associated with repair and replacement.

Answer 156

Firstly gather historical building information and details of any current or previous issues with the roof. Make arrangements for access and prepare necessary RAMS. Firstly identify: * Age * Previous repairs * Period defective for * When does it leak * Does water pond * Use of room below * Used as a balcony or terrace * Access arrangements Secondly carry out a visual inspection during or after rain

Answer 157

Mould growth Any stains or streaks of water dampness behind furniture/inside wardrobes etc.

Answer 158

Where condensation is formed within the fabric of a building

Answer 159

Issues: Can cause dampening of insulation materials which can lead to reduction in performance and eventual physical deterioration. If forming against timbers, can promote rot and insect attack. Rectification: Changing of the building detail if there is an inherent defect. Replacement of insulation if penetrated such as in a cold roof build up - insulation penetrated by fixings, vapour then passes through vapour control barrier and then into the very cold roof void allowing condensation to form on structural timbers.

Answer 160

Most are calibrated for timber and can’t give accurate readings for other materials. Measures can be affected if timber has been treated with waterbased preservatives and the temperature of the wood can also effect readings.

Answer 161

Crazing - Surface crazing caused by lack of protection from UV exposure. No treatment is required if in small localised patches but should be monitored. Ponding - If the gradient is not sufficient and there are dips in the roof finish, it can lead to pools of water. It can lead to water ingress if there is a gap in the roof finish. Thermal Movement Cracks and splits can occur when there is thermal movement between the substrate and membrane. Usually requires localised repair to the area around the crack. Blistering - Caused when water vapour beneath the roof finish increases. The source of moisture should be traced and the blister opened and allowed to dry before patch repairing. Flashing and Falls around openings- Defective lead from deterioration or poor workmanship around openings causing water ingress. Depending on the issue with the lead, there are different repairs. People - Punctures caused by people from impact damage. Cracks and tears along the line of joists - Caused by thermal movement or saturation of insulation or sagging decking. Repaired by cutting felt back and allowing it to dry before patching over.

Answer 162

Passivity is generated by the buildup of a layer of metal oxide on the surface of a metal. In order to provide passivity, this oxide layer must be stable. It is formed by corrosion insoluble components in the immediate environment of the metal. The metal oxide acts as a barrier by separating the metal’s surface from its environment and prevents corrosion until the reactants are able to diffuse through the oxide film. This diffusion may take a significant time to occur.

Answer 163

A possible cause is the lack of lateral restraint in the wall. If the floor joists are running from the front to the back of the house then there may be nothing connecting the flank wall to the building at the first and second floor levels. This may be due to poor design or some alteration in the internal layout such as a change in position of the staircase. Other potential causes to consider include cavity wall tie failure or increased roof load.

Answer 164

Heave — Usually in cohesive soils such as clay. Possible causes include removal of trees, change in water table, leaking drains or inadequate foundations that are built within the movement zone. Subsidence - In all soil types. Differences in the type of soil leading to differences in the bearing capacity, a change in the water course or high water course, defective drain, voids in ground collapsing. Growth of trees removing water from the soil.

Answer 165

Elm, Oak, Poplar, Willow trees

Answer 166

how much water trees take in/require from the ground which can affect soil and cause subsidence, and potential heave when a tree is removed.

Answer 167

Missing or broken handles Windows that don't close (faulty hinges) Rotten sills glass fogging in double glazing (broken/aged seals allowing moisture into the pane) broken glass

Answer 168

Causes of cracking in buildings and the results of the problems. Broad understanding of crack diagnosis and repair.

Answer 169

Physical Changes (i.e. efflorescence, temp changes, shrinkage) Chemical Changes (i.e Sulfate attack, carbonation, alkali silica reaction) Imposed Load Effects (structural loading) Differential Soil Movements (settlemen, mining, land slips) Vibration (traffic, machinery, mining, explosions)

Answer 170

This Digest discusses the assessment and classification of visible damage resulting from structural distortion. The assessment is based on a description of work considered necessary to repair the building fabric; classification into six categories is recommended, taking into account the nature, location and type of damage.

Answer 171

This can be done by questioning the occupants on the date of discovery and by examining the fracture surfaces, particularly of external cracks, for signs of age. For instance, recent cracks in brickwork have a clean appearance, whereas older cracks show signs of dirt accumulation.

Answer 172

3 Broad categories ‘Aesthetic’, ‘Serviceability’ and ‘Stability’. and category from 0 - 5. (0-2 is aesthetic) 3&4 (serviceability) and 5 (stability). 0 Hairline cracks of less than about 0.1 mm which are classed as negligible. No action required. 1 Fine cracks which can be treated easily using normal decoration. Damage generally restricted to internal wall finishes; cracks rarely visible in external brickwork. Typical crack widths up to 1 mm. 2 Cracks easily filled. Recurrent cracks can be masked by suitable linings. Cracks not necessarily visible externally; some external repointing may be required to ensure weather-tightness. Doors and windows may stick slightly and require easing and adjusting. Typical crack widths up to 5 mm. 3 Cracks which require some opening up and can be patched by a mason. Repointing of external brickwork and possibly a small amount of brickwork to be replaced. Doors and windows sticking. Service pipes may fracture. Weather-tightness often impaired. Typical crack widths are 5 to 15 mm, or several of, say, 3 mm. 4 Extensive damage which requires breaking-out and replacing sections of walls, especially over doors and windows. Windows and door frames distorted, floor sloping noticeably. Walls leaning or bulging noticeably, some loss of bearing in beams. Service pipes disrupted. Typical crack widths are 15 to 25 mm, but also depends on number of cracks. 5 Structural damage which requires a major repair job, involving partial or complete rebuilding. Beams lose bearing, walls lean badly and require shoring. Windows broken with distortion. Danger of instability. Typical crack widths are greater than 25 mm, but depends on number of cracks.

Answer 173

material shrinkage and creep; corrosion or decay; differential thermal movements in dissimilar materials; poor detail design or workmanship.

Answer 174

- ground subsidence and heave due to volume changes in clay soils; - settlement and heave of floor slabs on unsuitable or poorly-compacted in-fill beneath the slab; - instability of sloping ground; - movement due to consolidation of poor ground or made-ground; - mining subsidence; - movement caused by nearby excavations; - chemical attack on foundation concrete or erosion of fine soil particles due to the passage of water, for example from a leaking pipe. Also included is differential settlement induced by unequal foundation pressures arising from such factors as extensions added to existing buildings or concentrations of load, for example under chimneys.

Answer 175

Mine Fungus (also known as fibrovaillantii). A form of wet rot often mistaken as dry rot. The fungus grows on coniferous trees such as pine. The fruiting body is an irregular white plate with a thickness of 2-12mm. White cotten like mycelium can grow, in newly formed mycelium fine drops of clear liquid maybe present.

Answer 176

What is Ground heaveGround heave is the upward movement of the ground usually associated with the expansion of clay soils which swell when wet.

Answer 177

Change in the level of the water table. Broken drains or nearby building works that interfere with existing ground drainage. Swelling of the sub-soils due to seasonal weather changes. Freezing of silty and sandy clays can be more susceptible. Soil being removed from an excavation and so relieving pressure on layers below.

Answer 178

Vertical cracking to brickwork and windows. Doors sticking as their frames become out of square. Lifting of paths and patios surrounding buildings.

Answer 179

Cellular structures such as a cellular raft foundation may be installed beneath foundations and floor slabs to reduce the upward force of heave from transmitting to the structure above. Underpinning may be necessary to stabilise structures. Excavated soil from beneath existing foundations is replaced with material, usually concrete. Remedial works such as repairing leaking drains or removing vegetation may resolve the problem.

Answer 180

The Health and Safety Executive (HSE) has compiled recommendations for employers about how to investigate the possible causes of sick building syndrome; Look for the obvious Check the symptoms Ask the staff what the problems are Check procedures and working practices

Answer 181

Since awareness of SBS developed in the 1970s, researchers have tried to pinpoint the precise causes, however, no one single cause has been identified. The most common risk factors believed to contribute to SBS include: Inadequate ventilation. Low humidity, Fluctuations in room temperature. Inadequate sound insulation High levels of noise created by piping M&E Airborne particles such as dust Airborne chemical pollutants

Answer 182

Oversailing of DPC Buckling or bowing of walls Fracture of the masonry units Fracture of an outer cavity wall with no joints

Answer 183

Approved document C requires that, to prevent rising damp, a damp-proof course should be: Continuous with any damp-proof membrane in the floor. At least 150 mm above the level of the adjoining ground if it is in an external wall. If it is in an external cavity wall, the cavity should extend at least 225 mm below the damp-proof course, or a cavity tray should be provided with weep holes every 900 mm so that water running down the cavity cannot pass to the inner leaf.

Answer 184

DPC across the cavity instead of a cavity tray Missing DPC at corners where the cavity trays meet Not vertical protection where cavity trays step down Raised ground level above DPC Rendered over the DPC

Answer 185

Slate Membrane Engineering brick

Answer 186

Elizibeithan / Tudor 1500s Exposed timber frame infilled with wattle and daub, painted in it’s iconic black and white colours Only brick was typically used in the chimneys Glazed windows widely used. Glass is small and imperfect. 2nd floor typically overhangs the first Roofs typically relatively steep

Answer 187

Condensation Penetrating dampness Rising dampness Leaks (e.g. from pipework) Trapped construction water (new builds)

Answer 188

Health hazard Reduce strength of building materials Cause movement in building elements Lead to timber decay (dry and wet rot, insect attack) Cause chemical reactions in building components Reduce effectiveness of insulation Damage decorations

Answer 189

A sample is weighed, dried in an oven and then weighed again Moisture content = (wet weight - dry weight x 100) / dry weight

Answer 190

Dew point - the temperature at which the air becomes saturated and will condense

Answer 191

Relative humidity - moisture content present within the air, referred to as a percentage of the amount of water vapour it can hold at that temperature

Answer 192

Wall has a ‘misty’ surface Stains or streaks of water running down a wall (particularly in bathrooms, kitchens and below windows) Damp patches with no definitive edges Dampness behind wall cupboards or inside wardrobes against external walls (areas where air circulation is restricted) Localised dampness at potential ‘cold bridges’ Patches of mould growth Humidity (measured using a hygrometer), insulation and ventilation levels, as well as heating and living patterns, must also be taken into account

Answer 193

Reduce moisture generation (lids on pans, dry clothes outside, vent tumble dryers externally, do not use paraffin or bottled gas heaters, put cold water in bath before hot) Increase ventilation to remove moisture-laden air (open trickle vents, open windows, mechanical ventilation) Increase air temperature by heating - warmer air can hold more water vapour without condensing Increase surface temperature by thermal insulation (external or internal)