Building Pathology Flashcards
1
Q
For the Walthamstow project when did you undertake an inspection of the roof space to paste the tissue?
A
Prior to Spring, Death Watch Beetles emerge in Spring to lay their eggs
2
Q
For Walthamstow why does the woodworm infestation occur?
What is the lifecycle of a woodworm insect?
A
Invasive and survives using the woods nutrients, enjoys soft and damp timber.
Cycle of eggs, larvae, pupa and adult. Lay eggs in spring months. Growth can take up to 10 years, live a few months as an adult.
3
Q
During your Westcliff project you said that areas of concrete had deteriorated due to carbonation, what made you know it was carbonation?
A
Concrete hammer test confirmed hollow areas, degraded concrete, phenolphthalein test colourless instead of pink showing carbonation, steel starting to corrode with rust apparent.
4
Q
How would you repair carbonated concrete and corroded steel? what is the coating applied?
A
Break out concrete, clean reinforced bar and apply anti corrosion coat, repair concrete and apply anti carbonation coating to shelf angle. Priced for repairs up to 50mm in depth.
Resin based anti carbonation coating applied.
5
Q
What reacts in the concrete with the carbon? How does carbonation affect the steel?
A
Carbonation converts the calcium hydroxide in the cement to calcium carbonate causing degraded concrete, the pH alkalinity to drop and steel to react by breaking down its barrier causing corrosion.
6
Q
How do you generally ensure high strength and good quality concrete?
A
Vibrating and trowelling concrete and cube testing during construction. Allow to cure for required amount of time and QA checks.
7
Q
What are the main features of Georgian / Victorian / Edwardian / 1960s era?
A
Georgian 1714-1830 - spacious with grand proportions, bricked up windows, three or four storey townhouses, sash windows, stucco fronted exterior, built around garden squares.
Victorian 1837-1901 - terraced housing, high ceilings, large windows, cramped, wood floor, high pitched slate roof, coloured brickwork, brick porch, narrow hall, bay windows, fire place, patterned wallpaper.
Edwardian 1901-1910 - Simple design, garden suburbs, roomy, bigger hallways, more windows, ornate details, red brickwork, mock tudor cladding, parquet wood floors, simple decorative features.
1950s/60s - weatherboarding cladding, boxy, low pitched roof, concrete roof tiles, fitted kitchens, open plan, vinyl floor.
8
Q
What are the defects found in Georgian / Victorian / Edwardian / 1960s era buildings?
A
- Georgian - No DPC, snapped headers, poor restraint (no wall ties) so bulging walls, stone defects and sulphur attack, damp penetration through thin walls, timber lintel decay, stucco render cracking and water ingress, shallow foundations, lime plaster replaced with modern gypsum or cement which isn’t breathable, lead paint, asbestos, anthrax.
- Victorian / Edwardian - Sulphate attack to chimney, chimney support / breast removed, slipped or cracked slates, overloading of structure with concrete tiles, rainwater goods failure (corroded or blocked), no DPC, snapped headers, poor restraint (no wall ties) so bulging walls, removal of structural partitions, timber lintel decay, floor joist over notching, blocked air bricks / poor ventilation of sub floors, timber decay, built in timbers prone to decay, lead paint, asbestos and anthrax.
- 1960s - Wood wool and permanent shuttering, HAC, asbestos, cut edge corrosion, concrete chemical attack (carbonation), boot lintels (rotate forward due to load), brick slips to concrete frames and thermal movement, calcium silicate brickwork, mosaic tiles loss of adhesion, calcium chloride additive increases corrosion, Glass Reinforced Cladding (loss of strength), lack of movement joints, made up ground, removal of soil due to RWGs, asbestos, calcium chloride, nickel sulphate reaction.
9
Q
For the Colchester gym building, why are movement joints installed?
A
Allows for expansion and contraction of the materials (heating causes this) and prevents cracking and damage
10
Q
For the Colchester gym building, at what distances should movement joints be installed?
A
clay brickwork requires a movement joint every 10m and at least 550mm from end of wall.
11
Q
For the Colchester gym building, how did you know the cracks were due to the expansion joints and not due to something structurally more serious?
A
- Cracks were vertical and along where the expansion joints should have been installed.
- There were no expansion joints even though wall was more than the 10-12m recommended.
- I inspected the building and could not determine any other structural issues, e.g. heave which would have had a different nature of crack.
12
Q
For the Colchester gym building, why did you replace the bricks and not just undertake a repair?
A
- Bricks were fairly significantly cracked, more than hairline
- Replacement would ensure no structural issues
- Deemed marginally more expensive but worth replacing the bricks
13
Q
For the External decorations project, what were the different door options?
A
- Repair
- Install hardwood timber door
- Aluminium door
- Steel door
- Fibreglass door
- Glass door
14
Q
For the external decorations project, why did you recommend the aluminium door replacement?
A
- Secure
- Durable
- Recyclable
- Good thermal properties
- Cost effective in long term
- Resistant to weathering
15
Q
For the Walthamstow project, what size emergence holes would you expect to see?
A
honeycomb appearance and 3mm diameter holes.
16
Q
In regards to the Walthamstow project, how do you prevent reoccurrence of an infestation?
A
- Specialist engaged to terminate woodworm
- Apply incesticide to timbers
- Repair timber as necessary and engage structural engineer if necessary
- Improve ventilation to ensure completely dry timbers. Install eaves ventilation or roof tile ventilation.
17
Q
What are other woodworm infestations? How did you know it was the Death Watch beetle
A
Common furniture beetle, house longhorn beetle and wood boring weevils.
Death watch beetle is medium sized and brown with hairs, they form 3-4mm holes and tapping can be heard in the night.
18
Q
What type and location of crack would indicate heave?
A
Heave cracking is more likely to be vertical, whereas subsidence is likely to be diagonal.
Heave cracking likely to be wider at the bottom and thinner at the top
19
Q
What are the limitations of a damp meter
A
- Damp meters are misused, defects are not rectified.
- Conductivity issues with metal studwork.
- May require recalibrating.
- If not reading wood will need a WME reading.
20
Q
What are the characteristics of dry rot?
A
- Brittle and cuboidal cracking
- Lower moisture content of 20-40%
- Extensive and can spread to masonry
21
Q
What characteristics determine infestation of death watch beetle?
A
- Medium sized brown beetles
- Tapping in wood at night
- Flight holes 3-4mm wide
22
Q
How often should expansion joints be installed? How may this vary depending on materials?
A
Clay brickwork - 10-12m
Lightweight concrete block - 6m
Parapet wall masonry - half the above spacings and 1.5m from corners
23
Q
Why are would a DPC under the coping stones prevent water ingress?
A
DPC prevents downward transfer of moisture into the wall.
24
Q
As well as a hammer test, what else could determine carbonation?
A
- Observation
- Phenolphthalein test pink to colourless a sign of carbonation
25
What was your advice to the client to resolve death watch beetle infestation?
Exterminate the infestation with specialist to apply insecticide and inject.
Timber repairs or replacement may be required.
Since timbers were around 20% and at a level which was okay but slightly high, improve ventilation with fascia ventilators rather than roof tile ventilators which are installed by puncturing the roof membrane or air purification unit.
Fascia ventilators both sides for cross ventilation, refix fascia board 15mm below, nail to top of fascia board, refix gutter and gutter bracket spacer, relay underlay and roof tiles.
26
What would be the prognosis if the death watch beetle was left?
Continue to multiply and damage the timbers and eventually lead to structural damage.
27
Why did you recommend replacing the brickwork for the gym building? Could repair have been implemented?
Replacing the brickwork was recommended because they were cracks in excess of 2mm. It was not a huge amount of bricks and therefore the cost difference between repair and replace was not huge.
28
How were you able to determine that manufacturing issues had caused the water ingress?
I measured sample windows which were removed and found that the window measurements were not correct and did not fit the window openings. This combined with installation issues had caused the problems.
29
Were measurements undertaken during replacement of the windows because within the report you then stated for all windows to be replaced?
Measurements were undertaken of sample windows replaced at different plots and thereafter once a representative sample was obtained it was specified for all windows to be replaced.
30
How can you differentiate between wet rot and dry rot?
- Undertaking moisture meter readings
- Feeling whether its soft and spongey
- Observation as to the area it has affected
31
How do you differentiate between penetrating damp, rising damp and condensation?
Condensation – black mould spots on walls, damp smell, water collecting on windows, lack of ventilation.
Penetrating damp – bigger after rain, staining patches, black mould, grow in size.
Rising damp – tide marks, 1 metre, yellow / brown colour, salts present.
32
How does rot occur? How can it be eliminated?
- It is caused by a fungus that is attracted to wood and feeds off the timber, destroying it in the process.
- Stop water source, treat timber with fungicide and repair, improve ventilation.
33
Identify the main causes of movement cracks? What do different cracks look like?
Subsidence - run diagonally and are wider at the top of the crack.
Heave - likely to be vertical or diagonal cracks and wider at the bottom.
Settlement cracks - vary in width and direction.
Differential settlement - cracks occur along line of differential settlement.
Insufficient expansion joints - occurs vertically and can be where joint should have been installed.
34
What different factors can cause subsidence and heave?
- Pipe leak or rectification
- Water table rise or fall
- Tree planting or removal
- Ground movement
35
Identify equipment you may require for a survey?
Torch
Camera
Spirit level
Notepad
Phone
Disto
Tape Measurer
Tape Gauge
Damp meter
36
Identify the main types of building survey and the practise statement that sets these out?
Level 1 survey - condition survey
Level 2 survey - homebuyers survey (possibly w/ valuation)
Level 3 survey - full technical building survey
Home Survey Standard 1st Ed 2019
37
Why does metal studwork cause electrode interference? In what other situations does it have limitations?
Conductivity of studwork may affect readings between the prongs.
Limitations in rising damp, if defect is not identified and if not recalibrated correctly.
38
What factors have affected building appearance?
- Material availability
- Technological advancements
- Preferences or zeitgeist
- Cost competitiveness
- Legislation
39
Why do you return in Spring to check the tissue for the Walthamstow project? What is the lifecycle for the death watch beetle?
eggs, larva, pupa, and adult. In Spring they emerge and lay their eggs and this is when they will leave flight holes.
40
What was the cause of water ingress to the gym ceiling?
DPC not installed underneath the coping stones meaning that water was able to penetrate down the cavity, access the building envelope and cause staining.
41
For the Colchester gym building, why does a parapet require a DPC?
To prevent water penetrating through and down the cavity wall.
42
For the Colchester gym building, please describe what you exactly specified for the coping stones?
Coping stones to be removed, Hyload DPC bedded on masonry cement and project 5mm beyond each face of the wall below. A DPC support should be installed.
43
For the Colchester survey, what else would you generally find to the external wall which should be installed?
Cavity tray and cavity closers. Cavity barrier not required as single storey.
44
What are the purpose of expansion joints? What are they formed of?
It allows the materials to expand and contract as/when the temperature changes. It forms a break between the material and other parts of a structure to allow movement without causing stress, which can lead to cracking.
Polyethylene joint backer rod and flexible mastic joint
45
What was the appearance of the cracking to the gym building? What did you exactly specify to prevent reoccurrence?
Cracks occurred vertically and more significant cracks were around locations where expansion joints should have been installed.
Specified saw cut the crack which was over 550mm from end of wall and install backing cord and flexible mastic joint 10mm wide and 50mm deep.
46
What are concrete shelf angles?
A shelf angle or masonry support is a steel angle which supports the weight of brick or stone veneer and transfers that weight onto the main structure of the building.
47
How did you categorically determine that carbonation had caused the deterioration of the concrete?
Phenolphthalein test. Colourless indicates carbonation.
48
For the Westward Ho project, talk me through the process of carbonation with the concrete and steel?
Calcium hydroxide becomes calcium carbonate due to carbon in the atmosphere. This lowers the pH and the concrete degrades. This then affects the protective layer to the steel which starts to become exposed and corrode.
49
What is a concrete hammer test? How did you record which areas had been affected by carbonation?
Rebound hammer and noise and vibration determines whether the shelf angle has been affected by carbonation or is still in sound condition. I marked up an elevation drawing accordingly.
50
For Westward Ho, what did you specify to prevent reoccurrence of the carbonation?
- Anti corrosion coating applied to the steel after preparing and cleaning the steel.
- Anti carbonation coating applied to the shelf angle after concrete repairs had taken place.
51
For the Walthamstow almshouse, what works would need to be undertaken once it is determined that there is an infestation?
- Fascia ventilators both sides for cross ventilation. Refix fascia board 15mm below, nail to top of fascia board, refix gutter and gutter bracket spacer, relay underlay and roof tiles.
- Tile ventilators puncture membrane and aesthetics.
- Air purifier unit.
52
What measures can improve loft ventilation for the almshouse in Walthamstow? How would this help to prevent reoccurrence? What would you have to potentially consider if you are carrying out these works?
Roof tile ventilators, fascia ventilators, air purification unit.
Damp conditions required for establishment but infestation can continue in dry timbers. 20% moisture readings acceptable but little high.
53
At what lengths were the movement joints installed? How many joints were installed to the building and how did you do this?
Every 10m in accordance with NHBC standards. 2 no. expansion joints were installed to the rear where the cracking was observed, this occurred by diamond saw cutting the existing cracks and installing a backing rod and mastic expansion joint.
54
For the Colchester gym building, what is the purpose of a coping stone?
A coping stone is a flat stone used to crown free-standing walls and is a component of a coping. Coping stones are crucial in keeping rain from seeping through the wall.
55
What are backing rods?
Flexible lengths of foam that are used as a “backing” in joints or cracks to help control the amount of sealant/caulking used and create a back stop.
56
In regards to Charing, how did you determine that the water ingress and draughts were most likely due to the windows?
Draughts and staining around windows indicated it was likely to be either the window fitting or an associated defect such as brickwork installation. Inspections confirmed there were multiple defects with the window fittings.
57
For Charing, what methods did you use to determine the windows were poorly manufactured and installed? What equipment did you use?
- Observation and photos of windows.
- Tape measure whilst windows were removed.
- Spirit level to determine if square.
- Noted condition of cavity, mastic, etc.
58
In regards to Charing, how did you measure the windows? Were any windows removed?
Sample windows removed and replaced. Inspected before, during and after. Took photographs, measurements and spirit level.
59
For the Charing project, describe the different issues with the windows. How did these issues lead to draughts and water ingress?
dimensional variations in manufacturing, windows not fitted plumb, no backing rod and sealant between frame and wall, cills not bedded on sealant, cill drip not extending beyond brick face when 40mm overhang is required.
Gaps around windows, mastic not fit for purpose, cills insufficient allowing water to run down brickwork, all caused water penetration and draughts.
60
For the Charing project, what evidence was there of water ingress?
The residents were complaining of draughts and water ingress and the client's surveyor had previously inspected. I inspected and there was staining to the decorations around some of the windows and moisture meter readings confirmed wet areas around the windows.
61
For Charing, how did you know there were dimensional variations? Were the windows in situ?
I measured the windows before replacement and whilst sample windows were being replaced and used a spirit level.
62
What is the purpose of coping stones?
Protect the top of the wall.
63
What are defined as cosmetic and severe cracks?
NHBC define cosmetic as under 2mm and severe as 15mm+
64
Is dampness always bad?
Sometimes buildings are designed to absorb and release moisture. For example lime plasters are damp because they are porous and absorb and regulate moisture.
65
For the Charing project, did you refer to any guidance or BS?
- Dwgs for the project
- Manufacturer's guidance
- BS8213 - Installation of windows and doors.
- BS8000-0 - Workmanship on construction sites.
66
Provide examples of some defects that you may come across when inspecting a building in your ordinary locality?
- Rot
- Woodworm
- Condensation and damp
- Ventilation issues, e.g. - blocked air vents
- Structural issues, e.g. - sleeper walls
- RWG problems
- Deleterious materials
- Asbestos
- Carbonation / alkali silica reaction / calcium chloride / calcium silicate
- Fire safety and fire stopping defects
67
What are some common defects you may come across as a building surveyor?
Modern defects - Cut edge corrosion, flat roof issues, poor insulation, pitting due to atmospheric pollution, curtain walling / rainscreen cladding detachment, symphonic drainage systems, rotation of short returns (insufficient restraint), lack of expansion joints, composite panels fire risk, urea formaldehyde insulation, nickel sulphide inclusion in glass, asbestos up to 1999 and wood wool slabs.
Pre 1900 building defects - Bridged failed or lack of DPC, poor ventilation to floor voids, leaking RWGs, poorly fitted sash windows, modern concrete roof tiles, lack of restraint to walls, hard mortar causing spalling, binding doors and windows, failure of brick or timber lintels, lead paint and water mains, removal of load bearing internal partitions, differential settlement of bay windows due to insufficient foundations, insect attack
68
Identify some issues with the windows at Charing?
Dimensional variations in manufacturing, spirit level windows were not fitted plumb, no backing rod and sealant between frame and wall, cills not bedded on sealant, cill drip not extending beyond brick face. Overhang minimum 40mm recommended.
69
Name the lifecycle of rot. Name the lifecycle of woodworm.
- Rot: a spore, a hyphae, a larger mass known as mycelium and finally a fruiting body that produces more spores.
- eggs, larva, pupa, and adult.
70
What are deleterious materials? What are hazardous materials? Please give some examples of both.
- Hazardous materials are substances that pose a risk to the building and human health, e.g lead (inhaling lead dust), cement (skin issues), UFFI (possibly carcinogenic and irritation), asbestos (lung diseases).
- Deleterious materials were used in good faith at the time but has proven to be a risk to the building over time, e.g. - calcium silicate brickwork (shrinks), calcium chloride additive (corrosion), HAC (reduces strength in high humidity), sea dredged materials (react and corrosion), mundic blocks (loss of integrity in damp conditions), woodwool slab (lack of compaction)
71
What is the difference between hazardous and deleterious materials?
Hazardous - Dangerous to health
Deleterious - Dangerous to the building
72
What RICS guidance do you refer to when investigating moisture? What does it state?
- Investigation of Water and its Effects on Traditional Buildings: Principles and Competencies Position Statement 2022
- Agreed set of principles and competencies that should be used anytime there is a need for an assessment of moisture within a traditional building.
- The surveyor should take a ‘whole building’ approach, look for the source of any excessive moisture, not rely on potentially misleading data and should then provide the client with advice to manage the situation. The document goes into detail in a step-by-step format of what the surveyor should do and ultimately to take responsibility for the advice given.
73
What is the issue with spray foam insulation and what recent RICS guidance is there?
- It converts a cold roof, which was originally designed to have sufficient ventilation, into a warm roof which can lead to moisture damage and it also hides issues and leaks.
- RICS Spray Foam Insulation Consumer Guide
74
What guidance did you refer to when determining actions for the death watch beetle infestation?
BRE digest 307
75
What is roof spread?
Roof spread occurs when the downward pressure of the weight of the roof starts pushing against the rafters enough that the structure itself begins to move: either the roof starts moving downwards, or the walls start pushing outwards. This is a prolonged process but can cause severe damage to the integrity of a home.
76
What may cause a window to randomly smash?
Nickel sulphide inclusion.
77
What is cavity wall tie corrosion? How is it identified?
Wall tie failure is where the ties corrode resulting in expansion caused by the rusting process leading to cracking.
Horizontal cracks in the walls and bulging walls.
78
What are brick slips and the associated defects?
Specially manufactured tiles which when installed have the appearance, colour and texture of a real clay brick wall.
Brick slips debonded due to deterioration of adhesive. Expansion of materials adhered to leads to brick slips debonding.
79
Name some common defects for commercial properties?
- Regents Street Disease
- High alumina cement
- Carbonation
- Chloride attack
- Alkali silica reaction
- Woodwool slabs
80
Name some common defects for a flat roof?
- Crazing
- Ponding
- Thermal Movement
- Blistering
- Flashings
- People
- Cracks and tears
81
You are asked to inspect a flat roof, talk us through the inspection process?
- Arrange access
- Historical building information
- Prepare RAMS
- Identify age and condition of roof
- Repairs and any defects
- Inspection of rooms below
82
What is a protimeter / moisture meter?
A protimeter works by measuring the electrical resistance between two applied electrodes. Protimeters are generally used to monitor the moisture content in wood, therefore when used on other materials, the actual readings may be misleading but can give an wood moisture equivalent reading.
83
What is a speedy carbide meter?
A speedy carbide meter is a device to measure moisture in masonry through slow drilling masonry and putting dust into a sealed container with a known measurement of calcium carbide. It releases a gas in proportion to the amount of moisture present.
84
You are inspecting a building and identify a number of cracks in the external wall take me through your thought process?
I would firstly note the material the wall is constructed from and what form of
construction the building is. If there are any local factors which could be causing the
cracking such as trees or stumps, if there have been any alterations to the building, if there are drains in the vicinity of the crack. If there have been any alterations to the
building such as extensions, room in the roof or internal layout alterations.
85
Identify some other causes of cracking to walls?
- Subsidence
- Heave
- Settlement
- Differential settlement
- Thermal movement
- Lintel failure
- Wall tie failure
- Internal alterations
- Impact damage
86
What is nail fatigue?
The nails have rusted through allowing the slates or tiles to fall. It is usually that if one nail due to corrosion, then large sections could be at risk. The remedial measure would be to strip the roof and secure with new nails.
87
What is cut edge corrosion?
When the cut edges of coated metal cladding are exposed to the elements, for prolonged periods of time, delamination may occur in the form of peel back of the factory coating. The unprotected metal substrate then becomes exposed to rusting and corrosion.
88
Why is Japanese knotweed an issue?
The invasive root system and strong growth can damage to foundations and structures. The plant is resilient to cutting, vigorously re-sprouting from the roots.
89
What is chloride attack?
An additive used in the 1960s and 1970s to speed up the curing process. Can also be introduced by using sea water and unwashed aggregates in concrete.
90
What is high alumina cement?
An additive used to resist chemical attack from acids and to speed up the curing process. Used in pre cast concrete between the 1950s and 1970s. It increases the concrete's porosity which leads to loss of strength and reduction in resistance to chemical attack.
91
What is sulphate attack?
Reaction between sulphate and water leading to expansion. Likely to occur in ground bearing floor slabs and chimney sulphates from the flue gases.
92
What woods do the death watch beetle attack?
Hardwoods, such as oak and elm. Nutritious woods.
93
How can you tell if an older door is a fire door?
It should have a fire sticker or stamp or other form of identification.
94
What guidance is there for rot?
BRE digest 299 dry rot
BRE digest 345 wet rot
95
What are the negatives of using a protimeter on masonry rather than timber?
- Not wood so WME or conversion reading required.
- Metal conductivity could influence results.
- Surveyor using device may specify repairs without considering the underlying defect.
96
What did you specify to remove the corrosion?
Thorough clean, needle gun to remove rust and anti corrosion coating
97
What are the associated risks of corrosion to reinforcement?
- Affect the structual integrity of the building
98
Are there DPCs for Victorian properties? What are they and the associated defects?
Towards end of Victorian era slate DPCs were in use instead of bitumen. They were brittle with little flex so cracks allowing moisture to rise.
99
What is the technical term associated with rising damp?
Capillary action
100
Name some damp meter limitations?
- Equivalent reading if not wood.
- Conductivity of metal studwork affects prong reading.
- Misuse where true defect isnt diagnosed.
