Building Pathology Flashcards
1
Q
What is settlement ?
A
Settlement is the downward movement of the ground caused by a load consolidating the soil below it or causing displacement of the soil.
2
Q
What is sulfate attack in concrete?
A
A reaction between the concrete and the ground bearing slab where the presence of sulphates are within the hardcore/soil or introduced via water.
This creates a new compound that expands within the concrete to cause cracking.
Testing can be carried out via samples of the concrete and sub fill material.
Can take several years to come to fruition and is linked to coal mining areas.
Measures introduced include the selection of suitable materials, inclusion of a dpm.
3
Q
What is the Latin for dry rot ?
A
Serpula lacrymans
4
Q
What are the two forms of measurement provided by the protimeter?
A
Prongs = WME - Wood moisture equivalent.
Surface reading = Measured to a depth of about 19mm and a measure from 0-999
5
Q
What may give you false readings from a protimeter ?
A
Foil backed plasterboard
Salts within the brickwork.
Free water in brickwork.
6
Q
Can you give me some examples of causes of movement in buildings?
A
Subsidence, Heave, Thermal/shrinkage, structural failure.
7
Q
What are the ideal conditions for dry rot to spread?
A
Dry Rot requires wood as a food source. The fungus grows most rapidly on wood that has a moisture content around 20% though not saturated.
Dark, damp and poorly ventilated spaces are ideal conditions.
8
Q
For dry rot how far past the affected timber would you remove?
A
BRE digest 299 suggests 300-450 mm past the affected area.
Treat surrounding timber with preservatives.
If affected structural timber seek guidance from a structural engineer.
Sometimes it is necessary to seperate vulverable timbers frim ‘infected’ masonry.
9
Q
Can you expand on BRE 251?
A
This defines cracks and assessment of cracking from level 0, a hairline crack less than 0.1mm, up to structural damage cracks greater than 25mm.
The digest also recommend relevant remedial actions.
10
Q
What is subsidence?
A
The downward movement of ground due to chnages within the sub-soil.
This can be affected by the proximity of trees and drains or seasonal variations.
11
Q
What is frost heave?
A
Upward movement of the ground caused by water within the sub soil freezing and expanding.
Is common in places with high water tables.
12
Q
What are shrinkable clays?
A
Clays that are capable of absorbing and releasing large amounts of water, which can affect foundation movement.
13
Q
How can the removal of trees affect foundations?
A
Once a tree is removed, the sub soils absorb water that would have previously been absorbed by the tree. The sub soild expand and lead to ground swell or ground heave which can affect foundations.
14
Q
What is wall tie failure and how would you identify it ?
A
IDENTIFICATION — Horizontal cracking in every 5 or so brick course or in render. It’s the corrosion of old steel ties such as large fishtail. The corrosion increases the steel up to 4 times leading to the cracking.
REMEDY — use borescope to determine the defect is wall tie failure. Locate wall ties and isolate or removed to ensure no further damage. Install replacement stainless steel mechanical fixed ties secured with an epoxy resin if required
15
Q
What are the different types of rot and how would you identify them?
A
Dry Rot – Wood shrinks and splits into cuboidal cracks. Wood is light in weight when rot has taken hold ends up dry and crumbles under fingers. Usually mycelium on the surface which is grey when wet and yellow/purple when dry. cotton wool like/leathery skin. 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, but rare and occurs internally or externally.
16
Q
Can you expand on what trada tables are please ?
A
TRADA’s Span tables have been in existence for decades now, helping designer and builders quickly look up the right sized softwood members for domestic projects.
17
Q
What are the stages of dry rot ?
A
Spores
Hyphae
Mycelium
Fruiting Body
18
Q
What are the different types of common damp in buildings ?
A
Condensation
Rising damp
Penetrating damp
19
Q
How would you identity between dry and wet rot?
A
Dry rot is the most serious form of fungus decay in a building, spreads onto and destroys much of the timber.
On the other hand, the wet rot fungus occurs more frequently but is less serious, the decay is usually detained to where the timber becomes and stays wet.
The Wet rot fungus tends to grow on porous surfaces, for example, timber with a high moisture content of around 50% while for dry rot to grow moisture of around 20% needs to be present.
If left untreated wet rot can cause major structural problems as it can lead to weakened timbers.
For moisture content to be suitable for wet rot growth there has to be a source of constant moisture – this could be as a result of defective plumbing or damaged guttering.
Wet rot cannot spread through masonry and will cease to grow when the source of moisture is taken away.
Due to the parts of the building that tend to have the correct moisture levels, for example, underfloor areas, dry rot can often cause significant damage before the homeowner is aware that there is even a problem with dry rot in the property.
20
Q
What are wood boring insects and where can they usually be found?
A
A wood boring insect is a common term that covers many species of beetles that as larvae eat and destroy timbers.
Wood boring insects are usually found in areas within a property that are poorly ventilated with a high humidity such as for example a sub floor crawl space.
This is usually because these conditions become perfect for the larvae to hibernate and transform into a woodworm beetle.
21
Q
What are the the limitations of a protimeter?
A
Calibrated for timber only.
They are used to verify visual inspections and cannot be relied upon.
22
Q
What is a borescope and how do you use it?
A
A small instrusive camera used to inspect hard to reach areas.
Normally required to make a hole to view into a cavity as an example.
23
Q
What is fungal attack and what are the effects?
A
Fungi that attack timber in buildings. The effects can be loss of strength, loss of weight, change in colour.
24
Q
What is the moisture content in timber, required for dry rot?
A
Timber requires a moisture content of around 20/22% before dry rot can develop.
25
How can you identify dry rot?
Dry rot can appear in a variety of ways, depending on the stage of the infestation. Here are some signs of dry rot:
Mycelium: A white, cotton-wool-like substance that develops on the wood. It can also have grey or white strands.
Skin: A grey-whitish or silky skin that can be peeled off like a mushroom. It may have patches of lilac or yellow.
Cracks: The wood may crack in a cuboidal pattern. It will be dry and crumbly.
Darkening: The wood may darken in color.
Shrinking: The wood may shrink.
Fruiting bodies: A soft, fleshy, mushroom-like body that is often orangey in color with a rust-colored center.
Spores: Rust-colored spores that can be found in the affected area or around fruiting bodies.
26
How does Dry Rot spread?
Dry rot produces strands within the mycelium which feed the growth area.
The strands can travel over or through inert materials in the search for food.
27
What are the environmental conditions for Wet Rot?
Wet rot, a type of fungal decay, typically grows in timber with a moisture content of around 30–50% and generally requires a consistent source of moisture.
Wet rot can be caused by a number of things, including: Leaking roofs or gutters, Plumbing leaks, Condensation in poorly ventilated areas, and Rising damp.
28
What are the effects of Wet Rot?
While it's generally considered less serious than dry rot, wet rot can still weaken structural timbers and cause major damage if left untreated.
Wet rot is also different from dry rot in that it's usually confined to a damp area and doesn't spread, while dry rot can spread beyond its initial germination site.
29
How did you know that it was Wet Rot, in the loft area of Ditton Hill Road?
Within the loft there was a clear damp musty smell. When I saw the affected area, it was visually darker than the surrounding timbers. I tested this with a protimeter and the moisture content was around 50% and the timber was spongy in areas.
30
How did you advise the client to deal with the wet rot?
As I had located the cause, which was the failure of the lead valley gutter and detailing to chimney stack, I advised that this required addressing to eliminate the source.
The affected timbers should then be treated to prevent rot speading. A wood hardener could be used for timbers that were salvagable. However, any structurally affected timbers should be replaced.
I also advised the client to install additional ventilation tiles within the roof, to improve ventilation in the loft space.
31
What is the life cycle of an insect attack on timber?
Adult insect lays egg.
Larvae hatch.
Larvae tunnel into wood, eating it on their way.
Pupa forms.
Adult emerges through exist hole.
32
What are some common conditions for insect attack?
Insects generally tend to attack sapwood, rather than heartwood.
Usually in areas of dampness or with little ventilation.
33
What types of wood boring inspect might you expect to find in domestic dwellings in the UK?
Common Furniture Beetle.
House Longhorn Beetle.
Deathwatch Beetle.
Wood Boring Weevil.
34
Can you give me a examples of deleterious materials ?
Asbestos
HAC (High Alumina Cement)
Lead
35
Difference between wet and dry rot ?
Dry rot can penetrate masonry, different humidity, One of the main differences between wet rot and dry rot is that wet rot needs a higher moisture content to grow. Wet rot fungus likes to grow on timber with a high moisture content of around 50% and above while for dry rot to grow it will germinate at a lower timber moisture content of around 20% to 30%.
36
What indicators would you look out for if you suspect dry rot ?
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.
Dry rot often occurs in areas out of sight.
37
How would you advise the client on a like for like replacement of a timber floor structure affected by dry rot, talk me through the steps.
Consider the affected area
Remove affected timbers
introduction additional ventilation
rapidly dry out the area
trat area with a pesticide
replaced timber if splicing go 500mm past affected areas
protect joist ends form moisture ingress
38
Why is dry rot commonly referred to being more problematic than wet rot ?
As it can pass through masonry.
39
What typical building defects might you expect to see on a 1960s residential property?
Wood wall slabs
snapped headers
Stone defects
sulphate attack in concrete or chimney stack
damp penetration
timber attacks
lead paint
asbestos
shallow foundations to bays - differential movement
40
Where a property is suffering from subsidence, what type of cracking might you expect to see ?
Vertical, larger at the top than the bottom
41
When investigating structural cracking to brickwork in residential/low rise property what recognised standards would you refer to assist in classifying the cracking ?
BRE Digest 251 - Assessment of damage in low-rise budlings - This defines the inspection and cracking sizes to reference.
42
When investigating structural cracking to brickwork caused by adjacent trees what recognised standards would you refer to assist in assessing the risk posed by the trees present?
BRE Digest 298 - Low-rise building foundations - the influence of trees in clay soil
43
If a property was suffering from dry rot, what might you expect to see?
Dependant on the outbreak, a lack of ventilation.
You would see damage or cuboidal cracking to the affected timber.
Hyphae - fine white strands
Mycelium - a collection of mass of hyphae
fruiting body - mushroom like appearance rusty coloured.
releases the spores and the cycle starts again
44
How would you identify condensation in a property?
Consider the location and presence of damp, normally is low air flow/changes area, behind furniture, corners of room, near or adjacent to bathrooms and kitchens. Normally black spots.
45
Give some examples of the likely causes of penetrating damp.
Slipped slates
blocked gutters
failed tanking systems
Absent pointing
Render defects
46
What is nail fatigue?
That as a roof ages the fixings which are often nails start to fail resulting in tile or slate slippage especially in windy weather conditions.
47
What are the symptoms you might expect to find if a concrete floor was suffering from sulphate attack?
Cracking
Bulging
Movement on the walls above or below DPC
Unevenness to the floor
48
What is concrete Carbonation ?
Carbonation occurs when the alkaline elements of the concrete react with carbon dioxide creating calcium carbonate which lowers the PH level of the concrete which reduces the passivity. If there is inadequate coverage, the carbon dioxide can react with the protective coating on the steel and corrode it. Levels of carbonation impacted by compaction, temperature, humidity, carbon dioxide levels.
Identify by carrying out an onsite test that will change colour when it comes into contact with high alkaline concrete.
It is remedied by removing the delaminated concrete, cleaning the re-bar and patching the concrete.
49
What are common defects associated with flat roofs and what are the remedies ?
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 (1:40 min) 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.
50
What methods are you familiar with to assess flat roof defects?
Firstly, visually inspect the roof for any defects and then use a thermographic camera to identify colder areas that may identify areas of leaks.
51
What should you consider when deciding whether to repair or replace a flat roof ?
The extent of the defect, when the existing roof was recovered, the approximate life span, the cost, timing, clients intentions for the building.
52
What are the possible causes of sagging roof ridges and possible secondary problems ?
Decay to the timber forming the structure, inadequate supports or alterations carried out to the structure. Change of roof coverings.
Secondary problems may be slipped tiles or opening joints at the ridge allowing water ingress.
53
What is damp ?
A building is considered damp if moisture becomes visible through discoloration of finishes or causes mould growth, sulphate attack, frost damage or puddles and drips.
54
What is a protimeter / moisture meter ?
Measures the electrical resistance between two electrodes. Generally used for moisture in wood.
55
What is a speedy carbide meter?
Measures moisture in masonry through adding masonry dust into a container with calcium carbide which releases a gas in proportion to the moisture present.
56
Describe three issues and remedies for rising damp.
Rising damp can be caused by; a lack of a DPC, a defective DPC or a bridged DPC.
The remedies can be:
- removing the cause of bridging which may involve reducing the ground level.
- It may be necessary to fit a new physical DPC or in some circumstances an injected DPM.
- Alternatively, a lime plaster and wash may be suitable.
57
What is cold bridging?
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.
58
How would you identify condensation? What are the remedial measures ?
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, improving insulation and maintaining a regular internal temperature.
59
How long would you leave brick/plaster to dry out before commencing work ?
Generally should be left for 3-4 months but this is not always practical.
60
How would you tell the difference between rising damp and condensation with a moisture meter ?
Rising damp generally only occurs to the bottom 1m of the wall. Test the moisture in the wall at 300mm intervals. If it is closer to the ceiling, odds are that it is condensation particularly if there is a mildew on the surface.
61
You are inspecting a building and identify several cracks in the external wall. Take me through your thought process.
Firstly, what is the building made from and what is the construction method?
Are there local factors such as trees, stumps or high water tables?
Have any alterations been carried out?
Are there any nearby drains?
What has the weather been like in recent months?
What is the age of the building?
62
What types of soil is susceptible to heave and what are the possible causes?
Cohesive soils such as clay. Could be because of trees or high water table, leaking drains etc.
63
Deflected timber floor in early 19th Century building. What methods are available to deal with this if the client requires a level floor ?
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.
64
What does Japanese knotweed look like ?
Hollow stems with raised nodes with a similar appearance to bamboo.
Can reach 3-4m per year.
Broad oval leaves with small white flowers
65
A newly cast reinforced concrete slab is exhibiting crazing and cracking on its surface. What are the causes ?
Poor or inadequate curing caused by 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.
66
Why is Japanese Knotweed and issue ?
Invasive species which forms thick colonies that crowd and kill other species.
It can extend 7m horizontally and 3m deep making excavations difficult.
The plant is resilient to normal weed killers and cutting. It requires herbicide application to kill it, over a period of months.
The strong growth can cause damage to foundations and structures.
67
What typical defects are associated with Victorian terraced houses ?
Failed on lack of DPC
Insufficient foundations
Poor ventilation to floor voids
Damp penetration
Lead pipework.
Over notching to floor joists.
Overlaoding of roof structure.
68
What are the causes of staining to chimney breasts and the remedial work required ?
Sulphate attack
Defective flashing
Removal of stack below
69
What are the likely causes of a leaning chimney breasts and what are the remedial works ?
Erosion, acid attack, salt crystallisation could all cause the stack to lean.
BRE Guide states any lean of the stack of more than 1 in 100mm is unsafe.
Consider lining the flue with a liner and replace broken bricks and pots.
Reflaunch the top if needed. Worst case scenario rebuild the stack.
70
Name some typical defects of a Georgian building (1700’s) ?
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
71
What is rising damp ?
Upward movement of moisture through permeable building materials such as brick by capillary action.
It rises up the wall often to a height no more than 1.5m and usually leaves a characteristic horizontal tide mark.
72
What is condensation ?
Moisture in the air (water vapour) is held in high temperature air and when it comes into contact with a cold surface it is cooled, and excess vapour condenses (dew point).
73
What is wall tie failure ?
Wall tie failure can happen where there has been corrosion of the existing wall ties or when insufficient or incorrect wall ties have been installed.
When a mild steel or galvanised steel wall tie corrodes, there is a build up of rust (also known as iron oxide), which causes the tie to expand in size.
74
If you identified movement in a building, what further investigations might you wish to undertake?
Consider the location
Recent works
Construction of the building
Type of the cracking
Opening up works
Further investigations
75
Explain how you could use thermal imaging to identify heat loss in a building ?
Thermography uses specially designed infrared video or still cameras to make images (called thermograms) that show surface heat variations.
They can also be used to identify water ingress.
76
What are some limitations of thermal imaging cameras when used in home surveys.
Weather
Cold, windy, or rainy days can cause false positives or inaccurate readings.
Time of day
Solar heating can affect readings during the day, so it's best to wait at least two hours after the sun has set.
Surface conditions
Moisture, condensation, or damp surfaces can distort readings.
Reflective surfaces
Shiny or reflective surfaces, like glass or metal, can create inaccurate readings.
77
What are some common defects in pitched roofs?
Incorrect pitch and guage, nail sickness, overloading structure causing dishing or deflection, roof spread caused by incorrect rafters and no restraints, delamination of tiles and poor flashing details.
78
What are some factors that should be considered when chooing an approriate foundation?
The building load.
The type of sub-soil.
Previous use of the land.
The water table.
Sulphate attack.
Surrounding elementes e.g drains and trees.
79
What are cohesive soils?
Small particles that cling together and have a high water content, often have a smooth and sticky feel - such as clay.
80
What are non-cohesive soils?
Large particles which are helf together by their weight. They contain small amounts of water. They are loose in structure, such as sands and gravels.
81
What are some of the best practice installation techniques for lead?
Lead should not be laid in lengths longer than 1.5m and should be lapped by 150mm.
Soakers should have a minium 75mm upturn against a wall and 100mm over a tile.
82
What is a cold roof construction?
Cold roofs are formed with insulation between the roof joists, and have a 500 ventilation gap above to allow airflow to the void.
A vapor control layer should be placed between the insulation and the plasterboard
83
What is the pitch of a flat roof?
10 degrees or less.
84
What is a warm roof construction?
A warm roof is formed by placing insulation on top of the roof structure.
A vapor control layer should be placed between the insulation and timber sub-deck.
85
What are some common failures of felt roofs?
Blistering.
Poor termination.
Insufficient laps.
86
What are some common failures of single ply roofs?
Single ply is made from synthetic polymers and are around 1.1-2mm thick, so very thin.
Common defects include:
Punctures - it is easy to puncture.
Shrinkage - It looses elesticity with age.
Seams are more vulnerable to leaks than other systems.
87
What are some common failures of asphalt roofs?
Blistering.
Reliant on the substrate, so any movement can cause cracks.
Surface cracking and sagging from thermal changes.
Loss of elasticity with age, can lead to cracks at upstands.
88
What are some common reasons why render fails?
Poor surface preparation: If the substrate isn't properly cleaned, degreased, and sanded, the render may not adhere properly.
Incorrect mix proportions: Poor mixing ratios and low quality materials can cause render to fail.
Incorrect application: Applying the render too thickly or in layers with a high moisture content can lead to shrinkage and cracking.
Inadequate curing times: Inadequate curing times can result in weakness, ultimately causing the render to crack.
Exposure to harsh weather conditions: Render can fail if exposed to harsh weather conditions.
Small movement in the foundations: Small movement in the foundations of your home or building can cause hairline cracks in your render.
Moisture is seeping through the render: High levels of damp within the walls can cause hairline fractures that can eventually lead to the failure of the render.
89
What are the disadvantages of sand and cement render?
Cracking
Sand and cement render can crack due to shrinkage in the render or the underlying masonry, or due to thermal movement. Cracks can allow moisture in, which can lead to damp issues, mold growth, and structural damage.
Reduced breathability
Sand and cement render is less breathable than other options, like lime render. This can trap moisture in older buildings or buildings made with materials that need moisture to pass through.
Quality issues
The quality of the sand and cement can affect the durability of the render. The mixture ratio can also impact the quality and durability.
Application
If the mixture is applied incorrectly, the render will crack. The walls must be clean and dry before applying the render so it binds firmly.
90
What is monocouche render?
Monocouche render is a decorative, breathable, and weather-resistant exterior finish for buildings that's applied in a single layer.
91
What are some common causes for cracking in walls and foundations?
Initial settlement.
Subsidence.
Fronst heave.
Shrinkable Clays.
Removal of trees.
Leaking drains.
Sulphate attack.
92
What are some common causes of movement in walls?
Inadequate thickness.
Lack of restraint or support.
Thrust.
Excessive laoding.
Loss of bonding.
Thermal movement.
Moisture movement.
Corrosion of steel or iron components.
Failure of arches or lintels.
93
What is relative humidity?
The amount of water vapur present in air, as a percentage of the amount needed to achieve saturation at the same temperature.
Or, a measure of the water vapour content of air.
94
What is interstitial condensation?
Condensation that occurs between layers of the construction, i.e inside the roof, wall or floor elements.
95
What can you tell me about the joint position statement?
It is a document that outlines the principles and competencies needed to deliver best practice when investigating moisture related issues, in traditional buildings.
96
How would you fix cavity wall tie failure?
After confiming the issue is a wall tie failure, but opening up or using a borescope, I would then look to locate the individual wall ties and remove them.
Installing replacement stainless steel mechanically fixed ties secured with an epoxy resin.
97
If there was stepped cracking on the corner of a building, what might have caused it?
Settlement.
Subsidence.
Heave.
98
What size cracks are of a concern?
With reference to Digest 251:
Up to 2mm - very slight concern.
2mm - 5mm - slight aesthetic concern.
5mm - 15mm - Moderate concern.
15mm - 25mm - Severe.
Over 25mm - Very severe with stability concerns.
99
What should you consider if you notice cracks present in concrete?
I would consider the common concrete defects such as Carbonation, Chloride attack and silica reaction as well as issues relating to structural movement and poor design and constructio.
100
How do you identify the presence of woodworm?
Holes in the wood, with live infestations showing powder arund the holes.
Typically 1 - 1.5mm
101
What is a woodworm infestation likely to indicate?
A higher moisture content than is normally found in a typical home or potentially excess damp.
102
How is a woodworm infestation treated?
It can be controlled with chemical insecticides.
The original damp issues should also be investigated.
103
You are surveying a deflected timber floor in an early 19th century building. What are the causes and methods available to deal with this, if the client requires a level floor?
The potential causes of a deflected timber floor are:
- Notching
- Rot
- Insufficiently sized joists
- Insufficient centres
- Overloading
- Deterioration of sleeper walls
The options to form a level floor would include:
- Supplement the timber joists with additional joists.
- Overboard the existing joists.
- Remove and replace with a new suspended timber floor.
- Install an alternative solid floor.
104
You are notified of a leak at high level on the first floor of a 2 storey building constructed with a traditional cavity wall construction. Please outline the process which you would go through in assessing the cause of the defect. Also, what are the potential causes of such a defect?
I would firstly review any existing building information available before inspecting.
I would then assess the building holistically, to understand the construction and materials used, including as amendments.
I would speak with the owner or occupier to understand the background of the leak and when it may be most prevalent.
My first thought would be the roof, so I would inspect externally and internally. I would also look for evidence of leaking pipes in the loft.
105
What are the four typical treatment methods for Japanese Knotweed?
Excavation - Digging out and removing all.
Mechanical disturbance - Not an eradication method, but makes the knotweed more susceptible to other treatments.
Root Barriers - Barriers are used to contain the JK.
Herbicide control - Regular use of herbicides over seasons, to kill off the plant.
106
When the movement of a wall exceeds one third of the walls thickness, what would you recommend?
If the wall have moved or bowed more than one third of the walls thickness, I would recommend that the wall is rebuilt.
