Cavity Wall Insulation
Condition Inspection Surveys
If your property didn’t get a proper cavity wall insulation installation, damp problems, damp smells, cold spots, mould, and other tell-tale signs may already be present or be lurking unknown to the house owner and may not show for some time. The damage that can be caused by failed cavity wall insulation can cost thousands of pounds to put right and can seriously affect the value of your house and your home.
Needless to say, if the cavity wall insulation is compromised or has failed, it will not be effective in providing the advised 33% heating energy savings and if it is wet, it could actually be having the opposite effect and costing you more to heat your home.
Oscar Onsite can help you identify these issues in a bespoke onsite survey which has been compiled by OSCAR and our Chartered Surveyor partners.
If you’re living in or intending to buy a property that has cavity wall insulation installed, it’s worth considering the long-term effects on the property and potentially its value. The results may surprise you. It is estimated that up to 6 million of the 17 million houses that have been installed with retro-fit CWI have failed or have faults and can cause damage to the house and will need to be extracted. Oscar Onsite are now working with homeowners and tenants across England & Wales to provide technical assistance in relation to retrofit insulation measures and provide an in-depth technical assessment and survey reporting service. The scale of the Cavity Wall Insulation problem was discussed in Parliament in November 2016.
Oscar Onsite is the UK’s Leading Authority in Cavity Wall Insulation Surveying and Extraction and their RICS Partners and Chartered Surveyors. They understand the insulation process more than anyone and particularly Cavity Wall Insulation, to identify its current condition, if it has reached the end of its life span or has failed due to a variety of reasons, and identify any areas that have contributed to its failure that should be remediated if you intend to have the latest cavity wall insulation reinstalled.
A specific Cavity Wall Insulation Condition Inspection Survey involves a visual building inspection and an invasive inspection into the cavities to see exactly what is going on using specialist borescope equipment. It requires an amount of time spent at the property, an in-depth assessment of the building’s performance and identifiable defects and produces a detailed report which is secondary checked to ensure it is 100% accurate.
The ability to drill into a cavity in multiple locations provides a surveyor with valuable information and photographic evidence as to the performance of the Cavity Wall Insulation and condition of the cavity throughout, identifying problematic issues such as rubble in the cavity or voids. There is a wealth of information a surveyor will collect.
If you suspect that the performance of the Cavity Wall Insulation may be compromised, the following points should be considered by your surveyor plus many other factors and investigations:
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- Exposure to walls from wind driven rain
- Drill patterns of the installation
- Size and condition of drill holes
- Cavity trays and weep holes
- Brushing off between properties
- Location of internal dampness, mould and/or condensation
- Type of insulation
- Overall wall thickness
- Location and condition of damp proof course
- Internal temperature and relative humidity
- Voids in the insulation
- Spalled brickwork
- Deteriorated pointing between bricks
Exposure to walls from wind driven rain
Areas across the UK are zoned into exposure areas of 1, 2, 3 and 4, much depending on wind driven rain. Your home is exposed to severe levels of wind-driven rain if your home is located in an unsheltered position, e.g. not protected by trees or other buildings
Drill patterns of the installation
The drill pattern is the tested process that the BBA state in the install license that says CWI should be installed by drilling holes in a recognised pattern to ensure a proper and adequate fill. Any variation from the drill pattern may contribute to CWI failure.
Size and condition of drill holes
Drill holes should be a standard size and once the CWI is installed, these holes should be sealed up properly and ensure no water can enter the cavity and into the insulation causing it to get wet.
Cavity trays and weep holes
Whichever cavity tray construction is used, weepholes are required. At least two weepholes must be provided to cavity trays above openings and pre-formed “weeps” should always be used at maximum 900mm centres and always be positioned at stop ends.
Brushing off between properties
Cavity wall insulation brushes are used as the ideal solution to separate the cavity at the party wall prior to filling with blown cavity wall insulation. This ensures the fill is full and there is no leakage of insulation outside the insulated area or causing trespass to your neighbours’ walls.
Location of internal dampness, mould and/or condensation
Where damp is found internally, this is usually the best area to investigate on the outside of the building relative to where the damp is showing.
Type of insulation
Three main types of retrofit insulation used across the UK are blown fibre, blown wool and foam.
Overall wall thickness
The thickness of a wall and the depth of the cavities also play a big role in assessing a property to see if it is suitable for cavity wall insulation to be installed, and to what amount of insulation is required to achieve the correct thickness and density to gain a proper install.
Location and condition of damp proof course
A damp course should be at least 150mm from the ground consistently all around the property. 150mm is usually the height of 3 bricks. If a damp course is less than this, a property might suffer from rising damp which can severely affect the insulation and cause it to get wet and fail.
Internal temperature and relative humidity
A good install of cavity wall insulation should also ensure that sufficient ventilation is allowed through wall vents and sub-floor vents. On many occasions, these vents were sealed with silicone meaning the insulation and property cannot breathe. Any moisture ingress cannot escape, and can cause severe problems inside the cavities and inside the property.
Voids in the insulation
Voids in insulation mean there are holes of any size in the insulation which can cause warm moist air to meet cold air which can cause condensation, damp spots and mould.
Bricks are porous and spalled brickwork where the front of the bricks are damaged and cracked will allow water to penetrate far easier and ultimately allow water to penetrate into the cavities and into the insulation.
Deteriorated pointing between bricks
Small hairline cracks in the pointing between bricks can allow water ingress to the cavities and again allow the insulation to get wet and transfer water to the inside of the property.
Where a surveyor will be able to view the cavity and identify any voids, damp, rubble, sagging or other issues, a judgement can be made on the performance of the Cavity Wall Insulation. With reference to technical documents (e.g., BBA system certificate), the report can give accurate information to assist homeowners and ultimately aim to prevent damage to the property, and the report may suggest the insulation is fully extracted to limit further damage.
Even where the Cavity Wall Insulation may seem to be performing without any problems, homeowners will often request guidance on living with Cavity Wall Insulation now and in the future, knowing now that so many CWI installs have failed, prevention is better than cure.
Many conveyancing solicitors now require a copy of any CWI guarantees be held on file as part of the home buying process, given the reported large number of properties that are reported to have CWI failure.
A sound and proper install of Cavity Wall Insulation into a property that is suitable can achieve the promised 33% heating energy savings, which is a massive saving, year in year out for a 25-year period. Combine that with sound and effective Loft Insulation, and your heating energy savings can be almost halved.
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