Impermeable paint and condensation analysis

-
The most popular post on this blog  details the problems of blocking the cavity with insulation in the presence of impermeable paint/render. Here

To recap the events since. Energy Saving Trust had provided me with technical guidance regarding the likely problems :  
"It is certainly the case that adding a coat of paint or other material with lower vapour permeability to a wall with relatively high permeability will affect the way moisture can travel through the wall. It is also the case that adding insulation to a wall at any point will also affect the way moisture behaves and travels within the wall.
If the wall has been externally painted with a low permeability material, then these guidelines may not be sufficient to minimise risk of unintended consequences, and so we advise that the pre insulation survey takes full account of the situation, and the likely behaviour of moisture in the wall post insulation."

EST also stated that it's CIGA's responsibility to assess and advise on the problem but CIGA's entire reply on the issue was:

"Yes we have followed up the EST logo issue even though it is a red herring in the scheme of things. CIGA takes on board their comments regarding the technical assessment process but again cannot be taken into isolation with considering other factors. "  -  Head of customer Services, CIGA.

It turns out that although CIGA's usual dodge of a response implies a certain ignorance to the issue but the truth actually points to  negligence. They would have known very well that assessment of the building fabric including paint layers was part of the assessment required by the building regulations because there has been an existing British Standard for assessing suitability of cavity walls since 1985.

Until around 2010 the British Standards which formed part of the building regulations dealing with retrofit cavity wall insulation was "BS8208:1985 Guide to the Assessment of suitability of external cavity walls for filling with insulants – Part 1 Existing Traditional Cavity Wall Construction."

This has now bee withdrawn  but many BBA agrèment certificates continue to make reference to this standard, where compliance with the BBA certificate is seen is proof of building regulation compliance.

Clause 8 of this standard makes it very clear that specialist advice is required in assessing the permeability of exterior coatings.




CIGA simply ignored our request to consider this forcing us to have the condensation analysis done for our house by a qualified professional. The analysis clearly shows the risk of interstitial condensation at the masonry render interface which the surveyor concludes would be trapped due to the impermeable paint and susceptible to freeze thaw cycles and ultimately render and masonry cracking.

Part of the condensation analysis based on idealised (clear) 50mm cavity.

CIGA cannot claim ignorance as their head of inspections claims 40 or more years in the industry much of which would have been working under BS8208:1985.  CIGA inspectors have no formal qualifications or oversight to do a such building defect or condensation analysis but all should be aware of this British standard which leads me to believe that they deliberately avoided considering this issue when inspecting  our house in order to avoid paying out on their guarantee. This was even after I provided them with the EST guidance. (bearing in mind that EST are listed as partners on the CIGA guarantee).

So again further evidence of CIGA picking and choosing what to inspect and failing to followup on basic building regulations in favour of taking photos of unrelated building defects in which to lazily shift blame to the home owner. A completely lack of probity.

What happened to BS8208:1985- part 1

I mentioned that this standard was withdrawn in 2009. So what replaced it?
It seems that there is no replacement - it is assumed that CIGA's installers guides and the BBA certificate are sufficient.
The PAS2030-2035 may offer some additional safeguards such as ventilation and more holistic assessment of building needs but it seems that oversight of the building regulations has been completely devolved to a company who not only runs the competent person scheme but also the 25 year guarantee.

How can a CIGA inspector be objective knowing that if they do actively inspect or document failures to meet the BBA certificate then their boss will get mad because he has to pay out on the guarantee.  A huge conflict of interest.


Comments

Post a Comment

Popular posts from this blog

The controversy over Cavity Wall Insulation 'topups'

-
Image
In this article I talk about the practice and problems of topping up insulation when voids are discovered, why it is being done and the potential violations of building regulations. I can only put forwards what I have understood from public documents and personal correspondence  So I welcome corrections or clarifications from the industry on this important issue for home owners and will happily update this post to reflect any inaccurate statements. We know that 100s of topups are done every year.   From what I can gather : If the BBA have not approved these topups then the relevant local authority building control should have been notified prior to topping up as an 'off licence' use of the product.  It is not clear that the correct procedures are being followed in all cases. Background :Voids are common A void is simply an area cavity between the walls which is missing insulation.  If a void is large enough then the insulation will not be compliant with the meter square
Read more

Lintels, weep holes and render

-
Image
I found the notion of lintels in cavity trays difficult to visualise. The reason I'm looking into lintels is that there is a damp patch that runs along the lintel over the front door. Brick houses built today will have cavity trays and weep holes inserted into the design. You will spot weep holes these as either gaps in the mortar or where the mortar is replaced with a perforated plastic insert as below. CIGA state that no water should enter the cavity is properly maintained building. If that is so then why does building control mandate a cavity tray. Typical modern cavity tray with weep holes sitting on a steel lintel. The purpose of a cavity tray is to ensure moisture that gets in the cavity when driven through the mortar joints or other means is directed back to the outside wall and out of the building. If you didn't have a cavity tray or some sort of damp proof course then moisture would collect on the flat lintel and then flow off the sides of the lintel or soa
Read more

Discrepancies between Internal and external DPC (damp proof course)

-
Image
In a cavity wall construction, one would expect that the damp proof membrane to be at the same level on both walls. It turns out this is not always the case and my house is a good example where the internal wall's DPC is more than a brick lower than the external wall DPC. I didn't even think to check this before reading the CIGA Technical note 14 . This clearly states that if the distance between DPC and ground level is within a brick (as was the case with my property at time of install) then 'numerous other factors' must be assessed before declaring the dwelling as being suitable for CWI. CIGA  Technical note 14 . One of the factors is the relative level of the inner and outer leaf DPC. This is exactly what I found in my property. Ive used a floorboard to show the position of the internal floor. The DPC is clearly a brick below the floorboard and less than brick above the block paving. External leaf DPC is 1 brick below the floor level.
Read more