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This has now bee withdrawn  but many BBA agrèment certificates continue to make reference to this standard, where compliance with the BBA certificate is seen is proof of building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