Protruding DPC

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I'm slowly getting there in this long saga documenting the poor standard of CWI installed into our 1930s property. But over a year later and I'm still finding very basic examples of poor workmanship.
This one is somewhat subtle but demonstrates why pumping in installation with minimal understanding of the building fabric is utterly reckless. 

It has become apparent that the external DPC protrudes into the cavity and it does so in all the walls of the old part of house as illustrated in the diagram below. The DPC has a mortar bed on top of it which makes it very rigid and acts as a pinch point capable of snagging large pieces of bricks and mortar as they drop into the cavity, holding them against the internal wall above the DPC level.



The impact of CWI on a protruding DPC

The presence of such debris causes a thermal bridge (condensation spot risk) to the internal wall quite a few bricks up from the internal DPC and so any moisture that enters the cavity has the potential to drip back towards the internal walls.

The problem is that when installing CWI though a  a thick render, the house is peppered with drill holes , supposedly to the BBA certificate standard. This is a destructive process by it's random natrure which can knock off brick faces faces and  corners into the cavity.
Again acting as a pinch point, the DPC will jam any large debris against the internal wall.

CIGA are aware of the messy nature of dealing with rendered walls and addressed it in their Best practice for complain handling.
Guide to Best Practice for Complaint Handling v7 Oct 2015

In our case CIGA inspectors did not assess the base of the cavity around the DPC. I have provided photos of the cavity with these bridges and they have said that all the problems are due to maintenance which is the standard nonsensical nonsense from them. 

CIGA also lied about the drill hole patterns measurements which they did not in fact measure at all and I have had the holes independently verified as not being to the BBA certificate specification.




Protruding DPC, wedged cold bridging debris and voids. This is prevalent throughout the property.




This all has an impact on extraction as fishing out all this debris means removing more bricks and the extraction process of a rendered surface often involves further debris falling into the cavity which will again collect at the DPC.
What a mess in work 'Guaranteed by CIGA'.

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