At the risk of entering the 'most obvious question of the year'competition within the final 10 days I have a question regarding thelikely cause of damp and, more importantly, the best way to 'cure'it...My Victorian (1905) terrace has a double skinned (not sure if it's gota cavity as such, were they built like this?) rear wall that isrendered and has a Tyrolean top coat.We have recently noticed signs of damp inside a dining room cupboard,mounted on the rear wall, and initially put this down to the lowtemperature inside the cupboard (~12-14C) due to the rear wallposition. However, it then dawned on me that temperature alone ispresumably not sufficient to cause damp, water is required for this,and so given that the kitchen/dining room is well ventilated (okay, thecupboard isn't) and there are no signs of damp anywhere else in theroom/house then it must be coming in from outside.Looking at the back wall there are no obvious signs of a way in for thewater, no cracks and no dodgy gutters/downpipes. However, knocking onthe render around the area of the cupboard sounds hollow.Thus, my competition entry question is: Does that fact that the renderhas blown mean this is likely to be the cause of water ingress and,ultimately, the cause of the damp? If so, how does this happen?Presumably there may well be hairline cracks that I can't see and theblown render traps a layer of water against the bricks which eventuallyseeps through to the inside?If my assumptions are correct, what is the best remedial action, bothshort and long term (i.e. before/after Christmas!)? Replacement willpresumably be the long term fix - it's a small enough area that I'mmore than happy to do it myself - but what with? Would it be worthwhileremoving the blown render in the short term, or will the bare bricksthen suffer just as badly? Should the bricks, before rendering, be'treated' with anything? Does the render on these old houses serve to'waterproof' the wall, or is it largely decorative?Grateful for any...

Depends where you are. Up here on a hilltop in Scotland, there's absolutely no doubt!May I add a related question?Rusting and swelling of old iron downpipe fixing spikes is a known cause of cracked render, and our house is a perfect example. But when removing these spikes, they tend to snap off in the bottoms of the holes. Is it OK to fill over the deeply buried bits... or is that storing up trouble for later?In other words, does it need a simple filling or the full root canal?

I wonder why.you just confirmed what I said.:)NT

tell those that own such places.NT

Blown render = likely cause of damp?

Dec 22, 2005 21 Replies

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meow2222 20 years ago

I wonder why.

you just confirmed what I said.

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meow2222 20 years ago

tell those that own such places.

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