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External type A Liquid applied membrane - holes?


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Posted

I'm applying an external liquid applied membrane (bituminous) to the reinforced concrete walls of my new basement. Problem is, there are thousands of very small holes in the otherwise smooth surface finish, presumably tiny air bubbles a few mm across.

When I apply the waterproofing, these holes do not fill, I hadn't noticed them before applying the waterproofing as they are very small. I've tried brushing and rolling and nothing will reliably fill them with the paint.

 

What to do?

 

AI suggests a tanking slurry. I am sceptical that this will fill these holes as they seem bigger inside than the part that breaks the surface.

I don't really want to switch to a membrane as that seems a lot of work.

 

I'm not too worried about the effectiveness of this layer. I have waterproof concrete which appears to be sound and carries a warranty, the basement is walkout so totally above ground on 2 of the 4 sides, and will have free draining backfill and a land drain, so it is unlikely to see a head of water ever. I'm really only applying the type A because I thought it would be easier to apply it than persuade a "waterproofing designer" that it wasn't required, even though BS8102 does allow just one system in my situation. But if i'm going to the trouble of applying it, it would be nice to do it properly.

 

Can anyone suggest any ideas? It feels like a liquid applied type A is fundamentally unsuited to reinforced concrete, but I think it is very commonly used.

Posted

Spraying or trowelling/floating the stuff on usually minimises these “bubbles” - not air but indentations in concrete surface and roller cannot push the liquid into the hole. Not a problem if over layering with a mechanical membrane but not good with liquid alone. Stippling with a brush usually works but a pain on larger surfaces.

Posted

Thanks for the ideas. Not easy to get a suitable sprayer it turns out.

 

Fortunately the part has gone on much better, for some reason yesterday's old roller (stored airtight) which doesn't roll so well anymore seemed to do the trick!

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