External Insulation + Damp + Flat Roof

karlitob

Hi all,

You're help if you please.

We recently got external insulation put on the top half of our house. The bottom half has an extension so we went with internal insulation. We have an area of damp (with mould) at the spot where the flatroof of the extension meets the wall of the house. At the same point is the down pipe from the toilet. Since we couldnt move the downpipe, the external insulators allowed an alcove in the insulation to accommodate the down pipe. All internal plumbing is intact and not leaking. That leaves three options

- downpipe from toilet is cracked. But, our problems only started getting worse in the last 6 weeks and not for the past year, if the pipe was burst then the damp wouldve started earlier.

- the seal in flat roof/house has been damaged. Again, I don't think this is it and nothing was done in the area that could've caused this.

- transfer of water from area of cold to an area of warm. ie since there is a gap in the external insulation, then when the house is warmer on the inside it draws water in causing damp.

I guess my question is does all that sound reasonable. Any other ideas? Suggestions? Can water really be drawn in from outside despite no damage to the house seals?

Thanks

MicktheMan

Probable cause : Severe thermal bridge resulting in localised internal cold surface causing continuous condensation (i.e. moisture) which mould needs to thrive.

Any pics?

A physical damp survey should be able to isolate the source of the problem and offer solution(s).

karlitob

MicktheMan wrote: »

Probable cause : Severe thermal bridge resulting in localised internal cold surface causing continuous condensation (i.e. moisture) which mould needs to thrive.

Any pics?

A physical damp survey should be able to isolate the source of the problem and offer solution(s).

I can get a couple of pics for you this week. But I really am worried that you might be right - any suggestions? on treatment? Could I literally blast that gap with external insulation - I wouldn't care about how it looks.

MicktheMan

karlitob wrote: »

I can get a couple of pics for you this week. But I really am worried that you might be right - any suggestions? on treatment? Could I literally blast that gap with external insulation - I wouldn't care about how it looks.

As I said, the possible solutions would come from a full proper physical survey.
Any "blasting" of anything may well make the situation worse.
Have you contacted your ewi contractor / builder and why couldn't you/they move the downpipe when installing the ewi?

karlitob

MicktheMan wrote: »

As I said, the possible solutions would come from a full proper physical survey.
Any "blasting" of anything may well make the situation worse.
Have you contacted your ewi contractor / builder and why couldn't you/they move the downpipe when installing the ewi?

Yep I have, he's coming out again during the week. Usual stuff of not being their fault - 'they simply put it on the wall'. Because the downpipe drops through the extension roof (surrounded by a drywall box). If they went at it, it couldve damaged the extension flat roof.


Who would do the physical survey?

Thanks for all your help.

MicktheMan

karlitob wrote: »

Yep I have, he's coming out again during the week. Usual stuff of not being their fault - 'they simply put it on the wall'. Because the downpipe drops through the extension roof (surrounded by a drywall box). If they went at it, it couldve damaged the extension flat roof.


Who would do the physical survey?

Thanks for all your help.

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