Cause of damp on internal walls

Doozergirl

The original house is higher than the extension? Do you have a suspended wood floor in the original house? If so, how is the subfloor being ventilated at the back of the original house?

I know these are 'internal' walls now, but pictures of outside areas around those walls are helpful. Ground and roof level. You won't easily diagnose from looking at the symptoms.

adidas

Hello, thanks so much for all your replies. Yes the extension has stairs below ground level of the original house. The 'damp' patch area does not extend to the floor of the extension. It is at the level of the first step. The worst affected side is on the 'semi-detached side' so will try my best to look at this bit but might be hidden into neighbours garden. Will try to take some pics when I can to illustrate the outside as well.

Wondered if you could help me....I don't remember the house survey saying that I had a suspended floor but will double check. Is there any other way I can tell?

I'm looking around the kitchen and can't see any ventilation vents.

adidas

Here are some further photos:


Where the guttering is on the outside is not immediately adjacent to the internal wall that has the 'damp' bit on. There's no damp in the corner that has the guttering on the other side. The other side of the wall on this side is where the old kitchen is and has been converted to a utility type room and there is lots of shelving fixed to the wall so I can't see around this.


http://s304.photobucket.com/user/huhugy/Mobile%20Uploads/story

adidas

*bump* Any ideas? Also I think it is indeed a suspended floor

Doozergirl

So, if it is a suspended floor, it has to be ventilated. Under that floor is a damp area which needs airflow to keep it moving, not trapped. You should have airbricks to front and back.

If you build an extension to a suspended floor, it still needs ventilating. You should do this during the build. Bit too late bow.

I suggest at the very least putting more airbricks to whatever is still left outside of the original external wall and other external walls, where available.

I can't really fathom what you have there but perhaps get a builder out to look at how ventilation can be improved discreetly to the area that is now covered internally as well - ie. where you have some dampness creeping.

adidas

Thanks for that, will save it up on my jobs list and have a builder attack these all at once!