Damp Proofing Question

Solid floor extension without air bricks for raised timber floor


We have a single story extension across the rear of the house built by the previous owner (we think about 10 years ago). The extension has a solid floor that butts up to the raised floor of the original building. The house is a 2 floor 1930s semi.

I've come to decorate the rear room that joins on to this solid floor and after raising the carpet noticed a musty smell. I lifted a couple of floorboards in the corner near the floor and noticed the ground was damp (which we expected as everyone else on the road gets this due to high water level/being at the bottom of a hill). The thing that concerned me is that what looks like condensation/water droplets at the end of a joist near the party wall - I believe this is due to the lack of air flow underneath the rear of the building. The joist still appears solid and looks like it is sitting on brick with a rubber mat (dpm?) and some slate.

What would be my options here? Would I have to excavate the kitchen floor to lay ducting (which sounds expensive and messy!) or is there another way?


1 Answer

Best Answer

the condensation will be forming here as there is a temperature change. i would insulate between the joists with rockwool and support it with plastic sheeting this will stop the moisture build up on the underside of the floor and joists.
plus save you money on your heating. a couple more air bricks on the available walls would help also

Answered 11th Nov 2012

jd kent

Member since 14 Jun 2008

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