Damp Proofing Question

Ventilating a concrete floor

Firstly a big thank you for the post to my other question re: timber or concrete.

I have had a damp and timber survey done independently and he thinks that there are probably 3 reasons for the ground floor timbers being damp. Firstly the void between the joist and what seems to be concrete underneath it is only a few centimetres so if the concrete is damp this may cause the timber to be also. Secondly the air bricks (cavity wall) may be blocked. Thirdly although the whole ground floor is timber, the kitchen at the back is concrete and damp. They think that there may be insufficient ventilation getting through the floor because the concrete is not providing a through route. The timber now has wood weevil although to stand on it feels completely solid with no bounce or bend. The DPC is in fine.
My main question is what can be done to provide a through draught for this and will it help if I put a damp proof membrane between concrete and joists to stop it rotting further?

2 Answers

Best Answer

Hi johnboyinsole,

Either fit more air bricks or make sure the one's you have aren't blocked for your timber floor. DPM on top of the concrete will help if the damp is rising through the concrete subfloor. It won't help much if there is a lack of ventilation, which is causing the problems condensation etc. Be best to treat the floor joists timbers to stop further rot.

Kitchen floor sounds like it needs a dpm of some kind or another.



Answered 3rd Jan 2012

Rebel Carpenter

Member since 24 Sep 2008

You need to add more air bricks.
Depending on outside ground level use telescopic vents.

Answered 3rd Jan 2012


Member since 29 Oct 2008

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