Damp Proofing Question

Ventilation to subfloor

The suspended timber floor in the living room seems to have acquired a damp problem. I noticed recently that the joists are damp where they meet the walls. They are damp all along both walls (internal walls, one is party wall to neighbour and other is adjoining hall and kitchen, which have a solid floor.)
I had a conservatory fitted 2 years ago (with concrete floor), and to continue the original ventilation 2, 65mm pipes have been used to duct air to the subfloor. Unfortunately it seems as though there is some blockage to the vents from inside by way of the damp membrane or insulation product, which the conservatory company have said they will rectify.
I am wondering if this problem alone could have caused my joists to be wet?
I have read that building control recommend at least a 100mm pipe per vent and although within permitted build and not requiring building regs, should they have used 100mm pipe anyway?
I was considering replacing the 2 air vents at the front of the house as the old ones are a little delapidated although are bringing in air quite well, would adding a third vent to the front of the property serve any purpose? (would this compensate for reduced ventilation to the rear?)
Thank you in advance for any answers.

1 Answer

Best Answer

Ventilation to your original suspended floor is essential to prevent further damage and issues such as rot. The conservatory company should have laid 100mm rectangular / round ducting through the new solid concrete base which should be connected to air bricks / sleeves in the new external brickwork and clearly pass through the original outside wall and into the floor void underneath the living room. The new air bricks / ducts should be spaced no more than 1800mm centre to centre and no further than 450mm from a corner. It sounds like both the size and quantity of what has been fitted is insufficient.

Answered 13th Oct 2013

Brayfield Construction

Member since 1 Oct 2013

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