On Dec 20, 5:37*pm, Ronald Raygun
wrote:
Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.

I don't think that's a good idea. *The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well. *If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.

You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.

The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.

I think it's best not to insulate with anything non-permeable. *Use
underlay if you must, but with beautifully varnished floorboards, the
in-character thing is to have rugs, not wall-to-wall carpet. *With rugs
you don't want an underlay that's too thick, or you'll keep tripping over
the rug edges. *Worth a try is thin cardboard.

If you can identify any spots where the draught is excessive, caulking
the gaps with ordinary string may be effective.


The point of underfloor ventilation is to conduct away the damp that
evaporates from the earth below, so RH doesnt rise high enough to
cause rot. If you insulate between the josits with no VB, you'd be
right, condensation and rot could occur. But with insulation and VB
above all is well.


NT