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.

No its not.

Its to prevent condensation on cold beams.

If they are vapour barriered, modest ventilation the works.



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.


Utter tosh. You neither understand how the insulation is applied, nor why.


Celotex is made and approved for exactly this scenario: roof joists with
eaves venting behind, and habitable space inside.


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


Absolete tosh.

That room air change ion a modern insulated house is controlled by
specific deliberate and known sized ventilation. Nit by random icy draughts.



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.

More complete rubbish.

If its permeable, the wind gets in and destroys the properties. You
don't go out in an icy wind with JUST a jumper on. You need a windproof
covering over it.


My advice to the OP is to disregard everything this idiot says. he
appears to have no clue about insulation, damp or heat loss whatsoever.