OT - under floor ventilation

[David]

Notice what seemed to be a strange thing on our deck out the back. Snow was clearing from between the gaps in the decking, and melting over the screw heads even though it was sub-zero.

What I think is happening. When the extension was built, ventilation channels from the suspended wooden floors (original) were installed in the solid floor to allow underfloor ventilation to avoid damp. The underfloor area is above freezing. Air is flowing under the house and warming a bit, then flowing out under the deck at the back. Sort of very minimal under deck heating.

Until I saw the snow and ice melting I had never considered that there would be any real heat loss through the under floor vents.

Then again you wouldn't want the under floor area to go sub-zero.

The most of the joists are insulated to keep the ground floor rooms warm. Perhaps I should revisit the amount of lagging on the underfloor pipework.

Cheers

Dave R

[PeterC]

Lagging the pipes is well worth the effort - much less trouble than trying to repair a pipe. Had this with a house - the front rads. were fed by pipes that ran inches from an air brick in the NE wall. Ventilation very necessary, couldn't get my 6' 4" ubder there, no easily kidnappable small children etc. but managed to slide insulation all the way along. It'll always be a bit warmer than freezing weather under there as heat comes up from the ground. I've seen water trickling from under a bank of snow in

-5C weather - the road was a mess! At -2C this morning the slabs on the path were free from the light snow as they still have a bit of heat under them (well, a lot but most isn't of use).