Underfloor insulation

I think I read that heat loss via floors is about 10%. I insulated the underneath of my timber floor after I exposed the timbers, as I thought it might get a bit cold. Nasty business doing it with rockwool though, it drops in your face and down your nack, unless yo lift all the floorboards. You would be better off using some kind of polystyrene or cut slab rockwool.

As far as I can see the best return on money, far better than double glazing, is to get your cavity walls insulated.

Andy.

In article , mogga writes

It's because it's a complete faff to do and it would take a tradesman ages* so wouldn't be cost effective. I've done it myself so know what a PITA it is but now that is done I am very happy with it :-).

(*) Compare with the time it would take to roll out some fibreglass or rockwool in the loft.

| I've been reading up on what's been said previously about suspended | floors insulation and was curious about whether anyone did it - so I | rang a few companys and they all said no. One company told me it | wasn't neccessary as heat rises. | So why do the pictures of heat loss show 15% heatloss thorugh floors? | And why does no one do it?

Because it is hard dirty work. Maybe ?5-10? times the trouble of doing a loft, for probably less return.

I did it and it was *very* hard work, in the crawl space below the suspended floor. I got glass fibre mat as thick as the joists and started putting it up on the floor boards with a staple gun which did not work well. I then held it in place with clout nails in the joists and polypropylene string across/under the mat. Finally belted the clout nails in.

The advantage is mainly in warm floors.

We had the "opportunity" about 18 yrs ago to do this while digging out beneath the floor, creating a cavity. Yes, tradesman prices make this unrealistic as a postfix; but given the chance do it for yourself! We are very, very pleased with the warmth that reaches down to floor level. We strung nylon net between joists, then laid in rockwool. Re-visiting at rare intervals shows it is all still in place. Phil

In article , OLDTOWNGUY writes

Images appear of guided tours :-)

I've seen it done your way at build time, much simpler.

I've just helped a pal do this on a new build (yesterday). 25m2 of 100mm insulation supported below the ground floor by a combination of supporting walls, nails and twine. We've got to do it twice more as well - between ground and first floor and between first floor and loft.

The reason nobody does it is that it's a complete PITA.

We had no choice - it was specified as part of the build (although how the BCO was going to check we'd done it after the floor is down is anybodys guess).

I put 1", 25mm thick Styrofoam on the existing floor then put down a new floor

What the hell's styrofoam? Do you mean expanded polystyrene?

| kitchenman wrote: | > I put 1", 25mm thick Styrofoam on the existing floor | | What the hell's styrofoam? Do you mean expanded polystyrene?

American trade name for expanded polystyrene

because that is pretty much what it is.

You need UF ventilation with wooden suspended and that makes it a LOT more than that. Especially with shriunken boards...

Lift em up, shove celotex between joists, tape over the joists, and re-board.