Usually I post about the things that have gone right, but we are on a learning curve, and things often don’t work out first time around. The floor in the new build is one such case. After much deliberating, and mainly due to budget constraints, I put in a suspended floor, with a membrane to hold insulation between the joists, and to keep draughts out. The space beneath the floor has to be ventilated in order to keep the air moving, otherwise still, cold air will encourage rot in the joists.

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Unfortunately I didn’t bank on just how much air would find its way through all that membrane and insulation, and up through the floor. Quite a lot as it happens, which rendered all the strawbale insulation more or less meaningless, and resulted in constantly cold toes if there was any wind at all.

The solution? First to block up all the underfloor vents, which would normally be a no-no. Secondly to fill the underfloor space with recycled foamed glass insulation (in this case Glapor). Made from recycled glass that has been melted and had air blown through it, the material is completely inert, contains only recycled glass, and does not wick moisture through capilliary action. It is also a great insulant. So we should avoid the issue of a large cold body of air under the floor, gain an additional 250mm of insulation to add to the 150mm of sheeps wool between the joists. 400mm should keep things pretty toasty.

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The downside was having to lift the floor, but it was a good opportunity to check for moisture underneath (it was completely dry) and top up the between joist insulation.

The result? Well, this evening it is very windy outside, and now that the mass heater has been lit, the room is warm, there is no hint of draughts from the floor, and finally the place feels like it is behaving as I always hoped it would.

Like many of the products we’ve used, the Glapor came from Ty Mawr, who we can’t recommend highly enough.

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