Roof insulation question

Hello,

I have 4" roof joists and 4" of insulation in my loft and I want to make it either 8" or 10" of insulation. Some of the loft is floor-boarded and I'd like to floor more for storage etc, do I lay the extra 4" of insulation in-between the joists and squeeze it in with the loft board or is it not possible to board over the extra thick insulation?

TIA,

Darren

Reply to
Darren Cooper
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Compressing the insulation will negate its effect. If you want to board over an area, start by laying a second layer of 4" joists at right angles to the exisitng ones and fill the gaps with the extra insulation. Then lay the boards on top.

Bob

Reply to
Bob Minchin

Darren

There is stiff high performing foam insulation board about 2" thick. Use this over the joists and have the chipboard over. The screws run through both. Have this in the parts of the loft where boarding is needed. The other parts, add Rockwool until 300 to 400mm deep.

Make sure all the holes into the loft are sealed. Pipes and wires. Fit an insulated loft hatch that is sealed.

Reply to
Doctor Drivel

Compressing the stuff will lose much of the extra insulation properties.

An easy way to add more without having to tit about making the joists deeper (or laying cross joists etc) is to lift the boards, lay a ridgid board insulation[1] onto the joists, then lay the boards back on top. Screw right through the insulation into the joists below to fix the boards in place.

[1] a foil backed PIR foam like celotex or one of the many cheaper equivilent makes - you won't need 4" of the stuff however since it insulates much better than rock/iso wool. If you wanted a cheaper alternative, then jablite would probably do as well - although you would need to take care to keep any cables away from it.
Reply to
John Rumm

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