Attic insulation for walkable area

grahamor

Hi,

I have recently insulated 3/4's of my 40m² attic with Earthwool 150mm insulation

The remaining area is covered with chipboard for storage etc and there is no insulation underneath.

Seems like i should try and insulate this area too as it's quite a large area.

Does anyone have advice on how best to insulate under the chipboards ? i could obviously pull them up and stuff the Earthwool underneath but reckon there might be a better way.

Thanks for any info.

Gumbo

pull the boards up.
put in some insulation that is less thick than the joists and allows air circulation.
then put the boards back down.

you could add battens to the top of the joists to get more insulation in before putting the boards back down.

Don't put the boards back down by squashing the insulation, you are destroying its thermal properties by doing so.

grahamor

Thanks. Good point about not squashing down the insulation under the boards.

BryanF

Lift attic flooring, lay pir insulation boards on top of joist and relay ply(?) with suitable screws

BarneyMc

BryanF wrote: »

Lift attic flooring, lay pir insulation boards on top of joist and relay ply(?) with suitable screws

Can the PIR be laid side by side tight to each other or should they be left a small gap for possible expansion?

Dudda

BarneyMc wrote: »

Can the PIR be laid side by side tight to each other or should they be left a small gap for possible expansion?

Lay tight with no gaps and fill any gaps with expanding insulation foam. Otherwise the heat will escape through the gaps which defeats the purpose of the insulation.

corkgsxr

Use kingspan. Dear but much better insulation value than earthwool

BarneyMc

Dudda wrote: »

Lay tight with no gaps and fill any gaps with expanding insulation foam. Otherwise the heat will escape through the gaps which defeats the purpose of the insulation.

Will the double foil sided slabs prevent moisture rising into the attic space and cause condensation? Also if the slabs are laid tight then are they liable to buckle during warm weather?

BarneyMc

Anyone?

BryanF

BarneyMc wrote: »

Will the double foil sided slabs prevent moisture rising into the attic space and cause condensation? Also if the slabs are laid tight then are they liable to buckle during warm weather?

Provide Vapour barrier taped and sealed on warm side. Pir slabs don't expand

BarneyMc

BryanF wrote: »

Provide Vapour barrier taped and sealed on warm side. Pir slabs don't expand

My airtight membrane is tacked to the underside of the joists and below that the non-insulated plasterboard. I assume this satisfies?

BarneyMc

Hope to get my attic finished soon. Will ply (or similar boards) expand and if so how much of a gap should be left between the ply boards?

BryanF

No real need, how are you fixing? Can you glue boards to joists?

BarneyMc

BryanF wrote: »

No real need, how are you fixing? Can you glue boards to joists?

Placing PIR boards on joists first, then play on top. Any need to fix the ply boards if they are laid tight enough together?

BryanF

BarneyMc wrote: »

Placing PIR boards on joists first, then play on top. Any need to fix the ply boards if they are laid tight enough together?

Yeah I would.

BarneyMc

BryanF wrote: »

Yeah I would.

So nail down through the ply and PIR and into the joists?

Outkast_IRE

Any issue with just using loft legs to raise the chipboard and insulate as normal under it.

This always seems one of the more practicle ways to sort storage.

BryanF

Outkast_IRE wrote: »

Any issue with just using loft legs to raise the chipboard and insulate as normal under it.

This always seems one of the more practicle ways to sort storage.

Yep

BarneyMc

Outkast_IRE wrote: »

Any issue with just using loft legs to raise the chipboard and insulate as normal under it.

This always seems one of the more practicle ways to sort storage.

For me I already have the PIR boards in the attic. Also it will help with head space with the lower floor.