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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> Loft conversion insulation https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1460400877 Message started by Stu1975 on Apr 11^th, 2016, 7:54pm

Title: Loft conversion insulation
Post by Stu1975 on Apr 11^th, 2016, 7:54pm

Hi

The builders have used kingspan boards between the roof joists - do you also recommend using typical wool type insulation or will the kingspan be ok? The space up there isn't massive.

Thanks :-)

Title: Re: Loft conversion insulation
Post by thescruff on Apr 11^th, 2016, 9:26pm

How thick and have they left an air gap behind it

Title: Re: Loft conversion insulation
Post by Stu1975 on Apr 11^th, 2016, 11:13pm

It's 100mm - not sure about the gap behind it.

Title: Re: Loft conversion insulation
Post by thescruff on Apr 11^th, 2016, 11:47pm

100mm Kingspam is as good as it gets unless you go even thicker.

What you should have is an air gap behind it, Tape all the joints, them a vapour barrier before the final finish Plasterboard/whatever. Can you remember the depth of the rafters

Title: Re: Loft conversion insulation
Post by Stu1975 on Apr 12^th, 2016, 7:26am

Size of the rafters - no idea I am afraid :-?
I've heard kingspan is good stuff, my only worry is that the loft area will be warm and the rooms will be cold and there is nothing to stop the heat from going into the loft as there is no insulation directly onto the celing.

Title: Re: Loft conversion insulation
Post by thescruff on Apr 12^th, 2016, 8:00am

What is the loft being converted for ? if it's not being used for other than storage, than I agree insulate the floor.

A friend just converted his loft to a room and used kingspam in the rafters and wool in the floor

Title: Re: Loft conversion insulation
Post by Stu1975 on Apr 12^th, 2016, 8:46am

The old loft space now contains a 2 bedroom and a bathroom (Dorma extension) the there is now a new little loft space above. I wouldn't even use it for storage to be honest. I didn't want to over insulate in case is causes sweating. Something the builder mentioned. He's said there is no requirement for wool up there as the kingspan is fine.