Insulation - dumb question?

[bloke_down_the_pub]

I’ve offered to insulate my sister in law’s loft. It’s a bungalow, with 100mm of insulation and she has electric only heating. The bills are crippling her, needless to say!

The top up rockwool insulation she has got, has a lightweight polythene covering on the actual insulation. Presumably this will make the job of rolling it out and positioning the stuff easier, quicker and less unpleasant. Question is, does the covering need to come off the insulation after positioning, or can it be left on? I was thinking: Maybe it could cause condensation if left on?

 

[flying haggis]

is the polythene perforated if yes I think it can be left covered

 

[Flynnwood]

What does the manufacturer say about it?

 

[bloke_down_the_pub]

The polythene is not perforated and there’s nothing on the outer packaging from what I saw of it. Thinking about it, Kingspan foam insulation is not vapour permeable either…

 

[baldkev]

It shouldnt hurt. If the plastic is adhered in any way, its probably meant to stay..... i believe current regs for that epc thing is 270mm of cozywrap...... obviously anything will help, the more the better. Watch out for light fittings.... if halogen or anything else that gets hot, you have to leave a gap around them. Ive seem terracotta pots over them in the past

 

[artie]

I phoned the local council a few years back, they sent a couple of guys out who did mine with 300mm foc.

Being 60+ has some advantages.