Question re attic insulation

pocketse

Hi

I'm in the process of buying a house at the moment. Got my structural survey last week and there seems to have been a problem with the way the attic insulation has been installed. There are insulation boards in between the rafters right up to the felt. Because of this there has been a build up of condensation on the external part of the rafter and if left untreated I was told it could become a major problem. There should have been a 50 mm gap between the felt and insulation for aircirculation. Engineer suggested that I replace with a thinner insulation or relay the insulation between the floor joists.

My question is : would it be ok if I hung a barrier rail around the rafters extending the depth of the rafters by 50 mm and then pulled the insulation out to rest on it. This would give the required 50 mm between the roof and insulation and provide circulation.

Any reason why this might be a bad idea?

Thanks in advance

Pocketse

SC024

basically what you want to do is build the bottom of the rafters down by 50mm to allow you to drop the insulation down so its 50mm away from the underside of the felt?

pocketse

Kind of. I'm not talking of extending every single rafter by 50mm. What i imagine doing is running a 2 x 4 perpendicular to the rafters around the whole roof. Perhaps one near the top and one nearer the bottom. I might only attach it to every 5/6th rafter using a small piece of wood which would give me the extra 50mm. Ill try to do a diagram of what i mean as I'm not explaining myself very well.

NIMAN

Can you not just pull the insualtion towards you by 50mm?
Ok so it won't sit flush with the rafters any more, but surely that wouldn't be a big issue?

pocketse

NIMAN wrote: »

Can you not just pull the insualtion towards you by 50mm?
Ok so it won't sit flush with the rafters any more, but surely that wouldn't be a big issue?

Yep that's basically what I extend doing. The only reason I'm putting in the barrier is to give the insulation something to sit against so it doesn't fall out and down. But in essence all I really want to do is pull the insulation out 50mm. There's no obvious reason why I should do this?

Rabbo

It shouldn't need a barrier, the insulation should be snug enough to stay in place by friction. If there are gaps, use a little spray foam insulation