Insulating attic and cavity wall

adam2484

Hello folks, a very simple query I suspect. 2 issues.

I plan on replacing the insulation in my attic. Essentially I have wool in between rafters at the moment - about 100mm installed when the house was built 15 years ago. The wool insulation has been ruffled about as we dealt with a rat problem that's now been sorted.

My rafters are about 7cm and my plan is..

Clear out old insulation. Raise the rafters by 3cm and install kingspan insulation boards 100mm. I know this will cost a fortune but Is something I'm prepared to do.

2nd issue is cavity wall insulation. We have bricks with polystyrene bound to them. There's is also an air cavity in the wall wall and I'd like that filling up with ecobeads or something like that.

Concerns - condensation in the attic and damp in the walls.

Does this sound clever and doable? Any suggestions welcome. I'll update as I do the various bits.

Also can the rats if they ever retuned chew through kingspan

rogerblack

Rats laugh at kingspan.
They chew through floorboards.
If the attic is ventilated, and if there isn't a vapour barrier on the top of the kingspan - don't seal the floor - it should be OK.

You do know you will probably need various forms of building control approval?
Ventilation in the walls will be significantly reduced by ecobeads.

adam2484

Building control...really? Lol

Does ventilation really matter?I don't have damp just don't it to cause damp.

zeupater

Hi

You'll do the same job much cheaper by tidying up the current insulation and laying new rolls over the top ... doing what you describe doesn't address thermal bridging through the wood and will just add unnecessary cost.

You can currently get hold of 170mm or 200mm rolls from the DIY sheds for aroung £3/roll (~5+sqm), picking some up tonight you could be benefiting from tomorrow .....

HTH
Z