Insulating roof in an old house.

antoinolachtnai

I want to insulate my roof.

My house has a twin-peak roof. It was built around 1840. A year or two ago, I had to take down a ceiling due to water damage (leak in the roof which is now fixed).

Some of the floor of the attic is boarded. However, apart from that, there is no insulation.

The rafters are set at roughly 12" centres. I think they are around 2" x 5" (though not sure but I can check if it is critical).

It is going to be a big job to insulate, because all the boarding up there has to be pulled up. There is good access, but it's not a particularly pleasant space to work in. So I want to do the best job I can while I am at it.

What type of insulation should I put down, and what thickness should it be?

Should it be between the rafters or as a blanket across them?

If it comes above the level of the rafters, should i compact it down when I put the boarding back down, or should I try to raise the boarding with battens?

Antoin.

Viking House

antoinolachtnai wrote:

What type of insulation should I put down, and what thickness should it be?
Should it be between the rafters or as a blanket across them?
If it comes above the level of the rafters, should i compact it down when I put the boarding back down, or should I try to raise the boarding with battens?
Antoin.

Rockwool is better than glasswool because it is denser and holds onto heat longer.
Insulate between the rafters and then insulate over the rafters with a total minimum of 300mm.
Do not compact the insulation as this reduces the U-value and you should crossbatten if you want to put down some sheeting.