Aredwood:

 

I want to insulate my house. But it has Skillion roofs throughout. So no ceiling space. It was built with 150mm rafters, so I could insulate it with R3.2 batts. But would have to either lower the ceilings or raise the roof to get more than R3.2 in the roof. But would going to R4 or R5 actually make much difference?

 

House is 2 storey on concrete slab, So can't do any underfloor insulation. And currently has no insulation anywhere. Built in 1969. In Auckland so not super cold.

 

Mainly asking as I also want to replace the windows with double glazed units. So a case of spending alot more on insulating the roof, Vs spending less on the roof. And instead saving up for double glazing. Or would insulating the walls be better than getting double glazing?

 

I am in the same position and hope to insulate my skillion roof this summer. One thing i like to tell myself is that we some times suffer from short termism. A well insulated house is the gift that goes on rewarding the owner year after year. The building code is a minimum although in NZ we mostly aim for that point according to what you hear tradies say.

Ideally to answer your question, you obtain information about your existing house and put it into a heating loss calculator to determine the effect of upgrading various building features.

Personally, i have old pinex ceilings that are as saggy as well cooked cabbage and they're gonna go, no matter what efficiency gains might bring.

Have you got windows facing South?

If you can lower your ceiling to max out your insulation, have a look at the rails and clips system offered by your favourite plasterboard manufacturer. They add an element of decoupling so would increase noise damping as well as thermal decoupling. You might only need an extra 25 mm on top of your 150mm rafters.

We think about insulation at this time of year but it works in summer too ! Now there's a happy thought.