Advice Please! Insulating a garden room! Help!

[putnammj]

Hi All,

I am new to the forum but have ready many posts and am a little confused! I am looking to insulate a timber garden log cabin 16ft x 10ft (walls and ceiling for all year use as a home office). The cladding is relatively thin at around 25mm. In the interior the battoning is only 44mm deep.

My plan:

- Extend interior vertical battons depth by 63mm to create 107mm recess (existing 44mm batton + 63mm studwork) and paint with preservative
- Fit 80mm celotex flush to batton leaving 27mm air gap between celotex and exterior wood cladding
-Staple a thick polythene sheet after celotex to stop moisture passing through
-Add plasterboard

So would look like this on side profile:
Outside wall/23mm air gap/80mm celotex/polythene sheet/plasterboard

Guys please please let me know if you think this would be sufficient and any advice would be much appreciated! For instance I have heard discussions of breathable membranes but dont know what this is or where i would put it! Would polythene sheeting after the celotex and before the plasterboard be sufficient etc?

Please help advice needed!

 

[KennethvanPelt]

I too am looking to insulate and waterproof a garden office I have built. I have the basic frame up with the roof boards in place. I can see daylight between the roof and at the corners where the 'logs' cross each other. I was planning to mastic these gaps up and then put a second wall in like putnammj. This was my thinking.

Walls (in layer order)
Breathable membrane.
Then batons at 600mm intervals
Insulation
Plasterboard

Roof (outside)
Breathable membrane
Felt

Roof (inside)
Aluminium foil
Insulation
Hardboard (or similar) nailed to beams that support the roof.

Can anyone advise if this is roughly the right way to go?