Insulating walls of timber built garage

[dobson156]

I have a timber garage. The construction is 2.5m timber panels built from 3x2s bolted together. Each panel is clad in vertically aligned T&G.which as been creosoted on the exterior. The building has a pitched roof with corregated steel roofing sheets laid onto the roof timbers.

I'd like to insulate the walls and roof to make the space more habitable but more importantly, to reduce the amount of condensation that forms on the steels roof when the temperature drops quickly.

I'm confident when it comes to insulating the roof I can just do a conventional cold roof design leaving a 2-3" gap between the top of the insulation and the bottom of the panels with vapour barrier and ventilation.

What I am not so sure about is what the best way is to insulate the walls of the garage. Can I just apply the exact same logic as above, leaving an air gap? Is the air gap on the walls even necessary? If I do leave an air gap then does it require ventilating and how best to do that?

Thanks in advance.

 

[freddiemercurystwin]

Please say you fitted a breather membrane + vertical counter battens + horizontal battens before you fitted the cladding?

 

[dobson156]

I didn't build the garage! I am just using it now and need it to be warmer and dryer.


There is no membrane of any sort in the current construction. From the inside you see the 2.5x2.5 panels formed by the 3x2s and you can see the back of the TG's which currently forms the interior wall.

I'll take a photo and post it on here to show what I mean.

 

[dobson156]

This diagram show how a cold roof can be created by insulation between joists in a roof.

Can this just not be replicated on to the walls? Of course the difficult bit would be providing necessary ventilation. Not that the T&G is removely air tight anyway!

I really don't need that much insulation.

In my case I'd use some sort of rigid board insulation, OSB and still researching what'd be the best vapour barrier.