Wall Battens for garage/office conversion: Green treated rough sawn 47x50mm or standard CLS 38x63

[Yapstick]

Got the roof on (cold/fibreglass) and the new DPM'd and insulated concrete floor, on my garage to office conversion, and now looking to start battening up the walls. I'm just in a bit of a quandary trying to decide what to use for battens.

I plan on putting in 50mm rigid insulation and vapour barrier over that and the battens before attaching plasterboard.

I was initially going to use the CLS (63x38) but attach it length-wise as I reckoned the 38mm wouldn't be deep enough (insulation that thin would probably be a missed opportunity).

Then I wondered if I was missing a trick by not taking advantage of the rot resistant green treated stuff and it's apparently more suitable dimensions (47x50). Just wouldn't have the heft of the CLS... Any ideas/suggestions, much appreciated.

 

[oldbutnotdead]

50 x 50 nominal will work. You'll need more than 50mm insulation to keep building control happy- ideal would be 50 between battens, 50+mm fixed to battens then pb or whatever on top (reason for + - building regs changed this June, suspect the insulation requirements will have been increased).

EDIT If the wall is half brick or solid (no cavity) then Def use treated timber whatever size you go for

 

[^woody^]

There is very little if any difference in the cost of treated and untreated, so there is no reason not to use it where there is a risk of damp and rot.

Treated 2x1 or treated graded roof tile battens can be doubled up and are often cheaper and more commonly available than treated 2x2

Polythene up the wall first if its a solid wall

 

[Yapstick]

Thanks for your replies. The garage is a standalone unit. The front and one side wall are solid double-bricked, the other two are single bricked. Built in the 40s or 50s.

You'll need more than 50mm insulation to keep building control happy

I thought these 'ancillary building' types in Scotland (along as they're not 'dwellings') didn't really require that kind of stringency?

Polythene up the wall first if its a solid wall

I was going to use vapour barrier over the top of the insulation board and the battens, before putting on plasterboard. Won't it stop the walls from 'breathing' if I put it against the outer wall?


So, it looks like the treated stuff then. maybe I should try for 60mm though, to allow for deviations and extra mortar from the bricks (some of it looks like the farmer built it himself (structurally sound but a bit sloppy in places).

 

[^woody^]

I was going to use vapour barrier over the top of the insulation board and the battens, before putting on plasterboard. Won't it stop the walls from 'breathing' if I put it against the outer wall?

You need to stop damp getting in via the walls.

Walls breathe outwards not inwards

 

[oldbutnotdead]

I was assuming attached garage rather than an outbuilding and I'm not familiar with requirements North of the border. That being said, you'll be more comfortable and have lower heating bills if you go for more insulation at this stage (you get cold quickly sitting in a chair exercising your brain)