how to insulate behind wooden shiplap cladding?

[happyolly]

Hi,
We're building a lean-to garage from Thermalite block, I forget the exact brand but it's the light stuff you can cut with a hand saw.

The exterior will be battened with 25mm deep battens and clad with 12mm shiplap wood.

What would you suggest we use for insulation between the board and wall please and what type of membrane (if any) is required and where should it sit?

Thanks

 

[pinenot]

You use a membrane between any two differing materials where the possibility of condensation could form at the point of change. In other words you put a moisture control layer between the "presumed" warm interior and the colder external, which in your case would be between the breeze-block and the timber cladding.
It's important to know which blocks are being used to advise properly, but assuming they are lightweight aerated concrete blocks, these have quite good thermal/insulating properties already...pinenot

 

[happyolly]

Hi there, sorry for the delay in replying.
Xella, Ytong the blocks we're using (7n/m I think).
I can try and find out the exact model but it doesn't seem to be written on the plastic pallet wrapper.

The battons the shiplap will be nailed to are 25mm thick.
Is it worth using insulation and any recommendations for which type? Cost is a strong consideration.

I guess the moisture barrier would go between the cladding and the insulation?

Thanks

 

[AronSearle]

You don't insulate that 25mm cavity, you leave it for drainage and ventilation of the ship lap cladding.