Hi Chris, we are building a motorhome (9m bus) We have put Batts in the inside walls and covered them with 3mm customewood. Now we are noticing the customwood have several little "waves" appearing, mostly near the top of the sheets of wood, near the windows. A friend has suggested that we should have drilled holes in the wood to let the Batts "breath" We are going to cover the walls with Autex carpet.
Would this be the reason or just "warping" ?
Also, what thickness of wood should we use to line the shower base,attached to the sheets of seratone?
Thanks for your help,
Josie

Just a comment and probably too late to be helpful. Never use customwood in an area that might get damp (ie a camper). Hardboard or ply would be better. I used 10mm customwood to line walls in an old house once. Thought it would be cheaper than jib. It went wavy in a short while. Thin customwood acts a bit like cardboard. I sujest you get some good advice before you proceed further.
Sorry I don't have a fix for you.

I used leather grained fiberglass sheet 2mm bends easy and can be got from custom rv in ramarama