Is it safe to cover paper-backed insulation with wood, probably pallet wood? This is for a small mudroom. Thanks!
Safe yes. Recommended probably not.
Last time I looked, except where the wall is a fire barrier, the building codes site smoke generation of the paper coating that has to be covered. I believe plywood of a certain thickness satisfies the code so tightly fitted planks may also.
Covering a room with pallet wood sounds pretty nasty.
My memory could be wrong with what is required to cover the insulation.
1 - Yes, there are likely code issues to not have drywall on every interior surface of the framing.
2 - Yes, you want drywall first, regardless of codes, to eliminate the odor of the insulation/paper backing and drafts, both through penetrations to the exterior and by convection.
3 - Insulation works better in a captive environment, as it is the trapped air within it that does the insulating. Drywall gives you that, plus many other benefits.
4 - Drywall is going to look better and be easier to keep clean when painted with a gloss/semi-gloss paint. It's also going to help keep odors down because odors won't have all the nooks and crannies that pallet wood does.
I was wondering if there was a specific reason you wanted to cover the walls with pallet wood.
Was it because it was basically free wood?
Like stated above, it's a poor choice.
Code requires 1/2" drywall or equivalent regarding interior home fire protection. 1/4" or 3/8" drywall underneath the wood may be acceptable as wood, while not as fireproof as drywall, does have 'char time' that adds to fire resistance. You need to check with your local codes inspector to find out what you'll need to do here. Just don't put it directly over insulation as you describe for the reasons already given.
Rough-sawn wood can look great in the right places. I have friends who made use of free spruce shipping crate wood in their mountain home. The downside is that the surface may be too abrasive if you brush an arm or leg across it, cleaning it is nearly impossible due to the roughness, and it loses most of it's visual appeal when painted. Splinters may also be an issue according to what you've got. So once it gets dirty all you can do is replace it or cover it, and in most homes that makes it less suitable for use than other materials. Most of this kind of wood is also not cut to similar exact widths or thickness, so some re-sawing or back-planing may be necessary. You can run across embedded metal when cutting; not good for your blades. Also this will usually be a very poor grade of wood with many defects. But if you've got enough of it to sort through, you can probably find enough usable lumber to do your projects and free is always the best price.
There is one very important thing to watch out for when using pallet or crating wood- laws require that wood used for these purposes coming into the US be treated to be insect free, which is usually done through batch-fumigation using chemicals which are very toxic and not allowed inside any enclosed habitable environment. IIRC these are marked with a blue or purple paint stripe but I might be wrong on that. As long as the wood is domestic you're probably OK.
If you want the look and are willing to deal with the potential issues, I say go for it. Your project will be unique and if done well, one you can be proud of.
I should know better, but the code does require a minimum of 3/8" gypsum board under wood paneling. Plaster can also be used. Thicknesses are called out for specific locations and stud spacings. Looking for the embarrassed emoji.
Ditto the comment that pallets may be treated with any number of chemicals these days as many come from the Far East.