· What size studs should I use?
· Should I do it in two sections, one below the chair rail and one part above?
· Or should I cut slits in the lumber for the chair rail?
I used flat 2X4’s because I was planning on sheeting the walls with ¼” luan. I got lucky and found some sale priced knotty pine T&G that needed some care (cuts and sanding) . You could use 1X2’s, 2x2’s or flat 2x4’s.
I sat a 2x2” plate on top of the chair rail and screwed it from underneath with 1 1x4” drywall screws (or gold construction screws) through the holes that were already in the chair rail. You may need to put washers on your screws if you're not going to drill the holes yourself.
I then cut some 2X4 blocks that fit very
tight vertically between the floor and the underside of the chair rail and drove them in with a hammer. I put one 2 1x4” hex head self-tapper through them into the sheet metal. They drove in so tight the blocks probably didn’t even need that one screw. Drywall screws work fine for me...the difference is that drywall screws are black and some have a fine thread made for fastening material to metal studs. There are also black drywall screws with a coarser thread made for fastening to wooden studs. The gold construction screws also have the coarse thread.
You’re wall work and insulation already looks good, I doubt if you will have any troubles with the rest of the walls.
If you are using pine T&G and putting in a couple of partitions I used 1X2” Oxboard (waferboard) or 1x2” plywood and overlaid it with the pine T&G. I screwed the pine from the back thru the Oxboard with 3X4” gold construction screws. The other side will get Luan fastened with small wire nails.
Passenger side Refer cabinet under construction. I have overlaid the 1/2" plywood with knotty pine T&G but I don't have any photos of the overlay posted yet.