An architects point of view
Hi Robert,
Here is my take on your siding problem. Ten years ago, when I built my house, I used cypress vertical board and batten siding. Here is the system I came up with and has worked well so far...
1. Use standard 2x4 stud framing for the wall framing. If you use a 2x3, you will have to do a lot of ripping on the table saw. The 2x4 framing should be 16" on center.
2. Run horizontal 2x4 standards or nailers vertically between the 2x4 studs at 24" on center. These are what you will nail the vertical board siding to. If you plan to insulate the walls, you will have to cut the insulation into 24" pieces to go between the wall nailers.
3. Use 1/2" plywood sheathing or oriented strand board sheathing. It is more commonly used instead of 3/8" plywood.
4. Use base flashing at the base of the wall. Base flashing is a black plastic poly 18-24" wide sold at most building supply stores. Run it horizontally overlaping the slab around the perimeter of the structure.
5. Overlap over the base flashing No. 15 or No. 30 felt building paper. I like it better than house wrap or Tyvek because it weeps water better and allows the wall system to breath better. Overlap the felt building paper a minimum of 3" with each course. The felt should overlap the lower piece so as to shed water like shingles do on a roof. I used plastic button tab nails to fasten the felt.
6. I used 5/4" x 12" band sawn cypress for my vertical siding boards. I purchased mine from a lumber mill in south Louisiana. If you can find old growth heart cypress, it will last for hundreds of years, but it isn't easy on your wallet, and could be very hard to find. You could use most any wood. When you nail the vertical siding boards, nail them into the wall standards or nailers using a stainless steel ring shank nail or stainless steel screws. The ring shank nails won't back out with wood movement. Leave about 1/2" space between the siding boards for expansion and contraction. I used a vertical batten 5/4" x 2". The vertical batten covers the 1/2" space between the vertical siding boards. Do not nail the battens to the siding boards!!! Nail the battens in the 1/2" gap between the boards. Remember you are working with wood which moves, and the wood siding components need to move with respect to each other
My cypress siding is going strong after 10 years and still looks great.
Good Luck.
Eric Commarato, AIA