Hi, you hadn't specified what kind of wood that you'd be using, but here is my experience with wood cages.
I started out 11 years ago by getting 2 young adult males for free, then I bought 2 females the next year. I kept them in two large, display type cages that I made out of ply-wood, and had stained them to look as good as I could get. I used these for 8 years with no problems at all (not 1 vet trip). These were hard to heat, being that they were 4-5 ft tall, plus I wanted to get more boas. So I decided to make some new cages. they were 48x30x24. I made these out of plywood as well, but I had not stained them. In the next 3 years, I had 7 boas die, out of the blue, 2 of them being gravid, 3 were het for albino adults, 1 hypo, and 1 striped(about 70%). A friend, who also made cages from the same wood, had 2 of his 3 boas die. The vet (also a snake owner) didn't find any usual signs like resperatory infections, or mouth rot issues ... So I decided to start all over with new cages made out of melamime. So far Everything has been real good.
I've heard that pine, and fir, and cedar are very fragrant woods, and are not good for snakes. Also, that plywood is treated with phormaldihide.
Just for the sake of questions, I had lanolium on the floors so the wood wouldn't absorb their fecal fluids. I kept accurate temps for boas. Like I said everything went good for the first 8 years until I used the uncoated wood --- so keep that in mind when making your cage .