I have a small cabin. Last year, we installed new redwood siding. Basically redwood planks that run vertically. The planks are all now splitting really badly. Probably 3/4 of them have huge splits, and at the rate we are going I am sure it is a matter of time until the rest them split too. The splits run vertically, sometimes all the way from top to bottom. The contractor who installed the siding is experienced, and done a lot of good work for me in the past. But I am wondering whether he did something wrong? The only alternative explanation I can think of is that we just got a bad lot of wood, perhaps still green? (And yes, there is possibility moisture is getting behind the wall. I don't see any obvious sign of this, though perhaps I don't know what to look for?) Other questions: what do I do now? Can this be patched/caulked, or do we have to re-do all the siding?