I'm going to be building a pergola-style patio cover. This will be attached to the house on one side, but the other side will have a beam, probably 6"x8"x14'. Rafters will be 4"x6"x11'. Posts will be 8" round. I'm wondering what the best wood to use is, that would result in the least amount of potential warping. It will probably be Ponderosa Pine or Douglas Fir. Green or dry? I might be able to get KD Doug-Fir locally but I haven't checked. I'd rather not use a glulam or LVL. Suggestions?