I've read much about the respective pros & cons of green vs. dry timber design/layout/construction. It seems that the main reason to use dried timbers is stability and the 2 main reasons not to use dried timbers is cost (time and money) and workability. I have questions regarding both cost and workability. There seems to be little discussion of Solar Kilns. Solar kilns are realitively cheap to construct and allow for a controlled environment to dry that minimizes checking and twisting by allowing the wood to "rest" at night. The process takes longer than regular kiln dry but essentially requires only the sun (plus minamal needs for fans etc.)
Q1: From what I know, Solar kilns aren't usually used to dry post and beams the size typically found in timberframing but if done slowly enough why couldn't it be done?

Q2: Regarding workability (and not considering other factors such as strength, weight, straightness, stability, regional availability, etc.) Would using dried softer woods overcome the problems that hardwoods like oak present when dry?

Very few timberframes are built using kiln dried timbers. I think your explanation for this is correct --- cost. A small number of framers have their own kilns and as a consequence must rely on others to do the drying. Kiln operators realize more profit from a kiln full of furniture grade lumber than from one full of 10k bdft. of lower grade timberframe timbers. This equation is being altered somewhat by the emergence of RF kilns. Until recently, RF kilns have had a bad reputation for blowing up wood with uneven drying. As a result of newer technologies, some very good results are now being obtained with this method.

Regarding the hardwood vs. softwood question:
The issue is just the appearance and size of the checking. Kiln drying cannot prevent checking because it is caused by the difference between radial and tangential drying coefficients in wood. Species with a smaller difference between these two number will perform better.

We have recently run some RF dried timbers thru our shop, some observations. Big, long timbers did not dry well - they twisted and we could not use several. It is brittle and hard and tough to process. Small stock performed very well. Next time I will order small stuff dried and large green.
Solar kilns are great if you got the time to wait for them. Timbers would need to stay in there for a year to do it a lot of good - any time at all would help, but to get into the teen's MC would take a long time. We have good luck just letting things dry in the yard for as long as possible - even a couple/few months helps.
Most clients want it now and cheap - this is major reason little wood is dried.

Thanks Randy and Brian for replying. Your anwers helped. From your responses I'm not sure if your familiar with solar kilns. If not check out this article: www.woodweb.com/backart/wengert/solarkiln I realize that drying timbers for a profesional shop may take too long but if doing it for my own project and time wasn't as important, it would be cheaper than RF and if done slowly and carefully enough the checks would be minimal. I personally don't mind checks as long as they dont affect the structural integrity of the timber, which I'm told they usually don't. I even think some checking adds character. The reason I'm interested in solar kiln drying is not to prevent checking or even so much for what little strength factor there may be but for the stability/predictability of the wood. I know that green building works great but if the only reasons not to use seasoned wood is cost and time and if a solar kiln overcomes those problems it seems that it could be almost as good as using salvaged timbers only more renewable.

Thanks again
Gerald (dharmabum)