Hey folks, I have a couple questions for your community. But first as this is my first post, and as is customary in other forums I am a member of, here is a brief description of who I am and my timber framing / woodworking experience. Or you can skip to the next paragraph for the meat of my question. I like to think I have a pretty good handle on the basics of timber framing and construction techniques. My biggest self design and construction using timber frame is an 8x12 wood shed using simple half lap and mortise and tenon joints. Generally speaking I have been woodworking small around the house projects for about fifteen years and every project is a learning experience. While I don't have formal construction education I studied engineering for a couple of years in university before I switched to geology as a major. Currently I am conceptualizing a new house for my family. Basement and main floor will be ICF (8" concrete) and conventional framing (for the most part) for the second story and roof. On the main level in the kitchen, dining and living areas we want a timber frame look. A friend of ours is a timber framer and we like the jointery and look of big timber. Unfortunately the new house construction will be on the opposite side of the country (Canada) and he won't be there to help us.

My TF question concerns two beams and second level floor joists. There are two 18' spans that I intend to cover with 8x12 beams. The ends will either be in the ICF structure or incorporated into the conventional framing. The total span for the joists will be about 22 and a half feet. One end of this span will end on an outer wall of the ICF the other on a beam as mentioned above with the second beam in the middle of the joist span leaving about 10'8" of floor area between beams. For joists I am thinking 5x8 but could go bigger if there is too much bending over the 128 inch span. As for joist spacing I was thinking somewhere between 24 and 30 inches. Once the concept is finished I will take it to an architectural draftsman to be drawn and inspected. I could post plans if that helps explain things.

Thanks