Willow
Recently I was at a house addition raising. The foundation and floor joist with sub floor were already in place similar to what you have described.
“Trying to design a timber frame to fit over a walk-out basement. Basement is 28x44, 8" block walls, concrete sub floor. Floor joists & sub flooring for first floor is already in place. Any suggestions?”
What this company did to erect the frame on this existing situation was to cut away the plywood floor the spots where the posts were going to be. Then we notched the posts to fit each spot so that the posts actually set down directly onto the foundation capping pressure treated 2x material. This, I was told, was to give good support to the frame.
In your case things maybe different. Sometimes foundations need to be built ‘for’ a timber frame building. That is bigger at the points where the posts are sitting. This is due to the concentration of the weight of the building in these areas. So be careful and have someone who know about designing and/or engineering check your plans. Or have a planning discussion with your building inspector. He should be able to tell you if your foundation is adequate to support a timber frame. You might have to add concrete into the foundation blocks at the post location or something like that. Good luck and I hope this has helped. Jim
