I am adding a room into an existing garage. I drew in a foundation wall for the new end, the other end will sit on the existing foundation wall. How do I add joists and rim joist for the new room. I am new to Pro and any help would be appreciated. I'm also having trouble getting a new roof to sit on the wall on one end, when I frame in the roof, the one wall extends higher and the trusses dont sit on the other wall. Thanks for any help. Stay safe!