Expert: Dave Johnson - 7/23/2008

Question
Dave, I have a 20'X36' cottage. I want to add 8' to both sides, therefore making it 36'X36' simple gable. All of the roof stucture will be replaced with new rafters; trusses are out of the question due to area to lift them. Can I leave the exsisting ceiling joist in place and run new ceiling joist along side of them, the whole length, 18' (scabbing) from the center of the house to the new outside load bearing walls, eight feet farther out, without putting a beam where the old outside load bearing walls were at?  The old ceiling joist will be nailed to the new ceiling joist side by side, and supporting nothing but remaining ceiling.

Answer
Hi Johnny,
No, the joists will sag at that span. But, if when you frame the new ceiling as you just said, and put up the new rafters as well, you will be able to make trusses right in place.
Look at a picture of a simple truss, and use it as a guide.
Your webbing should be 2"x4" lapped onto the joists and rafters and well nailed. The "W" you will see on a rafter pattern goes like this: the longest web goes from next to the ridge to a point 1/3
the distance of the total joist (12') the next one goes from there to a  point 1/2 the distance of rafter length.Make sure all rafters and joists are straight and don't stand on them when nailing/screwing...(they will bend under your weight and look awful)
Pull out all walls to be removed AFTER making your trusses.
Best of luck,

Dave