I currently have a detached one car garage that I want to convert to a an art studio for my wife. There are currently horizontal members sitting on top of the bearing walls running from one bearing wall to another ( in one direction only). The problem with these supports is that that they sit too low and when I eventually Sheetrock they will make the ceiling height too low. Is there a way to eliminate these and replace by shoring up the existing roof. Or is there a way to move them off the bearing walls and onto the rafters in an effort to get more ceiling height?
r
Replies
well, I'll be the first - "consult an engineer"
yes, there is a way - the horizontal members (joist) keep the roof from spreading -
a couple of suggestions - you might be able to remove the joist and create a 'scissor truss' system that would give you a vaulted ceiling to sheet rock -
or you could create a structural ridge - probably a bigger deal -
could you insulate/finish the underside of the rafters and leave the joist in place as they are?
If I understand you correctly, those are the ceiling joists that are also functioning as rafter ties to keep the walls from spreading apart from the thrust of the roof load. To function thus and hold the roof up, they must be in the lower third of the rafter space, so it might be possible in many circumstances to replace them at that higher elevation.
To remove them entirely and create a cathedral type ceiling, you would need a structural ridge
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The other responses are good. Piffen points out the thoughts I had.
If you could post a picture of your situation you may get better and more detailed information.
October 17th, 2009
Jeremy and Lisa
Was there ever any doubt?
As Piffin has said, those rafter ties resist roof out-thrust. They become far more critical on a low-pitch roof.
Garages are notorious for sagging and spreading roofs and inadequate door headers.
If you're going to raise them up, install new ties and then remove the existing ones or you're likely to cause irreversible spreading. And be certain to use wide enough members (with angled ends to match the roofline) to get good nailing into the rafters (at least four 10d common nails at each end) because all the thrust load will be on the shear resistance of the nails.
What is the roof pitch and how wide is the garage from eave to eave? Will the rafter ties span the entire distance or is there a center beam? If center beam, then be sure to splice the ties together where they meet to create continuity.
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