I am considering an addition with a gable roof perpendicular to an existing gable roof with an 8/12 pitch. This existing roof is framed with 2″X 6″ rafters with only a 1″X 8″ ridge board and 2″X 6″ collar ties two thirds of the way down the rafters. I would like to move the collar ties up closer to the peak so I can open the ceiling for the old and the new. I am concerned about snow load here in New Hampshire and adding the additional weight of the new ridge beam (double 2″ X 10″) for the new addition onto the old roof. Can the existing roof be reinforced by doing the following:
1. Remove the shingles
2. Glue and screw 2″ X 4″s on edge running from the eave to the peak on top the existing rafters and sheathing
3. Install new sheathing on the 2″ X 4″ runners (after adding R13 unfaced insulation)
I am trying top avoid removing the entire roof since the inside is finished with aged V groove knotty pine.
Any suggestions?
Replies
How are you going to *NOT* mess up the ceiling if you're raising the ceiling height?
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Moving the collar tie up completely changes the forces in the rafters.
What works and what doesn't depends on a lot of thnigs, like the width of the roof, the pitch, lumber grades and species, your loading requirements, and your local codes.
I try to avoid the "hire an engineer" line, butI think you need to have someone evaluate the roof before you do anything this serious.
Thanks for your quick reply, I think you're right about hiring an engineer. I guess I was hoping for a "magic bullet" response.
If you post some more info (Like the stuff I mentioned) you might get some suggestions.
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The new ridge should be diagonally braced, keeping it from sliding into the existing roof or its wrong. You should brace on the diagonal at the new gable and to the strongback span splitters tieing the new ceiling joist together in the new attic. The new 2x10 ridge will also be bearing posted directly to the foundation or a beam that will disperse the weight to a new foundation location. Terribly time consuming and not good for the knuckles but I have sistered existing rafters to new rafters. Its hot, the nails from the roofing get in the way and depending on the real-estate you may not be able to maneuver the new rafters in. Trouble is as the collar ties go up the force to push the exterior walls outward is greater either causing a grin in the center of the rafters or knocking the exterior walls out of level and cracking the gypsum, base and flooring. I have also removed the closet row of decking nearest the ridge and pushed the rafters in from the roof, remember not to load all the material at once. For liabilities I agree with the other comment about the engineer.
good luck! let us know how it turns out.