Has anyone done this modification? I plan on running 2x8” rafters along both sides of the 2x4 against the roof and then using a collar tie on the upper portion of the rafter. I will notch the end resting on the wall and butt the upper ends together using a 1/2” plywood piece, glued and screwed on the upper ends. I am only modifying 3 of the trusses in order to raise the car on the lift. Does this sound reasonable?
Make sure you do the mods/reinforcements to the trusses BEFORE you cut out the ceiling joist portion for those three, and I think I understood that you were 'tying' the three cut/reinforced ones into the adjacent trusses on each side of the ones you plan to cut - and that's a good idea you should do!
'55, '56, '57 Nomads North Alabama area Gary
Last edited by BamaNomad; 05-16-2019 at 07:55 AM..
SoCal, I guess snow load isn't a worry. With your plans keep in mind that it will want to push outwards on the walls. Picturing that force is the main thing you want to prevent. You may have those big staple plates in the way, but I'd try to run a light weight center beam of sorts the length of the cut plus 2 more on each side. Or if those plates in the way 1 2x6 or even 2x4 on each side of the peak. Here's a trick. Buy lumber that is dry and warped, then attach each end first, with the warp pushing upwards in the middle. Use a jack if needed, then attach it in the middle ones.
Actually the house I grew up in built in the 50's had a large vaulted ceiling in the large living room. At each end where the vault stopped, up in the attic it had cables to help keep it from spreading the walls. They can do much more than reinforcing the other trusses since you can tighten them with a turnbuckle to give them preload. Tighten them til they twang like a banjo.
You don't need the 2x8's. Just reshape your trusses before you cut anything out as mentioned. 2x4's and truss plates or plywood and glue and screws. To elaborate, put 2x4's along side of the existing trusses in the shape of the vault. Then cut the existing truss out and add 2x4's in the truss plane.
It's amazing how strong a truss is. I built my house using 44' pre-built 2x4 trusses with a 7-12 pitch roof. The front half of the truss was vaulted as in the "vault" picture. When I set the trusses on the walls, I found out the concrete under the center wall was 3/4" inch higher then the outside walls. I though I would just fasten one end to the top plate and pull the end of the truss down with a clamp. It pulled the opposite end of the 44' truss off the top plate. I ended up notching the center wall for the truss.
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Thank you for the replies. I think I am on the right track and I appreciate the pictures in you discussion acardon. Good to know I donít have to use the 2x8. Itís a 13í run for the rafter and the 2x8ís would be a hassle. I will take some measurements and see if I could make a scissors truss work. Thanks again for the help. Iíll try and post some pics of progress.
It's going to be difficult to say the least to *rebuild* the trusses in place. Those metal plates give amazing strength but they normally put them in with a press. I've tried hammering them in without any luck. With whatever you do, just always picture it as the top (ridge) pushing down and the ends are trying to push the walls outward. That may sound a little extreme, but it's an easy way of looking at it and understanding what you need to do to prevent any problems.