Straighten Roof Trusses

A.Gilbert

I have 4 trusses, 2' centers that I built in 1979 that have bent down across the 17' span (in the front bedroom that is 10' wide with no center support) ,approx.11/2" to 2" at the middle. I will remove the gypsum panels and insulation and then I would like to raise the trusses until they are straight again.I just put on new shingles last spring on the roof because of leaks,they were 24 years old.

I temporally jacked them up a little to support them during the winter.

My question to you is can I jack up the four trusses together across the middle,approx. 1 1/2" until there straight across the 15' span, and then sandwich 2"x6"x 16' along both sides of each truss and either use 1/4" dia.x 5" bolts right though the both 2x6x16' and the bottom 2"x4" of the trusses about every 2' the 17' trusses or use 3" deck screws going in from both sides of the two 2"x6"x16' treated lumber 1' apart the full 16' . I hope this is clear enough.

Attached Thumbnails

   

Daniel Holzman

I am confused by your post on several points. First, you say "2' centers that I built in 1979". Do you mean you built the trusses yourself, or the house, or both? Second, you say that the span is 17 feet in the first sentence, then you say that the front bedroom is 10 feet wide, then in the second paragraph you say the span is 15 feet. The last paragraph makes little sense to me, perhaps if you attached a dimensioned sketch of what you propose to do it might make more sense.

When you built the trusses, did you perform calculations to determine the expected amount of deflection? Normally trusses are built by truss manufacturers, based on the span and loading requirements. Reinforcing a truss can be done, however you have to analyze ALL of the truss elements to make sure that you do not overstress any of the elements, it does no good to reinforce the bottom chord only to allow another element of the truss to fail.

A.Gilbert

Daniel,
I thought the sketches were attached, first the bedroom size is 15' x 10',the floor width is 17' or 17ft.,the loss of 2' is due to a cloths cupboard along the wall.The truss length is 17' BUT 15' UNSUPPORTED. I built the trusses and the second floor.The trusses have 2 ft. centers, the front truss is suported along the front outside wall, then 4 unsupported for the 15 ft. ,then one along the inside wall near the center of the house.Here is my email arnold.gilbert@sympatico.ca I could send you the sketches I used to build the cottage via email.

quote=A.Gilbert;424473]I have 4 trusses, 2' centers that I built in 1979 that have bent down across the 17' span (in the front bedroom that is 10' wide with no center support) ,approx.11/2" to 2" at the middle. I will remove the gypsum panels and insulation and then I would like to raise the trusses until they are straight again.I just put on new shingles last spring on the roof because of leaks,they were 24 years old.

I temporally jacked them up a little to support them during the winter.

My question to you is can I jack up the four trusses together across the middle,approx. 1 1/2" until there straight across the 15' span, and then sandwich 2"x6"x 16' along both sides of each truss and either use 1/4" dia.x 5" bolts right though the both 2x6x16' and the bottom 2"x4" of the trusses about every 2' the 17' trusses or use 3" deck screws going in from both sides of the two 2"x6"x16' treated lumber 1' apart the full 16' . I hope this is clear enough.[/quote]

jklingel

AG: It seems to me that you are going in the right direction, but I don't think adding a 2x6 is going to do much. After all: Think back to '79 when you decided to build a truss instead of sticking 2x6s across the span. A 2x6 on that span won't carry stink, and less-than-stink attached to a sagging truss does not sound like it will help. I'd suggest you build "new" trusses, by adding more braces to the braces you have. The big question is "Why did the truss fail in the first place?" Probably not because the bottom chord was too wimpy, I'd guess. Any lumber yards/engineers you could ask about re-bracing? Maybe your connection plates are too light? And when you jack the trusses up, jack them a tad high so they can "settle" into place. What is a tad? Dunno; 1/2"??

Willie T

One question. It doesn't happen to be the the trusses supported at 15' by the closet wall that are doing the sagging, does it? Or are all of them sagging?

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Willie T