Truss horizontal bow


Observing the truss installation in the attic we noted various trusses have bowed (especially on the south side). At the time the home was built “truss spacers OR spreaders” to help prevent this condition were not commonly used and many framers were “stick builders”, not truss builders. We recommend consulting with a general contractor specializing in “truss construction” to see if it is recommended or cost effective to modify these.


I would cover my butt and make mention that the trusses have been installed bowed and may have some effect on the gusset plating that is the structural part of it. Recommend a structural engineer. I see it all the time. There was a company during the 80’s boom would leave the trusses laying out in the weather for months ,might i add not laying flat. They would be so warped and twisted there was no way to install them straight. Good chance they may stand another 40 years if only we had a crystal ball

Your point is obscured just like it would be for you trying to determine if there is a problem with a crooked truss. You can’t identify a problem, you pass it on to someone else because you don’t know just like a bunch of other guys. PE’s must be in high demand in your area too.
You should have stayed a laborer in construction a little longer before becoming an inspector.

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Stack of truss probably on unlevel ground for awhile before installing and left these bowed areas you are seeing. They are probably all bowed in same place. Sheathing isn’t plywood so they didn’t take the time to straighten each truss. It is really a non issue. It is not some defect that happened after construction over time. Note it and move on.

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OK ,so the truss manufacturer sends the trusses out on a roller trailer and unloads them with a dump action. This causes the plates to pop. Most framers will use a block of wood and press them back in.
also the framers are to nail the rafters in as straight a line as possible 24 on centre usually. But this side of the roof was put on in a hurry , Friday afternoon, Beating a wind or rain storm, most likely. lol. and yes every 4 feet , two rafters, it will be in line with the seem ends of the sheathing. I was a contractor for 30 years. I would mention it in the report and if the shingles are ready for replacement recommend repairs and straightening be done then. Also recommend that they get several quotes on the job and suggest adding more insulation at the same time.

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A portion of the homes foundation has settled or heaved. Garage in that bowed section.
I did not bother going though all the posts.
Refer to a licensed structural engineer for immediate analyses. Danger of roof failure.

All the best.

I always enjoy your posts, Marcel. You add sanity to them!

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Still enjoying the truss show Larry?

Here we go again:

Evan - you’re getting conflicting advice similar to the recent post about trusses. What your pictures show is pretty common. Trusses almost always have some bows and waviness to them from being moved around during delivery. Think about this like someone who is installing the trusses and roof sheathing: After the trusses are craned in place and secured with blocking, the fascia boards are installed and the plywood sheathing begins. Typically the sheathing installation starts at the bottom left corner on each side of the roof. The framers snap a chalk line across the entire side that is about 48" up from the fascia to establish a straight line to keep the sheathing from twisting out of line during installation. As the first row of sheathing goes on, the truss layout is marked on the top of each sheet of plywood. These marks show the framers where to locate the trusses based on the 24" OC layout. The first sheet of sheathing is nailed on the chalk line at the bottom left corner, then each truss that connects to this piece of sheathing is pushed around by the framers until it lines up with the marks. This keeps the trusses spaced evenly. The first row continues like this, and then the process is repeated as you go up. The framers push the trusses around each time as they install a new row of sheathing, trying as best as possible to stay on the 24" OC marks. Sometimes as they’re doing this, the layout of the trusses gets off a little bit. They are bowed a little too much or can’t be pushed far enough to get perfectly back on layout. As they sometimes get a little bit off the marks, maybe a 1/4" here or there and it compounds as you go up, you see some waviness in the truss below, like in your pictures. As you go up the roof, each row of sheathing below is nailed and it gets harder and harder to move the trusses around on layout. This is all normal, and some small amounts of waviness like this are NOT a defect. As long as the trusses are cross braced together properly and have gable braces that reinforce them all together, they will act as one system, and the bowing seen here will have no effect on their ability to perform. (I wonder how many of you look at the cross bracing and gable bracing) There is no need to call a SE about this. If the gusset plates are loose, recommend a contractor to fix those, but the bowing is normal.


Grandkids need me these days but there is wifi at some of the places I take them e.g. dentist, Taekwondo, etc.