Official Gramps' Memorial Eternal OT Thread

#72,681
#72,681
AM64 said:
So a question about structural repairs. At the other house I have a detached garage, shop, shed combo. The garage is two large bays, and the shop would be like a third larger bay separated by a wall and without a large door in the front. The shed is about 8 ft wide and runs the full length behind the shop and garage. The roofline is parallel to the front of the garage. Several years ago I drove over to help my son with something and noticed the roof had a definite sag in the middle of the ridge. Then a few months later when I was back and started to drive into the garage I noticed what I call a ceiling joist was hanging down. So the first thought was see what was happening and "stop the bleeding".

Since I'm not sure about terms, I'll do the engineer thing and define them. The wood beams coming down from the ridge to the front and back walls will be the roof joists (RJ) and the ones running from the front to the back of the garage/shed will be the ceiling joists (CJ). So it turns out when the garage was rebuilt probably 25 years ago after being crushed by a big oak, the builders may have taken shortcuts. If it was up to code, the code was faulty. The ridge beam and RJs seem fine and up to the task. The problem is that the main support that runs all the way down the middle of the garage/shop (directly below the roof ridge) and the ceiling joists are pretty iffy. The center girder (probably not the right word) is built up of something like four 2x10s or 2x12s - seems adequate but simply nailed together (not adequate). There are something like 2x4s - maybe larger nailed to the center girder. The CJs are attached to the outer walls and notched to sit on the 2x4s and are toe nailed to the center girder.

So the problem is that toe nailing works fine with things under compression - like wall studs, but not with things under tension. Over the years the roof weight (and wind loading - no doors on the garage) caused the front wall to push out and pull the CJs out of the center beam. Two of them moved outward farther than the 2x4 supports and were hanging down from the center. So to stabilize the whole thing, I put a couple of jack posts under the center beam so that section was supported by those and the center post. Then I put four jacks posts above them and the /garage/shop wall and tightened them just enough to slightly load the ridge. Then I put eyebolts in four CJs and used winches to pull things back together. The center beam had pulled apart in places, so I used threaded rod and large washers and bolts to pull those back together. I tightened everything in stages a little at a time because it was winter and I didn't want to cause any brittle fractures in the roofing.

I had my son crank things a little bit a couple of times a week until it was all stable again; then I removed the two jack posts in the garage and we started parking in the garage again. This was probably 5-6 years ago. The ridge is straight, but I haven't really addressed the issue of how to properly attach the CJs to the center beam or to put any intermediate braces between the roof joists (like the cross in the letter "A"). So for you guys in the know, what's the best solution at this point? What did the builder miss other than simply using nails in the wrong axis for a tensile load and not at least using joist hangers? I'm guessing that under static load it might have worked fine, but wind loading into open garage bays transformed the roof weight into a dynamic load - unloading the roof's downward force when the wind gusted in and then allowed it all to sag back down. Enough cycles and you get failure.
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only responding because it was addressed to me, but I think the guys covered it pretty well. I agree with what Marcus said. the collar ties are probably what's needed. That is the most likely issue & easiest/best fix. the hangers could help too, but tend to be more expensive and not great to install after the fact, especially if the roof isn't already plumb. and there are tons of different ones, and its impossible imo to know which is the best.

The one other thing to check if its an older garage to see if the foundation has settled. It may be a case of the wall has settled and pulled away from your joists. which caused the rest of the issues. you may have already checked that, or would have noticed it, but worth checking. I would check the whole garage, not just the effected area. could be the whole place settled down, EXCEPT for one area, and that is causing the issues. Settling happens, and generally isn't a problem, differential settling is where you get issues because it will continuously strain the rest. and that could pop the collar ties.
 
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#72,682
#72,682
one thing i will add about the collar ties @AM64

be sure you install them all at the same height/relative location on the roof or ceiling joists.

two best ways would be to go ahead and cut all the collar ties so you have the same size. if the roof is plumb that will ensure they are all at the same place, but if its out of plumb they may be further up or down from the rest.
the other way would be to run a line across the roof from two known (height) points at the far ends of the garage. just nails and taught string. and make sure all of your collar ties hit the line the same.

what can happen with older structures is the repairs can make it TOO rigid. and the new repairs end up fighting the rest of the structure. if you have the collar ties out of whack some could pushing while the rest pull. its best if you make sure its a consistent fix. but don't be shocked if the structure creaks and groans after you fix it, the sounds to worry about would be pops or sharp cracks. not likely, just something to be aware of.
 
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#72,685
#72,685
volfanhill said:
What's the move in these scenarios? Grab a few hours of sleep now or just power through?
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Well...

Had just dozed off when I started getting alerts of a tornadic storm headed right at us at 60 MPH. We had about 10 minutes warning and gathered people and pets into the interior hallway.

Didn't touch down thankfully, but there are tree limbs down and the power went out not long afterwards. It is still out this morning, but we made it through.
 
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#72,688
#72,688
So it’s become clear to me today I can do this contracting gig for as long as I can stand the stupidity.

I was asked to help diagnose a control loop problem on an assembly I am familiar with. Once we got the test bench functioning we had it figured out in about half a day. Easy peasy.

Today I find out they had scrapped five boards, about $5k each I’d guess, because they could not figure out the issue and make them work. I asked if they were specifically all scrapped for the singular issue I’d helped isolate or for various workmanship issues. Nope just for this one issue we figured out in no time!

I’m either going to get rich or go insane. Or both 🤷‍♂️
 
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#72,690
#72,690
NorthDallas40 said:
So it’s become clear to me today I can do this contracting gig for as long as I can stand the stupidity.

I was asked to help diagnose a control loop problem on an assembly I am familiar with. Once we got the test bench functioning we had it figured out in about half a day. Easy peasy.

Today I find out they had scrapped five boards, about $5k each I’d guess, because they could not figure out the issue and make them work. I asked if they were specifically all scrapped for the singular issue I’d helped isolate or for various workmanship issues. Nope just for this one issue we figured out in no time!

I’m either going to get rich or go insane. Or both 🤷‍♂️
Click to expand...

You were already insane enjoy being rich
 
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#72,695
#72,695
marcusluvsvols said:
Thats a very detailed description. Good job. Sounds like your " RJs " or rafters pulled away from the ridge causing the ridge to sag down and the exterior wall to bulge "out" a bit. If i underrstand correctly anyway. You have everything tightened back up now though right? If so, the answer IMO is to add what should have been installed when it was originally built...which are called "collar ties". Collar ties are horizontal 2x4s that run below the ridge typically 4 to 8feet...perpendicular to the direction of the ridge beam...just like in a capital letter A as you described. They exist specifically to prevent this issue from happening...and have no other purpose. They should have been there to begin with on any "stick built" roof not constructed using prefab roof trusses. Hope this sloppy picture helps.

* Sometimes collar ties are installed on every rafter, sometimes every 3rd rafter which is every 4ft. Depends on the slope/span of the roof and load etc. Sounds like you likely dont have much slope there if these rafters are spanning garage depth plus a room on the back...I would probably put 2x4 collar ties on every rafter if possible. 3in framing nails are plenty strong enough, 2 in each end of the 2x4s is normal.
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This happened to my father in law. The framers didn’t put those in and the vinyl under eaves started falling out. We went into the attic and figured out what was going on.
We used jacks to raise the roof and installed the collar ties and he hasn’t had any issues since
 
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