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How to repair cracked joists


Tom McMahon's Avatar
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12-17-13, 07:19 PM   #1  
How to repair cracked joists

Some background: my house was built in the 1850's and appears to be of a timber, or post and beam, construction. Further, the ends of the joists in the house were notched to lap into notches in the perimeter beams.

I removed a section of the ceiling on the first floor to redo the drain plumbing from the 2nd floor bathroom. When I did, I discovered that the joists I exposed have significant cracks emanating from the inside corner of the notch. What is worse, these joists had notches cut in their tops to route the aforementioned drain pipe. The joists are 6-1/2 inch high by 2-3/4 inch thick. The height of the joist notches are 3 inches. The horizontal distance from the end of the joist notch to the notches cut in the top of the joists is 7-1/4 inch and those plumbing notches are 2-3/4 inch deep. (All measurements are actual, not nominal.) I have attached a diagram and photos of both sides of the two most visible joists.

2 questions:

1. How freaked out should I be about this discovery?

2. How do I fix it?

Any helpful input will be most appreciated. Thank you!!

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XSleeper's Avatar
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12-17-13, 08:04 PM   #2  
Not cool. At a minimum, I would definitely jack the joist up to close the crack and then install a couple double 2x8 hangers (LUS28-2Z) on each end, so that the ends of the joist are better supported, which will help the joist resist cracking at that location. Does the notch for the drain pipe need to remain in use? I think I might also bolt a steel flitch plate to each side of the joist with 1/2" bolts.

 
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12-17-13, 08:39 PM   #3  
Installing joist hangers is a good idea. I can't use standard joist hangers since the joists are not standard lumber. I will have to find some that I can modify to fit without destroying their integrity.

I have no idea how I would go about jacking up the joists. Directly below these joist ends is the kitchen sink. But, more importantly, the first floor is supported by similarly notched joists. So, jacking up the cracked joists 3 or 4 feet from the outer wall will transfer the load of the house from the supporting outer wall to the first floor joists. I'll have to give this some thought. I don't want to solve one problem by creating a bigger problem.

You have given me some very helpful suggestions and helped me turn the corner from panic to a problem solving mindset. Thank you.

Oh, those unfortunate plumbing notches: I had just removed the lead tub drain pipe from those notches and was preparing to replace that lead drain pipe with PVC. I'd much rather bore holes through the middle of the joists but then the drain pipe will be lower than the nipple in the cast iron stack that I need to connect to. The simplest of projects in an old house like this grow into much larger projects and seemingly can easily devolve into a full tear down and rebuild if you're not careful. :-/

 
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12-17-13, 08:58 PM   #4  
I took a closer look at the specs for the joist hangers you suggested. Width is 3-1/8 inch which is 3/8 inch wider than my joists, but i may be able to deform the hangers around the joists to fit. My bigger concern is the landing depth which is 2 inch. My joists are not flush with the perimeter beam; there is a 1 inch gap between the end of the joist bottom and the beam with one joist and a 1-1/2 inch gap with the other. So, the joists would only be supported on the outer inch of one joist hanger and the outer 1/2 inch of the other joist hanger. Do you know if there are joist hangers with a deeper landing?

 
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12-18-13, 03:33 AM   #5  
If the hanger is 3/8" too wide - add plywood to make up the difference. I'd cut the plywood long enough to more than span the length of the crack to help hold it tight after you jack it up. You might try building a temporary base to span the sink to jack off of - take it slow and easy and resupport the base as/if needed.


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12-18-13, 05:32 AM   #6  
Thank you marksr. That did occur to me after I posted. And while lying sleepless last night, I thought of this: screwing a large steel plate to either side of the joist in the area of the crack in addition to the joist hanger. Any thoughts?

 
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12-18-13, 06:26 AM   #7  
while lying sleepless last night, I thought of this
That's what a flitch plate is. Like I said, I'd probably bolt that steel plate onto each side. If you used 3/16" steel on each side, that would be your 3/8". Make the steel full length so it sits fully in the joist hanger. Don't just reinforce just part of the joist with a short piece of steel, reinforce the whole thing. Notch the steel for the pipe if needed.

Building a long header to sit on the countertop will spread the weight out and span the sink. Shim up the header with large scraps of plywood so that the bottom of the header doesn't touch the rim of the sink. Then you can place the jack on top of the header, directly over the sink, if needed.

 
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12-18-13, 06:26 AM   #8  
There is no need for a steel plate.
That needs to be lifted back in place with a bottle jack sitting on some blocking. Add some Tite Bond II to the gap first.
Once it's lifted I'd add a full length of 2x that runs all the way over to where it connects.
I like to use construction adhesive and 10 d nails every 6" to make the connection. Sometimes you have to use a clamp to pull them together.
The hanger I use is called an old work hanger. Simpson makes them.
When I can not find them I use the hangers made for LVL's since there wider.

 
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12-18-13, 09:39 AM   #9  
"I think I might also bolt a steel flitch plate to each side of the joist with 1/2" bolts." Yes, XSleeper, you did. I guess your idea didn't sink in until I was lying sleepless in the night. Apparently I latched onto the joist hanger idea when I first read your post and focused exclusively on that. Thank you.

 
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