I'm confused.
Is the "beam" you are referring to in the lower left of the picture right above the yellow romex that loops to bottom of the picture?
If so, why does it look like wood? It looks like it's a piece of wood with possibly a steel plate attached to the face of it.
Not that that has anything to do with the repair of the joist. It's just that it doesn't look like a "beam", at least not to me.
Am I missing something?
At a maximum inch and a half embedded the lag would not be nearly as strong as a bolt through a correctly sized hole. Not even remotely.
R
Any polyurethane construction adhesive would do.
R
They knew exactly what they were doing. They knew they didn't give a damn and wanted to be finished as quickly as possible.
R
But in this case would it matter? Serious question, I'm no structural engineer.
With a 2 x 8 sistered across the notch, extending let's say 2 feet on each side, and then glued and lagged in, let's say, 4 (6?) places on both sides of the notch wouldn't that be more than enough to fix the current problem?
Would bolts really add anything worth considering or would they amount to overkill?
Of course, that's not to say that bolts wouldn't actually be easier to install.
There is a 2X4 resting flat on top of the I-beam that runs the whole length.
Oh...I see it now. It's an I-beam and that bundle of wires runs under the top horizontal.
I didn't notice the rust on the vertical part until just now.
Thanks!
I wonder why they used a 2 x 4 on top of it. Just seems like something that could crush of a joist was positioned on a soft spot. In my house they set the ends of the beam in a bed of concrete to get it to a height where the joists rest right on the beam.
A two part epoxy is even better. Sister the joist on both sides with
3/4" plywood of substantial length and the lost strength should be totally recovered.Joe
That close to center beam, and to the fully-supported joist on outside wall, unlikely to fail catastrophically. But just on general principles, I'd sister it anyway. From over the beam to maybe 18-24 inches past the notch. A couple 16s to baste it in place, then some staggered carriage bolts on each end. If that isn't possible, then a 2x4 or steel strap lagged into the bottom of the joist to take the stress off of the cut section. Unless a 4-foot level on the floor upstairs shows any sag, I wouldn't even bother to jack it. Hard to say what it was for, without inspecting the space for other clues, like on the outside wall. Maybe a long-gone oil fill line?
I've seen worse, in more critical locations. Held fine for years, then one day somebody walks through carrying a piano, and 'crack'. Carpenters have long been of the opinion that plumbers and electricians should be prohibited by law from owning sawzalls.
Yes, that'll work. Don't be shy with it.
Hank
For Mike,
After 30 years it has done all it is likely to do, but I agree with both you, I would scab it on each side if possible extending 18-24" past the notch. Thereafter I would forget about it.
It won't twist.
So I guess the assumption is that a new piece of 2 x 8, glued and screwed/lagged/bolted to one side would have enough strength to twist the existing joist if it should twist as it aged? I can see that, especially with the notch cut out.
How about if 2 layers of 3/4" ply were glued up and used on one side? That wouldn't twist would it?
Would that be stronger than a single piece of 3/4" on each side?
Just curious, that's all.
If 2 layers of 3/4" ply were used as the sister, glued and screwed
Why sister both sides? (ideally)
It's a symmetry thing. The original un-notched beam was symmetric with respect to the vertical load it carried. Sistering only one side creates a non-symmetric joist. Probably a minor / second order effect but symmetry is ideal.
Adding 3/4" plywood to both sides of the joist restores symmetry to the system.
The chief engineer I worked with for nearly ten years taught me "God likes symmetry".
To repair the joist I would jack the notched beam slightly (to sister a member without relieving the load by jacking leaves the sister unloaded by the existing load). I would cut two sisters from 3/4" plywood, glue and mechanically fasten in place. As per other posts, the plywood should extend at least 18" beyond notch.
My choices of fasteners would be.
1) Senco M2 style staples; 2" o/c all directions, both sisters. 2) .148" dia plywood shorts; 3" o/c 3) Simpson SDS 1/4; 4" o/cTo get the sisters to take load you have to transfer shear from the notched beam to the sisters. That means jacking & good tight fastening (glue & staples, nails or lags). Bolts are typically installed with over sized holes, not the best way to transfer shear.
Keep the jack in place until the glue dries.
cheers Bob
What is number 2?
I'm not a structural engineer, but I'd say no. Symmetry is your friend.
I don't believe two layers is twice as strong as one (fasteners, glue joint, etc.) Opposite sides would have twice the fasteners and glue. ...though I don't think the fasteners do much here.
I should have been more clear. I meant the gray object at the top of the photo that seems to be running parallel to the notched beam.
HVAC duct running inside the joists
Maximum strength.
"Plywood shorts"
They are short nails designed for attaching plywood (normally 3/8" thru 1/2" thickness) to framing.
The theory being, no need to have a full length nail to attach plywood. They are really for shear walls but they will work even better in a static loading situation like this repair. The nails are just needed to transfer shear between the sisters and the damaged joist so no need to go crazy on the length.
The shorts are less likely to split the receiving member.
cheers Bob
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