2x10 Repair 1

[SeattleME]

Hi Everyone,

I’m a mechanical PE and could use some advice on the structural repair of a botch job an electrical contractor did at my house. I’ve attached some photos for reference.

I have about a dozen 2x10 floor joists over my garage. The kitchen is directly above the garage. The 2x10 joists have a span of approximately 17’-6”. An electrical contractor bored 2-inch diameter holes through the bottom section of the beams all the way across my garage. He installed a 100-amp subpanel on the other side for EV charging. The holes left about 1/2” of “meat” between the lower quadrant of the hole and the bottom surface of the beam. The holes are about eight feet from one end, positioned in the middle third of the beam. In effect, the electrician turned my 2x10s into 2x8s.

I’m in King County, Washington State, where the IRC is applicable. The IRC says no holes in the upper/bottom two inches of the joist. The inspector did his inspection via camera phone (didn’t even look at the joists) and passed it. I didn’t notice the issue until after the electrician left site (shame on me - wife says it’s my fault, but then again isn’t everything).

I will be proceeding with a repair for peace of mind, if nothing else. I don’t like the idea of reducing the load capacity of 2x10s that were already probably at max span. Especially not in my kitchen where people tend to congregate during social events. I’ve contacted the contractor but haven’t heard back yet. If he doesn’t agree to pay for the repair, he’ll be hearing from my attorney. I’m a forensic engineer, and as much as I don’t like to admit it, I know several dozen.

My questions (and thanks for reading this far) are:

1. Does anyone have any experience with joist reinforcement plates like those offered by Skyline Joist Repair (

http://www.joistrepair.com)?

While they look they’d work, the company has zero certifications and makes no code compliance claims whatsoever. However, if properly installed with screws and two-part epoxy, they look like they’d work okay as long as they more than make up for the deficit in the lost section modulus of the beam.
2. Would it be better to sister two 3/4” sheets of A-bond plywood on either side of the beam? Screwed and glued, of course.
3. Should I jack and level the beams before applying the repair in order to unload the beams near the stressed area? I don’t like the idea of encountering a flexural stress failure in the beam due to lack of composite action between the beam and the reinforcement plate or sisters.

Before someone suggests placing a Simpson strong-tie over it, I’ve read multiple opinions of SE’s saying that this won’t work due to the beam’s preload and lack of composite action between beam and tie; i.e., the beam will fail in flexure, then the load shifts to the tie, and then the tie fails — and all without any apparent increase in load carrying capability. Empirical evidence appears to support this position. There is a report from the 1970s where they tested metal straps running along the bottom of a joist. The straps were installed the full length of the joists. They found it didn’t help — the straps and wood failed independently of each other.

Appreciate the advice.

 

[KootK]

What an awful thing to have happened to an engineer with structural knowledge. Two things to consider:

1) What you have now is worse than a 2x8 because a real 2x8 would be properly graded such that it would not have defects near flexural tension edge. You could, I suppose, have a lumber grader come in to check out the situation.

2) Partial length sistering usually requires a gaggle of concentrated fasteners at the ends to transfer the shear out of the reinforcement and back into the piece that was reinforced. In my experience, when left to their own devices 100% of contractors and 70% of engineers will not do/specify this.

I’ll likely sue the electrician for damages, anyway. But I’d also need to justify the repair later on in the lawsuit.

For sport, I'm going to tell you what I would want if this were my house without worrying about whether or not this is in any way likely as an outcome. I would want to be made whole in this sense:

a) I would want the repair to be as strong as the original construction. Not just strong enough to satisfy code.

b) I would want the repair to be as stiff as the original construction, not just stiff enough to satisfy code.

c) I would want the repair to be as reliable as the original construction. No goofball solutions that probably introduce a bunch of stress risers that will not be accounted for.

d) In the unlikely event that a prospective homebuyer spotted the repair and gave a crap about it, I would like to be able to say -- with a straight face -- that the repaired condition represents an improvement over the original condition. A screw up by someone else shouldn't mess with the resale value of my home.

One of the very view ways that I feel that this could be achieved is shown below, viewed from the top. Double 2x8 sistering. This is what I would be seeking for restitution if I felt confident that I would be successful with this in court. You're likely in the best position of all of us to gauge whether or not that is a realistic expectation. No doubt the defendant will have their own structural engineer expert witness saying that this is gross overkill.

I feel for you, I really do. I have one wood truss in my attic where a couple of the plates have popped off. I doubt that I go a week without thinking about it and being bothered by it. Sadly, I've no one to sue.

 

[RattlinBog]

How are your joist ends supported? That detail could make or break installing new full-length joists. Consider your existing electrical, plumbing, and HVAC in that area. Can you physically swing in a 14 ft joist between all the utilities and other obstructions? You're below the kitchen, so I imagine you'll have some busy spots. Can you even bring in a 14 ft joist into the area? I'm assuming yes if it's a garage and no stairs and turns to navigate... Just think about it a little and take some measurements. Imagine yourself working with whatever length (partial or full) sister joist in that area and see if you even have the needed clearances.

A full-length joist is unlikely to just pop into place nicely. There will be jacking at each end and middle, sledge hammer pounding, adhesive dripping all over you, and swearing involved...ask me how I know... (Not that partial length is much easier, either.)

 

[dik]

Can you have the contractor provide you with a sealed repair?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SeattleME]

Thanks everyone for all the great replies.

Lexpatrie — Thanks for putting it more clearly. Anything less than pre-loss condition is unacceptable. Through the course of this thread, it has become increasingly clear to me that a partial sistering of the joists is not the pre-loss condition.

That joist repair stuff "looks nice" but where's the ESR? Where's the engineer's seal for a proprietary reinforcing product? These guys are selling before they are really supposed to. You outside a code area, it's a shack? Go ahead, use it. (Look at all those screws!).

That made me laugh. It’s the Shack-Tek 2000. Order now and they’ll throw in a free bucket of screws!

KootK — I’m thinking double sistering would be a wash from a construction cost standpoint when compared to doing a full 2x10 single sister. The only electrical lines passing through this area are the 100-amp cable that caused the problem and a 120 volt NMB conductor running to the garage door opener. There is also a natural gas line that the previous owner installed below the hard lid that I’ll probably reroute through the center of the joists. Otherwise, the double sister would make sense if it was a congested area.

RattlinBog — The subject area isn’t congested as stated above. Fortunately, there’s probably not a better spot in the house to do a full joist sistering. The ends are supported by the top plate and garage door header on the exterior wall, and on the other end there is a beam and column that spans the garage to the interior wall of the stairwell (see figure below). I know it’ll be a PIA, but I won’t be doing it myself. I’ll be hiring a framer to do it.

Dkl — If I was doing a partial sister, I’d definitely require the contractor have an SE design, stamp, and inspect it. As lexpatrie pointed out, full sisters wouldn’t require a sealed design since it wouldn’t be an engineered design.

 

[SE2607]

For my two cent contribution, I agree with:
1. Relieving the load prior to reinforcing. This will ensure the reinforced section sees stresses from actual dead load.
2. 2-2x8s are as stiff and strong as a single 2x10, so a single 2x8 sister attached to the existing joist with (2)-1/4" dia. Simpson SDS screws at 12" (max) should suffice. Of course, 2 would be better. If you use 2 sisters, stagger the SDS screws. The longer the sister(s) the better. That would make the transition of the load into and out of the sisters lower thereby reducing long term creep.
2. The person who did this should either be taken out and shot or, at minimum, lose his/her contractor's license. If it were me, I would file a complaint with the state contractor's board.
Good luck with your repair.

 

[phamENG]

If it's not congested, then I agree that removing the cable, installing new joists, and drilling correctly would be the best answer. A few potential issues:

1) I see some duct work in your photos. I bet that's part of why the electrician ran it that low. Do you have room to snake around that and stay in the correct part of the joist?

2) Dimensional lumber shrinks and crushes in service. You're going to bring home a nice stack of fresh 2x10s that may not fit at the bearing points.

3) Your floor has some deflection to it already, so the shape of the existing joists will not match the shape of the new joists, exacerbating the shrinking/crushing problem. Jacking will reduce this.

I'd probably go for double 2x8 sistering if single 2x10 had to be notched to install.

 

[EdStainless]

After you talk nicely to the electrician then you can decide,
If he is being a dick about it then you can always file a lien against him.
You might not get any money but for a while it will make his life difficult.

My Dad had a similar thing happen to his house, but he noticed after they drilled the first one.
He asked if 'that was the approved location for that size of hole?'
Followed by 'show me the plans'.
The guy quit for the day and came back the next, repaired the first hole and began putting smaller ones in the correct locations.

Sounds like the inspection failed to cover unauthorized structural modifications.
If you have the time, I'll bet that you can make stink of that also.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[stevenal]

[URL unfurl="true"]https://lni.wa.gov/licensing-permits/contractors/problems-with-a-contractor/filing-a-lawsuit[/url]

 

[SeattleME]

Thanks, EdStainless. It’s good to know the L&I process. Getting the electrical contractor to pay to fix it without a lawsuit would be optimal.

I think they did what they did because of an HVAC duct that was in their way. They should have removed the round duct and replaced it with low profile rectangular duct to make room for their cable.

I was just down in the garage looking at what they did. Of particular concern is the location where they cut into the double joist that supports the top of stair stringers (see photo). That’s not going to be an easy repair.

Question: If they do a full 2x10 sister and have to notch the ends to get the joist in, why is that necessarily bad? The ends of the joists are in shear, right? Would a 1/16” or 1/8” notch really have that big of an impact?

Here’s a better photo of the stairwell and the joist support walls:

 

[phamENG]

Question: If they do a full 2x10 sister and have to notch the ends to get the joist in, why is that necessarily bad? The ends of the joists are in shear, right? Would a 1/16” or 1/8” notch really have that big of an impact?

That's one of those pesky wood issues. Yes, it's in shear...but due to the grain orientation and lack of strength, you can end up with significant splitting issues where it's notched. If the notch aligns with a particularly wide and/or weak grain or the notch is over cut, the new joist can split along that notch. Code allows it, but I've seen code allowable bearing notches fail before.

The long screws I mentioned in my repair suggestion above are there to prevent this kind of failure.

In the grand scheme of things it's probably not going to be the end of the world, and as long as you adequately fasten the new to the existing, the existing will take the reaction and prevent the other one from splitting. So perhaps I made a mountain of a mole hill on this one...sorry...habit!

 

[SeattleME]

Regarding the cost of repair, my wife has already told me to go ahead and spend whatever it costs to fix it correctly. We are quite well off (no thanks in part to my engineering career), so having to wait to get reimbursed from the electrical contractor isn’t a concern.

As of right now, I’m going to call in a structural forensic engineer I know to document the damage. He works for a different firm than I do, but we’ve known each other for years.

After that, I’m going to start soliciting bids from GCs to rip out all the drywall and install full 2x10 sisters, reroute the electrical, modify the HVAC duct, and then reinstall everything per code.

What a shit show.

 

[SeattleME]

The long screws I mentioned in my repair suggestion above are there to prevent this kind of failure.

Got it. Makes sense. Thanks for the suggestion. That’s exactly why I came here. I’m more familiar with web crippling of steel beams than I am with splitting in wood joists.

For fun, I went upstairs and measured my kitchen floor. It slopes towards the location where the joists were cut. The floor has a 0.3 degree slope on the long side of the span, and a 0.5 degree slope on the short side of the span. If it was ever level, it isn’t anymore. I hope it doesn’t crack the tile.

 

[SWComposites]

Strongly suggest that you be there in person when the GC or whomever is doing the repairs. Who knows what “surprises” they will find when it is fully opened up. You don’t need another “OMG what did they do” situation.