Repairing butchered joists

[branimal]

I ripped out two bathrooms in a small multifamily home I’m gut renovating and found the prior contractor notched the joists to run toilet plumbing.

The notches are fairly close to the boundary wall of the building. My building is attached on both sides.

All the old plumbing has been ripped out. I am installing two new bathrooms in this area. I’ll be replacing the floors in this area with two layers of 3/4 plywood. One layer will be advantech.

Any recommendations on how I should go about repairing/bracing the joists?

I’ll get better pictures tomorrow with the plumbing pulled out.




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[spudley]

If replacing isn't possible, I've seen notched joists sistered with 2X material glued and bolted on. The new joists should be sized to reach bearing points.
Also seen 3/4 ply sistered on either side.
Is this getting inspected?

 

[branimal]

If replacing isn't possible, I've seen notched joists sistered with 2X material glued and bolted on. The new joists should be sized to reach bearing points.
Also seen 3/4 ply sistered on either side.
Is this getting inspected?

No inspection.

I’ve done 2x sistering glued and bolted in the past to level joists.

I was reading about 3/4 ply sistering on either side. Is it as reliable as the 2x method?

Thx





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[JoeMcGov]

No inspection.

I’ve done 2x sistering glued and bolted in the past to level joists.

I was reading about 3/4 ply sistering on either side. Is it as reliable as the 2x method?

Thx

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Based on the pictures and the minimal loads I would expect (you haven't mentioned an above floor bathtub intended for this area) you would be totally fine with sistering with 3/4 ply material. Run it to the perimeter sill as mentioned.

 

[branimal]

Here’s the planned load:




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[larry4406]

My house had similar (though less severe) plumber vandalism that I found after purchase.

I sistered the wounded 2x10 joists with two ply's of 3/4" plywood 8' long glued and nailed to the joist, one per side. Your joists look wider than 1.5".

I ripped the plywood to the exact depth of the joist. I ran a taught chalk line from bearing point to bearing point on the joist span, jacked the wounded joist up until it was straight, then applied the scabs. Only after fully nailed did I release the jack. Was slow going one by one.

 

[theoldwizard1]

We have seen the "before", I would like to see the "after" !

 

[branimal]

@larry4406

IIRC my joists measure 2 3/4”x 8” Does that width require 2”x8” on each side to sister properly?

Is your pic from above or below the joists?

Not sure what I would brace against if I needed jack up the joist.


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[James-W]

What is underneath the floor joists? Is there another room down there, a basement, or is that the bottom floor and there isn't anything under there? Reason why I am asking is that if you can get under there and remove the old joists you could run new ones and it would most likely be easier that way. Adding plywood to each side or by adding a 2X along the side of the old ones would work just fine, but I think to get any kind of construction adhesive to stick you would need to clean the old joists and that may not be as easy as it sounds.

I guess I am just thinking out loud here and perhaps my thinking is a bit overkill, but sometimes tearing out and starting over is quicker and less expensive in the long term. In any case, I wish you all the best of luck in this endeavour. I tend to think this is going to turn into a bigger job than you originally anticipated.

 

[LXCam]

So if I read you correctly those are 8ft long? If so, considering the span, the width and the on center spacing i might not do anything. Have you laid a straight edge across these to confirm they've belled?

 

[larry4406]

@larry4406

IIRC my joists measure 2 3/4 x 8. Does that width require 2x8 on each side to sister properly?

Is your pic from above or below the joists?

Not sure what I would brace against if I needed jack up the joist.





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My picture is taken looking up from the basement below. I was able to use the basement slab to support my automotive floor jack with a 4x4 post then used to push up.

In my case, my joist was 1.5" wide by 9-5/8" tall. Thus my two ply's of 3/4" was equal to the width and I ripped to match the height. As such, I replaced the original section. On one end, my joists were hung from a beam with hangers; thus my approach changed it from a single to a two ply joist and double joist hangers then fit just fine. I had a demo permit and my inspector was content with what I had done. Yours all look like vintage rough sawn material from land before time so my approach of replacement of section in kind may not be appropriate.

James-W is on-point with thinking it may maybe easier for you to replace vs cleaning joists for scabbing depending on access. I agree with James-W that this looks like it will spiral out of control.

Wish you the best of luck with this one.

 

[JoeMcGov]

So if I read you correctly those are 8ft long? If so, considering the span, the width and the on center spacing i might not do anything. Have you laid a straight edge across these to confirm they've belled?

Glad someone else noticed that too. Boy. Those were the days where you framed a floor like that and with wood like that. WOWZER!

 

[branimal]

I was quoting the joists dimensions not the length. I corrected it above.

I’m guessing the overall length of the joist is close to the length of the building.... 20’

Below the butchered joists is a dropped ceiling to accommodate for plumbing. Below that is the 2nd floor bathroom.

I haven’t checked for level yet.



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[acer66]

Glad someone else noticed that too. Boy. Those were the days where you framed a floor like that and with wood like that. WOWZER!

Yeah, part of my house was build in 1911 and they used 2x8’s 24oc with a 15’ span but then again they also used tree trunks as pillars to hold the house up off the ground.

 

[acer66]

My house had similar (though less severe) plumber vandalism that I found after purchase.

I sistered the wounded 2x10 joists with two ply's of 3/4" plywood 8' long glued and nailed to the joist, one per side. Your joists look wider than 1.5".

I ripped the plywood to the exact depth of the joist. I ran a taught chalk line from bearing point to bearing point on the joist span, jacked the wounded joist up until it was straight, then applied the scabs. Only after fully nailed did I release the jack. Was slow going one by one.

Is sistering up with plywood up to code?

 

[theoldwizard1]

The plumbers did not "attack" the joists in my sons house, but water did !

The previous owner had installed a sliding shower door that leaked. The floor was vinyl on plywood. After years, the plywood got spongy and the joist underneath rotted almost completely through ! We sistered another 2by of the same dimension, glued and screwed it to the first. The joist actually spanned between 2 block walls. We could not get the one end into the pocket over the block wall, but there was a nearby by partition wall we rested it on. That wall is probably not carrying any of the load because of how we sistered the two together.

The floor was replaced with all new plywood, cement board and ceramic tile. That sucker will not leak through !

 

[Jim greengo]

I've used these on walls where guys got carried away before,not sure if they could used on a floor joist though.
Maybe they have something that would work.

 

[branimal]

Took a level to the joists yesterday. Surprising it’s fairly close to level with the exception of that really butchered joist that twisted and is sitting low when compared to other joists.

I’m going to buy some 2x8 and sister up what I can to provide some more support.

When installing a new subfloor for a bathroom do you guys use 2 layers of 3/4” plywood or just one?

I’ve used 2 in the past. Regular ply for the first layer, advantech ply on top. But that install had a bathtub.

There will be no tub in this bathroom. Just a shower, toilet and vanity.






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[larry4406]

Is sistering up with plywood up to code?

I build new homes, residential construction. On the job our stamped repair details for trusses and joists are most often done using plywood (not OSB) with glue and proper nailing patterns. That said, I proceeded as described and my inspector had no issue with what was done. So I would say yes.

 

[acer66]

I build new homes, residential construction. On the job our stamped repair details for trusses and joists are most often done using plywood (not OSB) with glue and proper nailing patterns. That said, I proceeded as described and my inspector had no issue with what was done. So I would say yes.

Cool, another day I learned something and I was about to give up on this day.

 

[3onthetree]

If the hack cuts are less than half the 8" depth, and you can get a 2x across the whole house to bearing support, then nailing 3 high @ 12"o.c. alternating toenail angles should be good for just one 2x for each joist (no need to sandwich). I would also put solid blocking cutting the house span in 1/3's to spread the load (since the plumbing is under the joists). I would not use plywood in a potentially moist location, and its use in trusses is a different situation. I personally don't use 2 layers of 3/4" subfloor, I match the 3/4ish old 1x floor, then use 1/2" cementious board under the tile (the subfloor doesn't support a tub, the joists do).

Unsolicited, but your work could be much easier if your bathroom(/house) layout was looked at by an architect or designer. I'll just say "coordinated simplicity" in the layout would allow for less work in Mech/Elect/Plumb/finish work/etc =less money X 3 floors, and could cause higher rents and resale. I won't comment on the non-inspections, but I hate to see so much hard work done yet the little "fires" distract from big-picture thinking.

 

[branimal]

Okay I'm finally getting around to sistering & leveling the joists. I was wrong on the levelness of the joists. Level parallel to the joists is off by an 1 1/2" over 96". High on the brick wall and low at the future entrance to the bathroom. See pic below. Makes sense as this is close to the center of the building (19' joist span). I'm only going to level inside the bathroom.

Level perpendicular to the joists is acceptable.

I started leveling to get a feel for the process today. Just two screws into the old joists for now. Will sandwich and bolt /glue next. See pics.


1. Why is gluing sisters to the original joists important? I've glued and bolted in the past but never understood the gluing part .... @James-W has me worried that my glue ain't gonna stick to the sides of these joists. I can shop vac them and sponge them down.

2. When bolting (bolt/nuts/washers) on sister's what should the distance b/w bolts be? I've heard an up and down pattern is best when bolting. Some bolts high and some low.

3. I'm going to sandwich the old joists with two 2"x8"x8's. Pic below shows the center on center of the old joists were all over the place. Ranging from 11" to 17 1/2".

4. How the heck would i get 20' joists in here if I wanted to replace them all? Through the windows I guess. I understand replacing the joists would be the ideal solution, but I cannot rip up the entire floor. The floor is flat for the most part, but off level in the center.