[brian85]

In an old (110 years) home I recently purchased I found that the 2x8 joists that have been severely compromised by a bathroom remodel done a few years ago (first picture with gouge on the top of the joist). A friend's suggestion was to run ("sister"?) a 2x4 along the bottom half of the 2x8. I don't think a 2x4 will fit above the PVC pipe, so I was also thinking of putting some 1" plywood - say maybe 2"x48" - along the top side of the joist to strengthen right where the gouge is. See my proposed diagram.
Further down on the same joist are 2 big pipes going through the center of the joist. The holes take up approximately 1/3 of the width of the board, as seen in the photo. Is this problematic? I have a clawfoot tub basically directly above, so the amount of load here will be very high.
Besides these place where significant portions of the joist have been carved out, is there any general reason to add supports? The same friend said that adding 2x8 blocks perpendicular to the joists is not helpful because, at this point, the joists don't sag any further than they've already sagged.
One idea I'd been mulling over was to run run 2x4s along the bottom sides of each joist and adjust them so that the bottoms of the 2x4s were level. I was thinking that this would both add strength and help with the drywall later. To be clear, the bottom of the joist and the 2x4 would be the same height at the bottom of the sag in the ceiling. Near the edges of the room, where the joists are not sagging at all, the 2x4s would be lower than the joists. Does that explanation make sense? See diagram.



All of this is preventive. Nothing is broken, just trying to make things strong while I have access to it and before anything might happen.

 

[Nealtw]

Best would be to cut the white add a new joist as long as you can and drill a how for the white pipe to go back in.

If it has a big sag i would jack it up slowly over a few days and then add the new joist, something like this.

 

[de-nagorg]

I agree that Neal has a great idea, remove the PVC, then add a sister, glue and screw together, then re-run the PVC.

And if you are still worried, triple it just because you can now.


ED

 

[brian85]

Best would be to cut the white add a new joist as long as you can and drill a how for the white pipe to go back in.
If it has a big sag i would jack it up slowly over a few days and then add the new joist, something like this.

Thanks Nealtw! How do you feel about the general need (or lack thereof) to support the uncompromised joists?

 

[Nealtw]

Thanks Nealtw! How do you feel about the general need (or lack thereof) to support the uncompromised joists?

What are your plans for the bathroom. What is the floor now? will you be replacing it. How perfect do you want it or need it to be ?

It the floor bouncy now? how bad is the sag?

 

[brian85]

What are your plans for the bathroom. What is the floor now? will you be replacing it. How perfect do you want it or need it to be ?

It the floor bouncy now? how bad is the sag?

We don't have any plans to change the flooring upstairs. I'm not great at judging how bad the sag is, but I'd say that I just notice it in one place upstairs. We don't need it to be perfect by any stretch of the imagination - but I would like to feel that it's solid structurally. Which is part of the reason I liked the idea of running the 2x4s along the bottomside of the joists: adds strength and makes the drywall easier.

 

[Nealtw]

We don't have any plans to change the flooring upstairs. I'm not great at judging how bad the sag is, but I'd say that I just notice it in one place upstairs. We don't need it to be perfect by any stretch of the imagination - but I would like to feel that it's solid structurally. Which is part of the reason I liked the idea of running the 2x4s along the bottomside of the joists: adds strength and makes the drywall easier.

If you have a tile floor now and it stays you don't want to move the floor much?

 

[brian85]

If you have a tile floor now and it stays you don't want to move the floor much?

the bathroom floor seems like it was redone at the same time they hacked into the joist. The visible surface is these 1 square foot flexible tiles that might be glued down. One of them is loose and that's how I know they're flexible.

 

[Nealtw]

the bathroom floor seems like it was redone at the same time they hacked into the joist. The visible surface is these 1 square foot flexible tiles that might be glued down. One of them is loose and that's how I know they're flexible.

I would like to know what the sag is, the easiest is a laser level

Something like this Bosch is really handy for working in the house.

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[JayDoesIt]

It looks to me like your dip is probably right in the area of the pipe cut out and the 2x4 on the bottom might help a little with the bounce but its not going to fix the dip at all.

I ran into this same issue only a little worse because they cut 6 joist like your first one with the pvc ran through it, So I ended up moving the kitchen, adding a 1/2 bath removing all the old plumbing ran across the floor joist. Added a new sister joist to every one that was cut, and used the wall cavity from the added 1/2 bathroom to bring the plumbing up from the basement through 1/2 bathroom wall cavity.

In your case I'd skip the 2x4 idea it's just not optimal imo. I'd cut the pvc like nealtw stated and I would sister the joist and then use a hole saw blade to drill the hole for the pipe and then I would add a metal sleeve bracket. The other 2 although not ideal aren't so bad. You could probably do 2x4 on top and bottom of the others to spread the load across the notches they made for the other pipes.