I need some advice on how to best address a sagging floor joist. The hot water heater leaked and saturated the joist prior to me buying the house. The floor sags about 1/4" to 3/8". I placed two adjustable jack posts underneath with a 4x4 piece of lumber spanning about 6 feet (see photo). I'm putting the house on the market in a month or so, and want to be sure this isn't something the home inspector pings me on. Due to all the plumbing, sistering up the entire length with another 2x8x14 doesn't seem like a viable option, if I could even get one down the access hole (doesn't look like it). As an alternative, I was thinking of attaching a couple shorter lengths to the side of the joist where I can, then screwing/nailing/strapping the jack posts directly to the underside of the joists in the areas I was able to double them up. Would this be worth the effort, or should I leave it as is? Or should I really try to get a full length 2x8 squeezed in there somehow? I could remove a foundation vent if I really had to in order to get the joist down into the crawlspace, but getting it into position would be tricky. It appears there is just enough clearance to sister up the joist with a second 2x8, but because of the plumbing, I'd have to slide it in from the opposite side of the beam and pound the crap out of it with a sledge to get it into place. The 2x8 would have to be vertical from the get-go because of how close the plumbing is to the existing joist. By the way, the side that I would do this from is opposite of what is shown in the image. What do you guys think? Would it be possible to position the board vertical and pound it from the opposite side? Maybe some kind of lube would help, like the kind electricians use for pulling cable?

 

If your inspector is at all on the ball, yes he will make a note that adjustable post jacks are being used in place of a permanent column... with no footing.

Hard to say what an alternative solution would be, but to keep the work to a minimum they should be approved for use as permanent columns (they look like they are but you can check), be on a concrete footing, and be non adjustable.

 

Sounds like I should try sistering then and remove the posts altogether. It was never meant to be a permanent solution. Is lubing the new joist up with cable lube to aid in sliding/pounding it in place a ridiculous idea? And if I need to cut out a foundation vent to get the joist down there, are they relatively simple to replace? The existing vents are metal and appear to have been cast in place when the foundation wall was built (cinder block).

 

It helps to rip a 5 degree bevel off the top edge of the joist to ease the edge that has to roll as you pound it vertical. Selecting one that is slightly crowned will "prestress" the joist and will actually be stronger than using one that is straight.

 

Okay, but my concern is how best to tap (likely pound) the joist in place once it is vertical. Because of the pipes, I have no choice but to slide the joist in place lengthwise--all 14 feet. IOW, tap the new joist vertical against the end of the sagging joist from the opposite side of the beam, then force it into place by pounding on it until it slides 14 feet. You follow?

 

Yeah that's not going to work unless it's narrower than the one next to it.

IMO you would be better off cutting the pipes and replacing them after it's in.

 

Oh man, sucks to hear that. Here's a diagram that I just did. Figured I'd post it since I took the effort. Red joist is the sagging one, orange is new, green circles are pipes that run vertical through the subfloor about 2" away from the sagging joist, gray box on the left is the foundation ball, red down the center is the steel girder.

 

Maybe I'll get lucky and be able to sister it up from the near side of the photo. There is only one pipe on that side that goes to the bathtub drain and I have a little wiggle room. Maybe I could snake around the new joist. Except I'd have to put a hard 90 degree elbow coming out of the drain. Actually, I may be able to reconfigure the drain so it drains to the back just below the overflow. As-is, the overflow connects beneath the drain, then straight down from the drain. Either way is acceptable right? I'll have to check again and see if this is doable.

 

Top diagram is the existing configuration and bottom is the proposed. There may be just enough room to make this work. I need to replace the drain plumbing anyway because it is leaking (notice the water puddle in the photo).

 

Why don't you put the 2x8 sister joist on the other side of the floor joist with 1/2" plywood sandwiched between the two? Granted the one end won't be resting on a beam, but with a few 3/8" bolts anchoring the two joist together, it should be enough to eliminate the sag.

 

Not quite following you. What is the purpose of the plywood and which end of the joist would be supported? I don' see how this solves the issue with the pipes being in the way. The more I think if it the more obvious it is becoming that I simply need to cut the pipes, sister the joist, then patch the pipes.

 

Does it make a difference if I put the top in first then hammer the bottom together? Seems like it would be easier this way because I could get a better swing with the hammer without hitting the adjacent joist on my backswing. Seems like I'm there would be less friction as well because the new joist would only be sliding against the block wall and the steel beam as opposed to the entire length against the subfloor.

I understand what you're saying about the crown, but that would make it that much more difficult to get the joist in place. Plus everything has settled in its current position over the past 15+ years, so I don't want to prop the floor up too much. As-is (with jackposts in place) the floor is pretty level. Not perfect, but good enough. If everything stays in place after I sister the joist and remove the jacks, then I'll be happy

 

I suppose putting the bottom edge together and pounding the top makes more sense because of the angle and how I would be hitting it. I'll remove the tub drain and give it a shot. Next weekend likely.

 

I think MS is suggesting the plywood to provide additional support, something along the lines of a "fitch plate". If you go that route, I'd suggest you apply plenty of liquid nails or construction glue to both sides of the plywood.

Although using 2x8's for a 14' span may meet code it's stretching limitations a bit, especially under a bathtub. It's kind of hard to tell from the photo but my first inclination would be to remove the pipes to make it easier to work in there and then replace them.

 

Sorry for the confusion. This is what I meant.



The inside end of the added 2x8 doesn't rest on the center beam,, but you are simply trying to take the sag out of the sistered joint.

And what Cdguy said is correct. The plywood acts as additional support.

 

I see. Or I could remove the interfering joist and place a new one on the opposite side so I could sister the entire span and rest on the beam. I may need to add another joist on the right side to maintain 16" O.C. though. Not a big deal. I think I have enough to move forward. Thanks fellas!

 

I was mistaken about the plumbing configuration. The pipe for the drain is directly below the overflow as shown in my first diagram. If it's okay to move the drain pipe directly underneath the tub drain, then I will have plenty of clearance for a new joist. I could put two new joists so the outermost one has bearing on both the block wall and the beam. Sound like a plan?

 

Depends on what arrangement you have for the stopper. A standard stopper with the lever in the overflow needs a straight drop to the drain tee to allow the stopper to block the tee. If you have a "lift and turn" or just a drain plug then you would not have a problem.

However I think the idea of sistering on the opposite side from the pipes is better. Add blocking (or a full joist that will not rest on the center beam) and then another against that supported on both ends. ( A triple sandwich.)

 

I see. I just have a regular drain plug, so no worries there.

I'm assuming you mean on the right side (near side of photo). Sorry, I forgot to draw the tub drain. It is on the right side, and there are two other pipes on the left side that are about an inch from the sagging joists. Sistering on that side doesn't appear to be an option. So, I'll be adding blocking on the right side, then a full length joist screwed into the blocking--triple sandwich..

FYI, the image in Post #17 is a sample image I found online. It is not my home. I posted it to show the drain configuration I'd have to use. I apologize if this caused any confusion.

Plan on using these screws: https://www.homedepot.com/p/GRK-Fast...2225/203525067