Finishing Subfloor 1-1/4" Out of Level

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ian

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I'm currently stumped on a subfloor issue at bathtub, see attached photo.

The bathroom subfloor slopes up from the tub drain location to the opposite wall approximately 1-1/4" (wall with silver faced insulation in photo is the high point). The rest of the bathroom floor is fairly level & consistent with the tub drain location. I'm concerned with finishing floor tile if the tub is installed level.

I don't think I should shave the floor joist since they are only 2x8 and it is also difficult to work around the toilet location (basement below is finished). I don't think floor leveler around the tub will work given the thickness required and minimal run to bathroom door (this would result in a floor slope of 1/4" per foot which I assume would be noticeable to someone walking into the room... ??).

So my only other ideas are to install the tub slightly out of level from drain to opposite wall, not sure how much is too much?
Or
Install tile base at the tub apron to hide the gap but I'm concerned this would be noticeable?

Any other ideas or suggestions?

Thanks,

Ian

PS: I searched the Shower & Bathtub Forum and found similar issues but not quite anything leading to an aha moment. Apologies if I missed something.

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Danlar4470

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Personally, I would remove all the subflooring and see why that drain end has settled so badly. It sounds as if you don't really have a good structure to lay tile on without beefing up what you have. It may be possible to add 2x 8 nailers at level to the existing joists to start the leveling process, at the same time as adding some stiffness to the floor joist. Good luck
 

ian

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I removed a portion of the subfloor and can only assume the existing floor settled somewhat from the weight of the old cast iron tub. That and the fact the house is ~ 50 years old and the 2x8s are probably undersized by current standards. From everything I can access, it appears the slope is fairly isolated to this area.

It would not be easy to sister the full length of existing joists because of the amount of MEP stuff in the floor cavity. The bathroom is above the WH, furnace, electrical panel, and primary waste stack...

I bought some 8ft 2x8s yesterday and plan to shave, sister, & level the joists directly under the tub. I'm planning to leave the rest of the bathroom floor where it is because of accessibility issues. There will be a weird subfloor transition at the tub apron (i.e. subfloor under the tub will be higher than rest of bathroom floor) but I don't know what else to do.

Appreciate the comments, thanks.
 

John Gayewski

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I have in the past cut shims from 2x4s to level a floor. But when I did that I also remedied the cause of the sagging.
 

Jeff H Young

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Ian, Since you are approaching it the quick and dirty way I think you may be able to level the tub and put a rubber molding along the front depending on the new flooring you'll only be covering a 1/2 inch gap . so sistering up joists to stop the sagging and then leveling the tub put some mud under it . as long as you aren't concerned with structure being sound
 

wwhitney

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The low end of the joists, what do they bear on? Follow that down to the foundation, what does that look like?

If you have, e.g. rusty lally columns in the basement supporting a girder, then most likely the lally columns have rusted shorter, and/or their footings are undersized and have settled. In which case the girder should be jacked back into place and properly supported.

Cheers, Wayne
 

Jeff H Young

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Agree with John but when I'm on the job I'm not repairing structure , contractor , carpenter , or owner can handle it . I won't touch a structural issue like that I've done some framing but wouldn't be responsible for it
 

ian

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Thanks for the additional insight. I've attached some photos from the unfinished side of the basement.
The portion of subfloor removed in "basement1" picture is under the tub.
The "basement2" picture shows the opposite bearing point of the 2x8 joists (double 2x8 beam on steel posts).

If I shim the topside I can only go as far as the bathroom doorway which ends around the electrical panel. Beyond the bathroom is finished hardwood that I'd hate to start pulling.

I'm going to look into jacking the steel posts up. There are no diamonds or piers in the slab to indicate if these are even sitting on footers.

Jeff I think you're right the gap under tub might not be too unwieldy after floor tile to cover with something... hopefully I can find something a little better looking then a rubber base. Hate to call this the dirty way but I don't see many other practical solutions (except maybe jacking and shimming the steel post... to be continued).

PS: don't judge me on any of the janky MEP installations shown in the photos. I didn't install any of it but I'm slowly working on correcting.

basement2.jpg
basement1.jpg
 

wwhitney

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Looks like your "double 2x8" beam has the 2x8s flatwise? That's woefully inadequate, beams should almost always have the wide dimension upright, and even then a double 2x8 is probably too small. Are the joists continuous across that "beam" or are there separate joists on each side of the beam?

I suggest making a diagram of the joist size, grade/species (if you can guess), spacing, and each span length (exterior wall to girder to exterior wall). Plus using a laser level or the like to determine the relative elevations for a typical joist at each support point and each midspan.

Most likely the proper solution is to cut in new footings in the slab, install a new girder (could go under the existing flatwise 2x8s to minimize disruption, at the expense of less headroom under the girder), jack the girder up to level the joists, and then install new posts.

Cheers, Wayne
 

ian

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I misspoke, the beam/girder is actual two 2x10s, they are installed correctly on end.
The longer span of the 2x10 between posts is around 8ft.
The 2x8 joists have a 14ft span from bearing point, 16" OC.

Settling of the steel columns and/or 2x10s make sense since there are signs of movement on a wall directly above... i.e. drywall cracks at multiple spots.
 

wwhitney

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Zooming in on your photo, now the girder looks to me like (4 ?) 2x10s, with the 2x8 joists coming in flush on top. Which leaves a 2" strip of the girder below the joists, on which all that wiring was run.

Certainly sounds like the girder has settled. You can check the girder deflection between posts to determine if the girder is stiff enough. Then either the posts are rusting away at the bottom, or the footings are inadequate and have settled. The former is obviously easier to fix. If there's a concrete slab you can see if there are signs it has settled around the posts.

Cheers, Wayne
 

Terry

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Settling of the steel columns and/or 2x10s make sense since there are signs of movement on a wall directly above... i.e. drywall cracks at multiple spots.

I had a home in Redmond where the floors joining the stairwell can drifted downward. It was so bad that the doors downstairs would no longer latch, and if you dropped a ball in the kitchen it would roll out into the hallway.
When I looked in the crawl space, the expected concrete pads to support the stairway walls were mainly there, but nothing had been built using them. The main center beam in crawl also had nothing there.
I wound up hand pouring a large pad there, added structure to the stairway area, and proceeded to jack the house back up to level.

After doing that, the doors downstairs now latched, and yes, I had a bit of drywall repair to do in the living room. But the floors were now level and not going anyplace. I no longer have that place, I did like the views of Lake Sammamish there.

I stayed out Heavenly Valley for skiing two weeks ago. The place we stayed at had floors out of level. We kept leaning over and hitting walls while walking. It was easier skiing the slopes than it was walking in that place.

heavenly-2022-01.jpg
 
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