Replacing bathroom subflooring-Joist problem


Old 04-19-18, 01:12 PM
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Replacing bathroom subflooring-Joist problem


I’m planning on retiling a 4’3” x 4’11” area in an upstairs small bathroom in a 1936 house. The toilet leaked and water came through the ceiling in the kitchen. The old ceramic tile was installed directly to 1/4” plywood screwed and glued onto square edge sawn 3/4” inch planks that are 7-1/2" inches wide. Since it didn't seem possible to just remove the plywood, I decided to remove all of the sublooring where the tile is to be installed in hopes of better foundation for the new tile, as well as minimize transition issues to the wood flooring. The current subflooring is about flush with the wood flooring. I’ve cut out the water damaged portion of the plywood and planks so far. The joists underneath are 2"x 7-1/2” x 7'2" (actual sized) and 16” OC. The length only runs under the bathroom.

Problem: In my lack of wisdom, I was assuming a joist would be located directly under the doorway, thus allowing me to remove the all of the sublooring in the entire area to be tiled. Now, I'm not so sure. I haven't cut through the planks yet in this last section. Please see attached pictures and the 16 inch mark on the tape measure. If I cut through, I'm not sure I would have sufficient working room access to add blocking etc. to support? If I need to leave it, can I match it sufficiently with new subflooring to have a sound tile job? I'm hoping to install 1 inch hex tiles. Please advise on how you think is the best way to proceed.

Thanks in advance for your help. I sure need it.

Last edited by XSleeper; 04-19-18 at 03:33 PM. Reason: Added link
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Old 04-19-18, 01:30 PM
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I would probably remove just the 1/4" plywood on that last bit. IMO you should be replacing the 1/4" plywood with cement board that is set in thinset and screwed down. Sister your last joist... glue and screw together so that your new plywood has something solid to land on.

Does that help? Others will be along so they may have more to add.
Old 04-19-18, 01:44 PM
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Thanks for the quick reply XSleeper. I was contemplating that. Was worried 1) That because glued and screwed, planks underneath probably get pretty torn up trying to separate. 2) That I wouldn’t have proper thickness of underlayment. Planks only 3/4 inch thick. Maybe the small mosaics would be more forgiving and less likely to crack?
Old 04-19-18, 02:23 PM
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Small mosaics on a imperfect floor are "More" likely to crack as it is mostly grout which will flex if the floor moves.

Your pictures didn't take. Click on reply, then go to advanced, look for the picture icon and browse your computer for your pic. Then hit upload. Pictures need to be down sized for upload to the web. Lots of free programs to do this for you.

If I understand correctly, your concerns are where the joists run parallel to the wall and removing the floor will leave nothing for support. In these situations, you need to add cross blocking that is toenailed into the next joist under the wall and provides a nailing surface for your new subfloor. Most likely involves removing portions of your plank subfloor.
Old 04-19-18, 03:22 PM
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Thanks Czizzi. Yep that is my concern. I'd be happy to do the appropriate blocking, just not sure will have the space to do it without pulling up wood floor or taking out a big portion of the kitchen ceiling.

Sorry about pic, just have access to my phone right now, and I'm a Luddite. In my original post at the bottom, I did a Google photos link that I think if you cut and paste should work. It's only one pic I can add later of helpful.

Appreciate the advice. Nice of you guys to take the time.

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