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Do I need to replace part of my bathroom sub-floor?


mary.henderson's Avatar
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03-11-13, 08:15 AM   #1  
Do I need to replace part of my bathroom sub-floor?

I have a roughly 3x5 shower stall that was tile (walls and floor), built in the early '80's. Due to bulging wall tile where the wall met the tiled stall floor, I decided to tear out the shower and rebuild before the damage worsened. Along the way I have found many things wrong with the original construction, including problems with the sub-floor.

In the photos below you can see how the sub-floor is water-stained and peeling in some spots, and more alarmingly (to me, anyway) the mystery hole to the left of the drain that had been patched by the builders with a block of wood (shown in the photos).
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Am I right in thinking the sub-floor needs to be replaced before rebuilding a shower over it, or should I just throw that wooden block "patch" back in and start building over the peeling subfloor? If I need to replace it, how can I do just the sub-floor in the shower area, or do I need to replace the entire bathroom's sub-floor all at once?

 
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Pulpo's Avatar
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03-11-13, 10:27 AM   #2  
I don't see any reason to replace the entire floor. Hit the suspect places with a hammer. If it's solid, I would leave it.

 
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03-11-13, 02:59 PM   #3  
The little scab of plywood looks like it will be cantilevered a bit from the 2x cross-member under it (that you'll be nailing it to). You might want to beef things up underneath with additional framing, sistered (glued/screwed) against the piece that's there. If only to make you sleep better at night, knowing you made it better than the "professional" who was there before you.

 
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03-11-13, 05:08 PM   #4  
Good viewing and reading before you start your rebuild. How to build a shower - Building a shower pan with pre-sloped mortar bed, liner and curb.

 
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03-11-13, 05:20 PM   #5  
I saw that thread yesterday when I was lurking around, but thanks for sharing. It's extremely helpful! Aside from replacing the drain (if I determine I need to do that--the metal flange under what's left of the rubber liner is severely rusted, and I can't tell if there are any weep holes or not), I feel very confident that I can do a much better job rebuilding this than the original builders did, and probably almost as well (if not better) than a contractor. I'm so nervous that whoever I would hire would just do it wrong like the builders did, AND for way more than it would cost to do it myself. I appreciate all your responses which are encouraging me to just go for it!

 
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03-11-13, 09:14 PM   #6  
Paying good money for a marginal job is enough to make anyone nervous. Or even downright furious. Just remember when installing the pan and shower, that water will work its way into all kinds of places where it doesn't belong, if given the chance. I've replaced a few faulty shower systems that make yours look pristine (including a recent one with rotten, smelly wall studs all the way around). All were built by people in the trades, making (somewhat of) a living at it.

Take your time, do things logically, and if questions come up that you're unsure about, just come back here and ask away. Most of us are much happier sharing our knowledge than taking it to the grave with us.

 
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03-11-13, 09:29 PM   #7  
should I just throw that wooden block "patch" back in
I would. But before I did that, I would cut a piece of 1 X 3 3" or 4" longer than the block is wide, put some adhesive on each end and one side of one face, hold it under the near side of the opening a run a couple or three screws into it from the top. Not black drywall screws.

 
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03-12-13, 02:56 AM   #8  
I guess that someone needed to access the drain during the last build, thus the cut out. If it was me, I would replace the drain assembly and beef up the thickness of the floor. 1/2" is not enough subfloor for tile, even in this small area. If you are going to tile the rest of the bathroom floor, I would beef up the whole floor system. I would also add 2x10 blocking around the base of the walls in between the studs to help support the pan membrane.

 
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03-12-13, 06:43 AM   #9  
I just measured, and the sub-floor is 3/4". Is that beefy enough? I'm feeling fairly confident about the whole job--except replacing the drain. The one on there doesn't resemble any of the drain assemblies I've seen in videos. I see no bolts, so I'm not sure if it needs to be cut off or what. I should probably dig around on here and online in general and start a new thread on shower drains. Thanks for your input, everyone! Oh, and as Bridgeman45 pointed out, I need to remember that it could always be worse. I will remember that.

 
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