Bathroom sub-floor

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  #1  
Old 01-01-15, 06:10 PM
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Bathroom sub-floor

I am in the middle of a second floor 3-fixture bathroom renovation. I have a few questions regarding the sub-floor. Hopefully the attached photos can be seen.

Photo #1 – around the toilet flange
I have a plumber scheduled to replace the toilet flange and he has asked that the sub-floor be removed around the flange. The yellow lines on the photo are the approximate location of the floor joists underneath. The red rectangle represents the area that will be removed. I can attach the new sub-floor piece to two of the floor joists, but the area against the wall is a concern since the cut along the toe plate will be a few inches from the floor joist. That section of sub-floor will be “cantilevered” approximately 8 inches. I am installing a 1/2 plywood underlayment on top of this sub-floor before installing the tile. Any ideas how to block/frame this area?

Photo #2 – near the shower
As can be seen in the photo there is extensive staining in this area from leaking water over the years. The sub-floor appears to be in good shape structurally (no mold or dry-rot). Should I seal or paint this area before installing the new shower pan, underlayment, tile? If so, what are the recommended products?

Thanks

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  #2  
Old 01-01-15, 06:28 PM
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Which way does the pipe run for the toilet? How much room do you have above the pipe to put any blocking in? Why does he want that entire area if just the closet flange will be replaced? The closet flange should be set on top of the finished floor. Is he installing the flange on his first visit?
 
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Old 01-02-15, 07:10 AM
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I'm with drooplug on this one.
How would you install the new subfloor and underlayment if there's a flange in the way?
He should be roughing in the plumbing and leaving a tail piece sticking up so you can drop the new flooring in place straight down then install the flange.
How thick is that subflooring?
 
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Old 01-02-15, 07:27 AM
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Thanks for the follow-ups guys. The drain pipe for the toilet is somewhat strange. The old flange connected into a “T” and the pipe goes to the left and right (see updated photo, in white). To the left it links up with a vented main stack, to the right it connects to another drain. I needed to cut off the existing flange to remove the underlayment, also the flange was in bad shape. The plumber will cut the drain pipe back and put in a new “T”, then I can put in the new flange after installing the new sub-floor, underlayment, ditra, and tile.

It doesn’t look like there is allot of room between the sub-floor and the top of the drain, but if there is enough room I plan to run some 2x4 blocking top to bottom.

The existing sub-floor is ˝ plywood, I plan to install a ˝ plywood underlayment on top of the sub-floor.
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  #5  
Old 01-02-15, 08:03 AM
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What is the pipe made out of? Why do you need a new T? They make several types of flanges to connect with existing plumbing.

I'm sure you want to avoid this, but it might be better to get at it from downstairs.

I'm still new to tile myself, but I think you will want to lay 3/4" plywood over what you have now. Make sure you get stuff made for flooring and not sheathing. It is stiffer.
 
  #6  
Old 01-02-15, 08:06 AM
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I'm not sure this will be adequate to support tile, but I am thinking you use PL and screws to attach a 2x6 laying flat along that seam. Then screw and PL your patch to that. Ideally you would connect to that other joist, but that may not be possible.
 
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Old 01-03-15, 06:11 AM
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Use joist hangers to give you something to get blocking under that back wall to the joist in the next room. Use a palm nailer to hang and shims to get it to the right, tight level. Hopefully, you have at least enough room to get a 2x6 in and notched over the drain pipe. Then shoot a couple of nails through the first joist and into the end of the blocking.

Rot the subfloor, optimally, you will want a minimum 3/4" and more optimally an additional 1/2" on top prior to your ditra. Plan your floor height from the joists to bottom of the flange for a tight fit. Add some blocking around the flange so you have surfaces for the subfloor to sit. Install subfloor to get under the flange by splitting the piece to be installed 90 degrees to the joists and right down the center of the hole created for the flange. Slide the two pieces in from each side, hoping that you have a little play in the pipes to lift the flange slightly. Then screw the flange down to the subfloor.

Regarding the shower, which is now a jetted tub apparantly, you will need to update the drain line to 2" if you are putting in a standing shower only. The 1 1/2" that is currently there is not to code.
 
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Old 01-06-15, 06:11 AM
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All, Thanks again for the follow up information.
Drooplug, I had initially considered getting to it from underneath, but reconsidered after your post. I think that is the way to go and avoid cutting out the subfloor. A little ceiling drywall work in the bathroom underneath seems easier. The subfloor is stained from previous overflows, but it looks to be in good shape structurally. The current T/flange is roughed-in for 10inches and it looks like that can not be changed easily. I will probably leave it at 10inches and find a toilet to accommodate.

Any thoughts on painting or sealing the subfloor before I install the new underlayment and tile? Kilns paint? Would this have any benefit?
 
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Old 01-06-15, 06:27 AM
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Painting the subfloor will do nothing other than steal a couple of minutes of your time that you can not get back. The only time that is recommended is if your dog or cat decided that revealing themselves inside was the in thing to do.
 
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