New subfloor and ceramic tile for 3rd fl. bathroom


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Old 08-11-09, 02:25 PM
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New subfloor and ceramic tile for 3rd fl. bathroom

Hi,

Thanks to everyone's help on this forum we now have a beautiful new porcelain tile floor in our kitchen!

Next we want to convert a small room (7x11) on the third floor into a bathroom, with a ceramic tile floor. The house is 100 years old. The joists aren't all the same size or spacing but are on average 8.0"x2.5", 18" O.C. (minor notching in joists for supply pipes but nothing too serious.) The existing floor is 3/4" thick hardwood planks (Georgia pine maybe?) directly across the joists and that's it.

We're considering removing the existing floor to try to reuse some of the hardwood to fix the dining room floor. (Also from what I read here, hardwood planks are not the best subfloor for tile). Here's my question: Since I probably won't be able to remove the current hardwood floor all the way to the edges of the room, I'll have to put down a 3/4" subfloor to match the height. What's the best way to do this? Should I put down a 3/4" plywood subfloor onto the joists, and then 1/4" hardibacker and then tile? Or something else?

Thanks as always.
 
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Old 08-11-09, 03:13 PM
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Hi!

If you didn't want to take out the planks, you could screw at layer of at least 1/2" ply onto the top, then backer board and tile.

You can patch the floor with ply if you choose to remove some planks to fix other areas. You might have to add blocking between the joists to support the new patch first though. You can use a toe kick saw to cut flush with the wall.
 
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Old 08-12-09, 07:50 AM
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Thanks OKC. I'm leaning toward removing the entire floor down to the joists so that we'll have all the hardwood for future use downstairs. So, does my plan sound reasonable:

3/4" plywood subfloor screwed to the joists
1/4" hardibacker screwed to the subfloor with thinset in between
porcelain tile on the hardibacker

If this sounds ok, do I need a special type of plywood for the subfloor, or is any 3/4" plywood ok?
 
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Old 08-12-09, 01:41 PM
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Your plan sounds good. If you got a HD near you, I believe they have Advantec plywood, which is good. You should get a AC or BC rated exterior glued (NOT pressure treated) plywood. AC basically means one side (the A) has no knots and nice and smooth, while the other side (C) is a little more rough. The plywood will be about $25+ a sheet. I would recommend glue the ply to the joists as well. This seems to minimize any squeking later on.
 
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Old 10-06-09, 07:49 AM
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Thanks OKC. We got the 23/32" T&G subflooring over the weekend. Couple of questions regarding installing the subfloor:

1) I see can why gluing the subfloor to the joists is good, but how would we ever remove the subfloor in the future if we needed to for some reason?

2) Are 1 5/8" deck screws ok for screwing the subfloor to the joists?

3) Should we leave 1/8" or so between the old hardwood subfloor and the new subfloor panels, or should everything meet up flush?

Thanks as always.
 
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Old 10-06-09, 10:50 AM
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1. Hopefully you don't ever need too. That subfloor should outlast you....

2. I would go at least 2".

3. I'de leave a 1/8" gap, but that's your call. There's been debates on whether or not to leave a gap for the subfloor panels in the field.
 
 

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