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02-06-2017, 06:12 PM

Thanks in advance to those who can help. We want to put ceramic/porcelain tile in an area appox 19x10 which is above our basement. After reading the posts and trying the calculator, I think we will be ok, but would like some feedback. The floor currently has a 5/8 OSB supported by 2x10 joists spaced 16inches apart, supported every 13 feet. The part I am not sure about with the calculator is the type of wood. The joists are stamped AFPA 167 / spf / s or 8 dry / 2. From what I can tell this is spruce,pine or fur grade 2 joists. The supporting beams perpendicular, above the beam with looks like a 4 x 10 supported by round steel beams.

Will this floor support tile and what size backing board would be recommended


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02-06-2017, 06:38 PM
Welcome, Erik. :)

If you had a geographic location in your User Profile we could more reasonably guess whether you had northern or southern SPF lumber there, but in either case I can find you a span calculator that says the joists at that span met building code (L/360) when built and that's generally acceptable for a ceramic tile installation.The supporting beams perpendicular, above the beam with looks like a 4 x 10 supported by round steel beams'Fraid I don't understand any of that and it might be important.

Your subflooring is the absolute minimum recommended by any manufacturer of tile substrate material and not acceptable to some. I'd very strongly recommend you add a second layer of nominal half-inch exterior glue plywood to what you've got. Here's a good article (http://www.johnbridge.com/images/mike2/For%20Liberry%20Stuff/Underlayment-Nielsen-Woeste-0604.pdf..pdf) from our Liberry showing what I consider the best method of installing that second layer. After that you can install the CBU or membrane of your choice as a tiling substrate.

My opinion; worth price charged.

02-06-2017, 07:23 PM
Hi thanks for responding.

I live in central Pennsylvania.

The 4 x 10 I mentioned...

The joist run north to south, they are supported every 13 feet by the 4 x 10 beams running west to east below them. The 4 x 10 beams are held up by round steel posts that are anchored to the foundation.

02-06-2017, 07:30 PM
If you don't put the geographic location in your User Profile the information will be lost before we leave this page.

If the posts are spaced adequately and properly supported that should be fine. Can't tell any of that from out here, though. Was the house built within a code compliance jurisdiction requiring inspections when built?

02-06-2017, 07:38 PM
I must not have saved it after I updated the profile. It should be there now.

Yes,code compliant and a coo was required. House was built in 1995

02-06-2017, 07:42 PM
Yep, there now.

If that's the case, your floor structure should meet the code requirement of L/360 deflection and that's sufficient for a ceramic tile installation in the eyes of the ceramic tile industry.

My opinion; worth price charged.