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Porcelain plank wood look tiles

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Mar 17, 2014, 08:50 PM
adoyt
Porcelain plank wood look tiles
Hi,

I want to install porcelain tiles / planks that look like wood. 12x24. My subfloor is 5/8 thick. Ive read that the floors need to be 5/8 at a minimum but 1 1/8 is recommended. Is that also the case for the porcelain planks? Also, I don't know how to decide between cement backer board or the ditra membrane.

Thank you!
Mar 17, 2014, 10:41 PM
JazMan
Hi,

Sounds like you've done a little researching and are on the right track. But you didn't supply much info about the subfloor or the framing it's sitting on. We always start the the framing and work up.

Need to know the; size of the joists, spacing and unsupported span to the inch. Try to figure out the species and grade too.

We know the subfloor is 5/8", I'll assume it's plywood, t&g glued and well fastened in excellent condition. Is that right? We'll start with that.

Jaz


Tile 4 You llc - Troy, MI
Kerdi shower specialist - Ditra installs - Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong!
Mar 20, 2014, 05:39 PM
adoyt
Thanks for your time. I can't tell the kind of material it is. I have a basement and the joists measure to be 14.5 inches apart and they are 2 x 9. The subfloor is in great condition but I am taking a wall down so I'll have to do some patching.

Teo
Mar 20, 2014, 07:21 PM
JazMan
Teo,

Why can't you tell if the subfloor is plywood or something else? If there's 14.5 inches space between the joists, that means the joists are the standard 16" on center. You didn't measure the span of the joists. Gotta know that too. Joists that measure 2x9" must be very old, or they're really 2x10" which 1.5 x 9.25". When was the house built and where is it?

It sounds like you're too busy to get us the answers right now, so when you have the opportunity answer back with the span and if possible the species and grade of the joists. There should be markings on every one if it wasn't trimmed off.

Jaz


Tile 4 You llc - Troy, MI
Kerdi shower specialist - Ditra installs - Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong!
Mar 20, 2014, 07:35 PM
adoyt
Hi,

No, I have time. I don't know how to tell if what kind of plywood - at the big box stores I see a lot of different kind of plywood. It is plywood / I can see the multiple layers. House was built in the 1980's and the joists are just over 9" so yes, they are 2x10. The joists span just over 13 feet.

Curious, why is the joist span important? I have one section I'd like to tile that extends "off the house" like a bow window but floor to ceiling (no joists under that area)
Mar 20, 2014, 09:08 PM
JazMan
Ok, so it's plywood after all. So the framing is 2x10 @ 16" oc and the span is 13' + something inches, and you don't know the species or grade. The subfloor is 5/8" ply. We'll have to assume it's t&g, (cuz it's the subfloor).

The framing; since I don't know the species or grade I would say you're at minimum specs at best. I think you should stiffen the joists. Either sister the joists or build a supporting wall to shorten the span.

After you stiffen the joists I agree it's best to add another layer of underlayment to stiffen the area between the joists. Make it as thick as possible, but 3/8 is the min. Then you can install a concrete backer board or a product such as Ditra.

Jaz


Tile 4 You llc - Troy, MI
Kerdi shower specialist - Ditra installs - Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong!
Mar 20, 2014, 10:49 PM
adoyt
Darn, I'm not prepared for that. The area I want to tile / the span already ends at a supporting wall.
Mar 20, 2014, 11:02 PM
JazMan
Not sure what you mean by the span comment. Make the span less, there's several way, or make the joists stiffer.

Jaz


Tile 4 You llc - Troy, MI
Kerdi shower specialist - Ditra installs - Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong!
Mar 20, 2014, 11:08 PM
adoyt
Its too big of a job to sister all the joists and if I created a 2nd supporting wall it would be 5 Ft from an existing supporting wall.
Mar 21, 2014, 10:22 AM
swschrad
if you lay half-inch cement board over the subfloor with mortar and screws, it should stabilize the floor enough to protect that tile. stagger the cement board so you don't have "four corners meeting" any place. Kerdi in mortar atop that will isolate the tile from the base for added protection against floor wobble, which is what cracks tile.

don't buy it, but look at one of the Hardie-type underlayments to see the checkerboard on top. what is that? where the lines cross, is where the screws go. that's basically how many screws have to drive through the cement board into the floor to d* sure stabilize it.

This message has been edited. Last edited by: swschrad,


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Mar 21, 2014, 01:53 PM
JazMan
Adoyt,

Depending on the layout you might just build a closet, shortening the span by 2 ft or so and that would be plenty. Others simply install a beam. Another solution is to sister the mid 2/3 of the span.

Swschard, Sorry, but I completely disagree with your suggestion to add concrete backer to stabilize the floor. Concrete backers add no structural strength. The floor has to meet certain standards for deflection before adding any CBU or membrane.

You also mentioned Kerdi to further help. I think you meant to say Ditra, not Kerdi. Well, they're both orange in color.

Jaz


Tile 4 You llc - Troy, MI
Kerdi shower specialist - Ditra installs - Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong!
Mar 24, 2014, 02:19 AM
ron45
For joists that are Unknown wood, but in good condition, 9.25 inches tall, 1.5 inches wide, 16 inches on center, and 13.5 feet long between supports, the deflection calculated is 0.509 inches.

This translates to a deflection of L / 318.

Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Sheet Vinyl or wood.

For joists that are Unknown wood, but in good condition, 9.25 inches tall, 1.5 inches wide, 16 inches on center, and 13 feet long between supports, the deflection calculated is 0.446 inches.

This translates to a deflection of L / 350.