Ceramic Tile On Deck

ksmith13

I am a post frame barn builder, however i am building a sun room/office for my self. I have 2x8x14 joist on 16" centers with 5/4 board on top of that. Since I have decided to make part of the room an office, what is the best way to install tile over what I have down? Should I put durock down and then lay the tile, or can someone point me in a better direction.

Thanks in advance
Keith

Jordy3738

Either dura rock or another layer of plywood.

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TileArt

Hey Keith,

The first thing you need to be concerned with is the deflection ratio of your particular floor - how much it bounces. Adding sheet goods of any type will add no significant durability as far as your deflection is concerned. This is mainly a factor of your joists. With what you've described your deflection ratio is around 200. The minimum allowable for ceramic tile is 360 and for natural stone is 720.
The easiest way to achieve that is to cut your supported joist length in half which will take your deflection ratio to 1100 - good for either. That will prevent any movement in your floor ensuring your tile installation will last.
The minimum thickness of your subfloor above your joists is 1 3/8 so just add plywood or whatever you need to get to that width. If you decide to use durock or another backerboard make sure you use thinset beneath the backerboard to ensure all voids are filled. You may want to take a look at ditra for your subfloor if it fits your budget.

Hope that helps.

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Roger Northern Colorado Tile and Stone Contractor
_____________________________Fort Collins, Colorado
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JazMan

Yes Jordy, you must have misunderstood the question or conditions?

That deck isn't suitable for tile for sure. Either build a wall under it or sister the joist. Then I recommend installing a layer of 3/4" subfloor grade plywood, then cement backer, topped by Ditra if you can. Thinner plywood may not work since the decking boards are 5/4 and of course not t&g.

Jaz

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TileArt

Nevermind, Jaz beat me to it.

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Roger Northern Colorado Tile and Stone Contractor
_____________________________Fort Collins, Colorado
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Bud Cline

Is the 5/4 decking of a t&g nature or not?
What are the joist spans?

HS345

Bud,
The OP stated the joists are 2x8x14, I assume that means 14' spans. He also said the decking is 5/4 board, I assume that's regular ole 5/4 decking material.

But, you know what happens when we assume.

ksmith13

It has been a few weeks since the original deck was framed so I had to crawl under and do some measuring. The joist are indeed 2x8 spanning 14' however they are actually 2' on center. There is one row of 2x8 bridging in the middle of them and there is a short 4x4 post sitting on a 2x8x12" or so block nailed to ever other joist in the middle of the span. The decking is plain old 5/4 treated. My origianl plan was to put down two layers of 30# felt running in opposite directions before i put down what ever I had to put under my tile. I am a little worried about all the grief i could be subjecting myself to by putting tile down. Do you think I would be better off to put the felt, then 1/4 in laun then just use linolium? I want something that is easy to clean because the only access is going to be thru the sun room/porch which is built the same way, and I may decide to do the floor in it in the future.

cleveman

You are overspanning by 2'. Put a set of bridging in the middle and you'll be ok.

ksmith13

So i need to have bridging every 3.5 feet?

cleveman

You are spanning 14'. Put the bridging in the middle at 7'. screw it into the floor joists or use ring shanked nails. Put your tilebacker down and go to town.

ksmith13

cool that is what I already have, a row of 2x8 bridging in the middle of the span

Bud Cline

Now THERE is some really bad advice when it comes to installing ceramic tile. R-E-A-L-L-Y B-A-D!

Remember...this is the Internet. People can be anything they want to be here. That doesn't mean they know what they are talking about. Including me.

TileArt

Hey Keith,

"Bridging" will do nothing to increase your deflection rating. You can cut your joist span in half and that will do it but it needs to be done with a supported cross member. You need to have complete support beneath your joists on each end of a span. This is the only way to increase your deflection ratio enough for tile.

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Roger Northern Colorado Tile and Stone Contractor
_____________________________Fort Collins, Colorado
Tile Help Blog | Facebook | Twitter

ksmith13

Do you think I will be ok with Felt paper, 1/4" Lauan Plywood and then either peel and stick 12"x12", 18"x18" or sheet vinyl linolium?

TileArt

Sure, with any of those products you don't need to worry about deflection at all. If you can walk on it you can use those products. (Well, you know, with proper prep . . .)

__________________
Roger Northern Colorado Tile and Stone Contractor
_____________________________Fort Collins, Colorado
Tile Help Blog | Facebook | Twitter