quarry on a porch [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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06-18-2001, 09:05 PM
in the middle of the project, i find out i've done it wrong! now i could use some help figuring out the best way to proceed.

applying 7x7 quarry tile floor on a screened (and fairly protected) decked porch in the midwest. i have 2x6's 1'-0" on centers under the existing tongue-in-groove decking. i've topped that with 3/4 osb (tongue-in-groove) screwed through to joists. i was going to apply thinset and tile directly to osb but see the specifications on thinset say it will fail.

elevation is so high at this point, there is no room for even 1/4" concrete backer board. therefore, i need an application to put on the osb that will accept thinset, i.e., epoxy or something along these lines.

i'll stall a day waiting for respones, but vacation time is running out!

thanks in advance.


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06-18-2001, 09:30 PM
OSB when exposed to moisture continually expands. This expansion will cause your tile to pop. Tile doesn't move well. You can waterproof the top layer, but what about underneath, moisture will get to it.

Tear out the OSB and wait for one of the tile contractors to help you with the 2x6's over 1 ft on centers. I think you will need to shore it up, but these guys do it for a living, I just sell the setting materials.

Cement backer board is no doubt the best way to go, all though you may have some other recomendations thrown at you.

My guess is if you want your investment to last, you may be working on this on your next vacation as well. And make sure your Brother in law is as savy as you, and knows how to find the answers to his questions, like you. Because no doubt he will want to try his hand at finnishing this job when he comes up on vacation.

Where is this project anyway?

I'm an old midwest boy (boy? don't I wish!) I lived in Michigan 48 years (now every one knows how old I am)and will be back, the week of the 4th of July.

Good luck and don't do something just to get it done, it will come back to haunt you, and then you will have to listen to your brother in law the rest of your life.

Rob Z
06-18-2001, 11:16 PM

Thanks for visiting the Forum. Art is correct with advice to remove the OSB. Dimensional lumber itself isn't acceptable for tile, either. (An exception would be as a substrate for thick bed mortar inside a house)

I'd start with Peter Nielsen at Schluter (www.schluter.com) to see which of their exterior products might be suitable for your job.

Laticrete also makes products for exterior tile installations (www.laticrete.com).

I suspect with your height restrictions you will have a hard time getting one of their products to fit.

Please let us know what you find out.


John Bridge
06-19-2001, 06:22 AM
Hi Jeff, Thanks for stopping in.

I hope Art and Rob have convinced you of the magnitude of your screw-up, and I hope you won't try to continue the project withough major reconstruction.

The framing can probably be shored up by adding a few additional pieces, but the osb definitely has to go. If you only have room for one layer of material over the planks, I would use cement backer board.

Whatever you do, the subfloor will have to be waterproofed before any tile can be installed.

We're here to help you complete a lasting installation.


06-19-2001, 07:03 AM
Water-proof BOTH sides.Moisture from underneath can be just as damageing to the structural integrity of the subfloor as rain.

Bud Cline
06-19-2001, 08:50 AM
Echoing all the others. The OSB is not suitable for the use you specify, it should be removed.

Bud Cline
06-19-2001, 12:17 PM
Hey Jeff,

I just completed a tour of my usual stops around the net and your everywhere. How could you find all those specific boards so quick? The amazing thing is you have gotten responses to the same question from about twenty-five different professionals now. They are all the same answer with little to no variartion. So now what are you gonna do?

Also where did you get 7" X 7" quarry tile?

Rob Z
06-19-2001, 08:03 PM

Frequently, I find that these wacky sized tiles are really metric in dimension.

Rob "Mr. SAE" Zschoche

Bud Cline
06-19-2001, 08:25 PM
Just curious. I've done a lot of quarry over the years but it's always been 5-3/4 to 6 inches. So many things are changing now-a-days I was wondering if quarry was changing also.