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CliffQ · 05-16-2008, 12:37 AM

I understand that "Exposure 1" panels are suitable for uses that are not permanently exposed to weather, if I cover the panels with ceramic tile, will that be enough to protect the panels from the weather?

Also, can I thinset/mortor the ceramic tiles to the panels or do I need to put down cement board first?

Thanks for any advice you can provide.

MacRoadie · 05-16-2008, 02:53 AM

I assume there's a waterproof membrane in there somewhere?

**thekctermite** · 05-16-2008, 09:05 AM

Here's the APA's take on this.

Exposure 1 Plywood Panels are suitable for uses not permanently exposed to weather. Panels classified as Exposure 1 are intended to resist the effects of moisture due to construction delays, or other conditions of similar severity. These panels are manufactured with the same fully waterproof glues as used in Exterior plywood; however, because of other compositional factors that may affect bond performance, only Exterior panels should be used for long-term exposure to weather. Exposure 1 panels may, however, be used where exposure to the outdoors is on the underside only, such as at roof overhangs.
APA Rated Sheathing Exposure 1 plywood, commonly called CDX, is oftentimes confused with an Exterior plywood panel and misused in applications. It is important to understand the difference between these classifications in order to select the best panel for your project.

Exposure 1 plywood has less voids, but the same glue. Otherwise the differences between it and rated sheathing are few.

You should not tile directly to the plywood!!!!! You must put down 1/2" tile backer. A waterproof membrane must be installed under the tile backer to prevent moisture from migrating to the plywood.

CliffQ · 05-16-2008, 01:10 PM

Thanks for the advice, I really appreciate it.
Is there any or much of a difference between 'exposure 1' OSB and 'exposure 1' plywood?

Any recommendations as to what waterproof membrane to use and what type of grout and sealer to use?

Thanks again for the advice.

**thekctermite** · 05-16-2008, 02:52 PM

I'd suggest plywood. I'd also suggest priming and painting all surfaces.

There's some good tile guys in the flooring forum that could give you a good suggestion for membrane and tile materials. You should post that question there.