The key is water management. 1/4" per foot slope is recommened. Choose exterior grade tile and thinset. A solid base covered with a membrane.

Chech out Laticrete,Schluter,Noble for drawings.

BTW, what state? Freeze/ thaw?

 

Michigan. Repeated freeze/thaw in a never-ending cycle. Keeps the soft people out

So a regular plywood subfloor with cement or HardieBoard and a membrane is sufficient substrate?

 

I don't use Hardibacker very often. According to the Hardi installation manual(which you should read), they give no warranty for exterior applications for HZ 5, Northern areas like Michigan. A membrane over the backer is required. Providing the framing and subfloor can support the tile weight, it is possible.

I prefer a 2 " cement base with Noble.

But, most tile membranes only have a ten year warranty.

Note; Hardibacker 500 is required by manufacturer.

 

Hardie board isn't for exterior applications. I believe Durock and Permabase both are rated for exterior.

TCNA doesn't have any specifications for the application as you're thinking of approaching it. The closest thing I see in in the guide would be to apply ply then a roofing membrane then mortar bed, with or without an additional membrane.

That seems like overkill for your situation but it may be allowing for the much higher changes in temp from a very sunny day, which could hit 150 degree surface temp, to -40 degrees.

I'd feel comfortable using a exterior glue plywood built up to the appropriate deflection and then NobleSeal with the seams sealed.

I don't think the CBU really adds anything but height if you're using a membrane.

 

Hardie board isn't for exterior applications.

*Hardi says it can be used but only warranties warm climate applications. And Hardi 500 is different than regular panels. Personally, I dislike the dusty, dry surface of Hardi for tile applications. And wetting it before tiling? Did you wet it too much or not enough? Did you clean it enough or not enough? :sad:



TCNA doesn't have any specifications for the application as you're thinking of approaching it. The closest thing I see in in the guide would be to apply ply then a roofing membrane then mortar bed, with or without an additional membrane.

*The plywood would need to be pitched so water could move under the bed to the outside edge. A subsurface membrane between the roofing membrane and mortar bed is important IMO. Better drainage if water gets in somehow.

A sheet membrane on top of the cement bed is considered the secondary waterproofing but I feel is necessary. Sheet membranes are the best compared to liquids. Noble is my preference :thumbsup:

That seems like overkill for your situation but it may be allowing for the much higher changes in temp from a very sunny day, which could hit 150 degree surface temp, to -40 degrees.

* I think the cement bed heats/cools at a slower rate versus plywood so the membrane stays intact better.

I'd feel comfortable using a exterior glue plywood built up to the appropriate deflection and then NobleSeal with the seams sealed

I don't think the CBU really adds anything but height if you're using a membrane.

My 2 cents.

 

Here's a link to Noble Deck over plywood specs:

http://www.noblecompany.com/Products/SheetMembranes/tabid/58/Default.aspx#products


:thumbsup:

 

Here is a screened in porch I built with a 12"x12" tile floor on the 1st and second floor. The first floor the tile was laid directly to the concrete slab, and on the second floor it is 3/4" PT plywood with 1/2" durock.

 

3/4" Ply and 1/2" Durock eh? :detective:

 

I'm surprised no one mentioned epoxy grout and depending on what type of tile , a sealer would also help to keep water from penetrating the surface .

 

Epoxy grout has very stringent installation requirements with respect to humidity and temperature swings..... In an outdoor application it would be difficult to ensure the manufacturer's installation requirements....

On the particular job I posted pictures of there was multiple applications of sealer, 1" of fall from the house to the outside, and a 3' roof overhang. The overhang keeps almost all of the water out.

 

Epoxy grout has very stringent installation requirements with respect to humidity and temperature swings..... In an outdoor application it would be difficult to ensure the manufacturer's installation requirements....

On the particular job I posted pictures of there was multiple applications of sealer, 1" of fall from the house to the outside, and a 3' roof overhang. The overhang keeps almost all of the water out.

I used spectralock pro epoxy grout on an exterior install I did about 5 years ago. Still looks good. I'm in Ontario…..temperatures range from -20 to 45 C.

 

Epoxy used to be the standard for exterior grouting but isn't UV stable. Now, high cement content, Fusion Pro and urethanes grouts have replaced it.

 

Doing this installation tomorrow. After reading all of your excellent posts and opinions, I think we're going to first re-enforce the porch framing, then do a layer of 1" plywood followed by 1/2" durock. We'll make sure we have exterior grade mortar and grout. That ought to be rock solid by the time we're done.

I made the serious error of attempting epoxy grout a couple years ago before I knew what a pain in the butt it could be for a newer tile guy; no mas!

We're also replacing the support posts for the porch. I was going to put down the subfloor, then put the posts in and put the durock around the posts. Any problem with that? I was maybe thinking that the posts would allow water to flow down into the durock?

 

As long as no water contact, mrcharles's way of doing is fine, but if the water (rain) goes on the tiles and then freezes, you will have a new project coming up.
I am assuming no living space under,if there is,it is an other animal.

 

As long as no water contact, mrcharles's way of doing is fine, but if the water (rain) goes on the tiles and then freezes, you will have a new project coming up.

:thumbsup:

 

Waterproof or you'll be back.

 

You mean sealing the grout? Because we always seal the grout, of course.

And the porch is covered, so we can expect a minimum (although not zero) water exposure.

And, at your advice, we will be pitching the subfloor 1/4" for every foot to allow drainage.

 

you know sealer isn't waterproof, right? I mean waterproof like Noble sheet membrane or Protecto wrap. Look it up. Check the diagrams for Schluter materials. Great resource.

Everyone thinks that no water will blow in because it has a roof. Maybe. Maybe the homeowner will want to wash his floor with a hose. What happens to the floor then? Plan for the worst when doing exterior tile. Can you afford to replace it if you don't?

 

Red Guard can be used for exterior waterproofing. Of course, there are certain limitations. Can't be used to bridge control joints, temperature restrictions.... Best to call their Technical services for their blessing.

I've used it for a BBQ area job and no problems.

My favorite exterior waterproofing is a sheet membrane though. You know it's a certain manufactured thickness unlike liquids.