# Having my screened in porch tiled



## Alex PCI (Nov 15, 2003)

I'm a painting contractor that knows nothing about tile. I am having my screened in porch tiled and I was wondering if I should prime the floor first with an oil base primer? You can see in the pic that it is just a bare sub floor now, this room was originally built to be an addition that would hold a hot tub so it was built very strong. It sits about 4 feet of the ground and I was just worried about a moisture problem later on thats why the primer idea came about.
Thanks for the help


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## JazMan (Feb 16, 2007)

Hi Alex,

Floors should never be painted. Do not prime that subfloor, it would do no good anyway since the tiles are not going directly on to it anyway. 

First of all, how are you going to keep the rain out? The floor looks flat, you need windows. Also, those walls look like wallboard to me, how is that going to work out? 

It would be nice if I knew where your house is located so I would have a general idea what type of weather you're going to experience. 

Have you talked to the tile setter about which of the many methods and specific products are going to be used to install the tiles? Have you made a tile selection? What size are your joists, do you know the grade and species of the wood, what is the unsupported span? The joists look like they are spaced 16" o.c. right? 

Jaz


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## Alex PCI (Nov 15, 2003)

Its a screened in porch, no windows. It was built to handle exterior weather and it only gets wet during a hard rain thats why I chose a porcelain tile. I live in NC, its gets kinda cold in the winter barley ever snows but it does get to the high 90's for a couple months like it is now. The tile setter did my kitchen and I assume is fairly knowledgeable about this, he did explain the method he would use. I put that drain in, its basically just sitting there unmounted for now. I wanted to be able to spray the tile off with a hose if need be to clean it. I think the joists are 16" but im not sure, i need to take a picture of the bottom of the porch, this thing was built way over spec. The walls are not wallboard, they are exterior plywood soon to be covered with wanes coating


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## HJ1 (Sep 28, 2006)

That looks like a pretty big room. What are the rooms dimensions? Is there a center support midway under the joists? I know you say its built way over spec but if theres no support below to cut down that span your floor may not be suitable for tile. What size are the joists?

You said your tile setter explained the method he would use? What is it? Will he be sloping the floor towards the drain 1/4" per foot and if so, how? Will he be waterproofing under the tile? Tile and grout are not waterproof, even when you seal the grout. There has to be a waterproofing membrane underneath the tile and the waterproofing system should incorporate sealing to the drain. It would also be a good idea if the waterproofing system went a few inches up the wall as well. What kind of tile will you be using?

And no, dont paint the subfloor.


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## Alex PCI (Nov 15, 2003)

The room to be tiled is 14'x16' and it has a center support, if this thing cant hold tile I give up. The drain is only there for a once or twice a year spraying off, the rest of the time it will just be swept clean. Im glad I didnt do the tile myself, so backerboard and thinset wont be enough? What type of waterproofing should be used? Im glad I asked you guys before I painted the floor, i was just about to roll it on


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## JazMan (Feb 16, 2007)

Essentially what you would have if you continue as planned is a floor just like any old kitchen floor. You cannot allow it to get wet from a hard rain and you cannot rinse it off...ever. The part you won't see, (everything under the tile), will get wet and will not be able to dry. 

If you do not get windows, you need some kind of waterproofing system AND the floor needs to be sloped to the drain. You would treat this room like a shower floor. Not just sloped, but sloped and waterproofed. 

Jaz


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## Alex PCI (Nov 15, 2003)

What waterproofing system should be used? And does it go under the backer board or under the tile?
Thanks


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## HJ1 (Sep 28, 2006)

Check out this link for waterproofing system.

http://www.schluter.com/2080.aspx


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## Alex PCI (Nov 15, 2003)

with the ditra do you even need backerboard?


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## JazMan (Feb 16, 2007)

In this case you can substitute Ditra for the CBU, and the results will be better performance. To make the floor water-proof, install Kerdi Band on all seams and at floor/wall juntions. 

This is the 'indoor method'. When we specify Ditra on an exterior deck etc. we want plywood, a cement board suitable for exterior use, topped with Ditra and then the tiles. 

If you still want a drain, see the installation detail for a Kerdi Drain installed for this type on floor, as apposed to shower floor installation. Even when waterproofed you should still not hose the area, because the room is not sloped. 

Any bets that 95% of the tile installers won't know what Ditra or Kerdi are?:no:



Jaz


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## Alex PCI (Nov 15, 2003)

to think i almost tackled this project myself........

if tile installers dont know about this product how are they waterproofing there installs??


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## JazMan (Feb 16, 2007)

Some do and some don't. For a job like yours, many might not bring up the idea of waterproofing for fear of loosing the job. Even if done wrong, it would look great for a few years or so? Those that want to do top notch work or are accustomed to doing high-end commercial work where waterproofing is spec'd, know how it should be done. There are many products and methods to do the same thing. Find what is common and available in your area.

On the other hand, you could do the job yourself. It might even turn out better? :thumbup:

Jaz


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## Alex PCI (Nov 15, 2003)

Thanks for all the great info. I just saw a roll of that Ditra for 69.99 per 55sqft. at home depot, does that price sound right or can it be bought cheaper


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## JazMan (Feb 16, 2007)

That is what HD sells it for all across the country, although not all store carry it. That is a very good retail price. I buy it in full normal sized rolls containing 323 sq. ft. I would say it's worth about 1.75 sq. ft. or so per ft.

Jaz


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## Mr.Werks (Aug 23, 2007)

Hi Alex:

Not sure if you have completed your tile install yet.
I have installed slate on exterior sidewalk and wood decks. I use flextile membrane system. You can read about the product on Flextile website It is a two part system that provides waterproofing and helps in the freezing and thaw stages of the year. The material cost is reasonable and with your painting experience you can install this product yourself saving on labour. Follow the instruction exactly and you will enjoy your new porch for years.
And remember the less water the better, just mop like you would the kitchen floor no need to spray it down. One idea to consider would be to bring the membrane up the wall 4 inches, and install a border tile, would look nice and finished.


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## Alex PCI (Nov 15, 2003)

still havent got to it yet, been to busy....now I have to fix my bath floor because of a shower leak


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## JazMan (Feb 16, 2007)

Sorry to hear that. Do you know the cause of the leak? Sometimes takes some detective work. Tell us what happened if you're stumped.

Jaz


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## Alex PCI (Nov 15, 2003)

heres a link to the thread about my bath floor. Thanks again for all the help
http://www.contractortalk.com/showthread.php?t=25974


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## MattCoops (Apr 7, 2006)

I suggest ditra with kerdi band at seems and corners as waterproofing underlayment.
After waterproofing, you'll need to float a mud bed with a 1/4" slope towards drain.
This may not be a task a novice tile setter can tackle.

Or, you could remove the drain and install windows.
Then install a backerboard system over thinset, and then tile away.


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## HJ1 (Sep 28, 2006)

A mud bed over ditra, now thats a new one on me. Nothing over the ditra except thinset and tile. Any slope would go under the waterproofing not over it.


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