When I built the house I wanted all my bathrooms, hallways and the kitchen floor to be tiled which was close to about 1500 square feet. The main floor is actually the second floor of the house so it's built from 3/4 inch tongue and groove plywood over 2 by 12 yellow pine resting on some steel beams because I have a 20 foot span over the Crawlspace where the Top Secret Tornado Bunker is to be located then a 27 foot span for the bottom level which is a workshop, 3 car garage, storage room and bathroom. I was worried about tiling the kitchen mostly because it was such a high traffic area and a big span over nothing. The room is 14 by 27 with a large pantry and its sitting above the 3 car garage. You can't tile directly to the wood because the wood expands and contracts differently than mortar will so generally people use backer board which is like a 3 by 5 foot sheet of 1/2 thick masonry product and works very well but it's close to $10 a piece and I was gonna most likely need 170 sheets of the stuff.

I also worried what to do about the seams. I am sure they must want them taped and mudded before you tile them but I'm no expert and haven't researched it but I'd cover them with screen and mortar them just because.

I was worried about the seams expanding between sheets and maybe cracking the tiles plus its pretty dusty if you use a skill saw to cut it. You can use a razor blade which is fine if you just have to do a bunch of rectangular areas but it's a pain on a big job and another reason was as far as building funds were at the time, we were running on fumes so to save $1000 would be a big deal.

I googled a while and read about mudpans and then asked a few older builders I know, if they'd ever done any and was told that's how they used to do it so I thought a bit more about the fiberglass they put in concrete so you don't have to put down screen and my mortar mixer and the bounty of sand you can find in Florida and I came up with this method which hasn't shown any cracks or problems in the last 18 months or so that the floors have been down.

Step 1: Basic Method

Basically this is like pouring a concrete slab just on a smaller scale. I poured these mudpans about 5/8 of an inch thick and I wouldn't think anything less than 1/2 would be wise.

I wanted a bit of room between the wall and the floor for expansion and contraction so I decided to use treated lumber for what is essentially the form for the slab. I wanted to leave these in place after the mudpans were done mostly because I figured if I went back and tried to pry them loose I'd crack the mudpan plus I stapled roofing felt down on the floor again for expansion / contraction and the wood worked very well to secure the borders. I left about a 3/8 inch gap between the wood strips and wall and then filled it with expanding foam and cut it flush before pouring the cement. I overlapped the felt the same as you do when doing a roof. I used the heavier felt just out of habit but looking back this would have been a good time to use the lighter felt because you want it to lay down fairly flat and want to be sure the weight of 5/8 of an inch can force down any bumps which would cause a thin spot.

Okay, I see that I already had a "login" thingy from about a year ago. The above was a "login from Facebook", but I don't like that it used my name like that. Please pretend you never looked at it, k? :)
Okay... I figured out how to "login" on that redundant "account" that showed off my name and delete the other message. So please disregard that message saying you should disregard my message. Nothing to see here... Is that a black helicopter I hear??
HI I've used a product called mapailath(available at rona but not home depot),a blue plastic screen,that you staple(5/8") down,use the same thinset( or self-leveling concrete to fill it in. You end up with an 3/8" (approx) subfloor. The kerdi stuff is good too,but you have to put down a scratchcoat first, lay-out and smooth the kerdi,then run your thin-set over it etc.. Another alternative is,if you know that your wood substrate, is for sure 1 1/4" thick and well screwed down, you can use a modified thinset directly onto the wood,(yes I do mean just a scratchcoat)1/16" thick. do not leave any bare spots, and you must back-butter every piece reguardless of tile size.
Hmm. Effective, but... I'm just a bit concerned about maintainability. Backer board can be cut reasonably cleanly, if you remodel and need to run something through the tiled are (radiator pipe, for example). I'm just a bit concerned that this fiberglass-reinforced concrete would be more durable than you might want it to be.
It's only 5/8 of an inch thick or so on average and the sand mix is a bit higher so it is softer and with no gravel you can saw or drill through it.
Would love to see you add this to my new group.<br/>Hope to see you there.<br/><a rel="nofollow" href="https://www.instructables.com/group/fixit/">Home Repair, Refurbishment, and New Projects</a><br/>
Nice job. My only question is how "crushable" the spray foam. I know that we sometimes use it inside of car panels to reinforce them. Although there is a lot more in quantity, the direction of compression is more important. Also, I wouldn't worry about the comparative weight of the felt. That much mud will either push down any wrinkles or flow over it anyways. Innovative. Well done.
Now that is what I am talking about! My kinda thinkin! I will remember this one for sure. Good idea and good job, the floor looks great. It gives me an idea for another project. I like your idea of the treated lumber and the foam, smart move there. I am just really impressed by this one.
Thanks! I need to make one on doing my hardwood floors. I also filled the gap with spray foam and cut it flush to the floor before I started sanding and finishing it. Having the expansion gap around the perimeter of the floor filled really made a difference cleaning up the fine saw dust prior to using the polyuerethane.
Okay, wait... I'm totally confused! What did you use under the floors instead of backboard? Mud pans? Screens? Fiberglass? Insulation? Please enlighten me -- we're about 12 mos away from building our own house too, so I'm all ears when it comes to money saving tips!
Mud Pan's are what I used primarily except for a bit of Backer board I used in the Master Bath since I heated that floor, and that was primarily to keep things simple. I don't understand what you're confused about?
This looks really good. It's got nice pictures, nice descriptions. It must have taken a lot of BS&T to get this just right.
Thanks for the tips!

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Bio: http://senseless.livejournal.com/ I've been attempting to build a house mostly by myself for the last five years... I finally more or less ... More »
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