I need to know what my best underlayment option is for ceramic tile based on MY PERSONAL CRITERIA. Please help. I have tried to outline all the information below. If some going back and forth is required I will be glad to clarify or answer any questions you might have.
A special note:
The Tile Council of America doesn't have my personal criteria in mind. The Tile Council of America has emphasis on quality beyond economic sanity. I have to run my business as a business so I am seeking your help instead of just doing what the Tile Council of America tells me.
Here is my opinion. And just for the record, I USED to lay tile and did so for just a couple years. Most of my tiling experience was new construction but did do a few remodels as well.
OK Here goes....
Situation: It doesn't sound to me like the floor/area to be tiled is too expansive and sounds like it should be fairly sturdy "Floor spans:
12-15 ft; Joist spacing: 16 inches on center; Joist size: 2x10 (some
2x8); Basement present: Yes, on all; current floor: painted and unpainted floor boards 1x6 and 1x4 (3/4" thick)". Though this is hard to say with any certainty just by reading a few specs.
Here is what I might consider:
Plan A: I have used wonderboard before to tile over subfloor and have used it on stairways that were somewhat rickety. I layed the wonderboard onto a spread of latex added thinset and then screwed it down. Used thinset with latex to set 12x12 tiles and in 4 years of frequent traffic, no cracks at all. I think this would be a good option because, though more expensive materials, your labor costs would be lower because I think it would take less time. (though this may not be the case depending on your experience and if you are working alone. A person can spread mortar pretty fast and with a helper, could make quick work of this type of installation.)
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Plan B: Though 'mudding' does produce a pretty strong/hard surface, I'm not so sure you could get away with not using metal in it for stregnth. Also, I think this would take alot longer, therefore increasing costs of labor by having to prep, mix, haul, spread, screed, etc. This also requires a good bit of skill to do preoperly. I'm not sure if using fiber cement is enough to not use metal, like you said.
Plan C: I don;t know the 'chemical/or mix' properties of wonderboard but I do know that it does have a fiberglass mesh on both sides for stregnth. You pay more for convenience. Buy it, deliver it, install it. no mess, no mix, etc. As for the 1/8 difference in floor height. There are 2 thicknesses of wonderboard, 1/2 and 1/4 and you might be able lay wonderboard on a thicker spread of mortar where the floor is higher using a deeper trowel to spread.
Plan D: Be careful using OSB. OSB isn't made for wet applications and may separate with the wet thinset and therefore may not provide a good secure bond. If you suspect any moisture problems, I would not consider this at all.
Plan E: Just read the link.........
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Again, It is hard to know exactly what your up against but these are my opinions based on what I got from your descriptions.
You can also use an addative to the grout and that can help prevent cracks as well. Your local tile distributor/shop should have different additives you can purchase.
the hard way to do it. much more labor intensive to get flat and get right.
another hard way to do it
wood is not to be used for laying tile unless you're going to use exterior, and even in that case, you won't get a good bond using thinset. the wood sucks the water out of the thinset too quickly and you get a crappy hold.
Thanks you VERY MUCH for your input. I was worried that my request might have been a little too "heavy" to elicit any worthwhile help. I am very thankful for your time.
No one seems to object to the idea of me making my own "high performance mud bed" (except it might be take extra time and prove difficult to produce a flat surface). Everyone seemed to champion the official Wonderboard product.
I did a little research and ended up purchasing 5.40 ounce/M2 6X6 mesh/inch white coated alkali resistant fiberglass mesh fabric. Based on my calculations I will be able to lay a 3/4 inch mudbed of 1:1:4 (portland/lime/sand) fiber reinforced mortar with fiberglass mesh embedded near the top and bottom for a cost of $1835 plus labor. This is $1332 less than the cost of Wonderboard. I am gambling the extra work will be less than $1332 in labor costs.
I now have two options:
1.. Attempt to manufacture 334 sheets of Wonderboard in my basement and then install as regular Wonderboard 2.. Embed the fiberglass mesh within a monolithic mud bed I would like to hire someone for $10/hour to make the Wonderboard in my basement. If they could average a sheet every five minutes the total labor cost would be about $280. The total savings would be $1052. This would allow me to wet cure the 11.57 yards of underlayment in my basement for a full 30 days to ensure full strength was achieved. Any shrinkage could occur before I installed the boards. This method would allow me to ensure their flatness. Before making the 334 sheets I will make a test board or two and allow it to cure for a week. This will allow me to compare it to the official Wonderboard to ensure it isn't obviously inferior. If the board is inferior (or seems labor intensive) I am only out the cost of the one or two boards ( > Tile Council of America has emphasis on quality beyond economic sanity. I
I'd be interested in hearing how it turns out, if the homemade sheets work ok. Pictures would even be cool also(if you're feeling that much more ambitious). I'm just curious to see how they are made and how it works out.
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