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I have a sub that feels that a full 1″ mortar bed is required. Another feels that 3/4″ is all you need.
Both will set the bed on tar paper and will put in diamond lathe, so that seems ok.
What is the proper thickness for a mortar bed? The substrate is 1 1/8″ ply.
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Replies
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The Tile Council of America Handbook states the thickness of the mortar can be 3/4 if the area is smaller than 100 sf and that the mortar thickness should be 1 1/4 for areas larger than 100 sf. This method (F145-99) states the minimum subfloor is 3/4 exterior plywood over joists 16" oc.
If your floor is level and small you can use 3/4 but if there are high spots that would cause the bed to be thinner you could have problems that you wouldn't have if you used 1 1/4.
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I had to replace tile set in mortar on shower walls once and believe you me, it was far from a treat. The 20 or so tile I had to replace, soon turned into 45 once I got done chipping corners of the next one here and there. As for thickness of the mortar bed, I have found most to be 1 inch thick or so. I've only done minor work with mortar beds however.
Pete Draganic
*I don't do mud sets but, the 2 old boys that used to set tile on our houses ran 5/8"-3/4". These guys had learned the trade from guys from Italy. Wet-mudsets was how they laid floors and walls. They had set tile for about 35 years each. Their work was impeccable and their work held up.Joe
*Tom didn't say and no one asked whether the installation was floors, walls, countertops, etc. Each has a different mortar bed minimum thickness requirement. Floors: 2.25" as specified by the AIA. However, lacking AIA specifications, the TCA specs become the standard (as their are no mfg. specs here). TCA recommends a nominal thickness of 1.25" for exterior and interior floors. Over 2", the mortar bed shall be spec'd per archy.Interior walls: Each installation method details a different mortar bed thickness. 3/8--1 3/4" is within the variation found among these different methods. However, the "mud cap" trim tile has a radius of 5/8--3/4". Therefore, the mortar bed thickness should be the same as the tile radius.Countertops: The TCA specs 3/4--1 1/2" over a plywood base. Personally, I would not go thinner than one inch to avoid weakening the mud base. Also, be sure to kerf that plywood full legnth and ever 6--8" to allow wood expansion without cracking the tile or mud base.My wife says I give too much information. You think? I'm not prepared to give the minimums, thereby encouraging a half-ass job.
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I have a sub that feels that a full 1" mortar bed is required. Another feels that 3/4" is all you need.
Both will set the bed on tar paper and will put in diamond lathe, so that seems ok.
What is the proper thickness for a mortar bed? The substrate is 1 1/8" ply.