I am soliciting bids for my home to be tiled with 12”x60” rectified tile on an 11 year old slab. I requested that a decoupling membrane be used because we have a clay gumbo soil (texas coastal region) and i‘m comfortable paying the extra cost for potential extra insurance on tiles this large. so far two contractors I’ve spoken to are saying they won’t use it with one making it seem outright silly to use.
Where i get uncomfortable is the first is leaning on their lifetime warranty and claiming that because they use a modified thinset, there will be some give there and if i have cracking, they’ll fix it under warranty. the problem is that their warranty verbiage only covers installation defects. obviously my hypothetical moving slab would not be an installation defect and i question how much a modified thinset will actually absorb any movement. The second hasn’t gotten back to me yet when pressed further. Obviously if there is major movement, the tile is going to crack anyway…i get that.
the slab is in good condition. there is a hairline crack in the middle of the house, but it is very thin and most likely from the initial cure, we think. no sticking doors or windows or cracked drywall to indicate movement on the inside, however there is some hairline cracking through exterior brick (straight line, no stairstep) in one area that we have been told by a mason is from the soil expansion/contraction and most likely not a concern, but to keep an eye on it. similarly there are some areas where there is a horizontal crack between the bottom row of brick and the foundation, but no evidence in those areas on the inside of any issues yet and we were told to seal and keep an eye on it.
i feel that the extra cost of the decoupling mat is worth it, but this is apparently not often done in the greater Houston area. another thing I’ve run into, is they won’t do mock ups with grout colors. i get that the tiles are large, but i assumed they could cut some slices and show me a few color options between two slices of tile; is this not typical for floor tile? I’ve not found the grout sample chips to be particularly true to the finished grout product and this is a big job, so i want to make sure I’m making the right selection. ultimately i will just buy the grout and make the samples myself, but i thought that would be standard practice.
for flooring in the Houston area, given the soil type and frequent wet/dry cycles…would you forego a decoupling membrane? or would you consider it a non-negotiable. Would you consider the attempted reassurance of the modified thinset to be outright dishonest in a way that would warrant seeking other outfits, or is there some truth to this claim?
Thanks for any help you can provide!