I just had the tiling done in my tiny house bathroom and in the process learnt a lot about chemical-free grouts and thinset mortars.
|DITRA over the first layer of thinset|
I used Custom building Products’ Thin Set Mortar which is zero-VOC. It had a bit of a smell when wet but seemed fine once dry. You want a water-based thinset that is not mixed with latex or acrylic additives. Avoid the toxic epoxy thinsets. Avoid mastics as well.
Another non-toxic thinset to try is C-Cure 911 which does not have synthetic additives.
These non-toxic thinsets are more prone to cracking than ones with additives.
Over the first layer of thinset I used Schluter DITRA, an uncoupling membrane that will help prevent cracking when my tiny house moves.
If you just need a waterproofing membrane use Schluter Kerdi. These are both made out of polyethylene and do not have a smell. They will act as a vapour barrier if your subflooring is toxic.
|My completed tiled bathroom!|
I used this Grout, the same brand as the thinset, which is also zero-VOC. It comes in sanded and unsanded and in different colours. It barely had a smell.
If that one is not tolerable, try Hydroment which is free of latex additives, or make your own with Portland Cement (no additives) mixed with sand, lime and water for a chemical-free grout. Here are the ratios.
I used concrete tiles from Morocco. For more on choosing non-toxic tiles see my post on bathrooms.
I sealed the concrete tiles and grout with AFM Safecoat Penetrating Water Stop. Grout is porous and should be sealed regularly to prevent mould. If just sealing grout (and not tiles) use AFM Safecoat Grout Sealer.