|DITRA over the first layer of thin set|
Another non-toxic thin set to try is C-Cure 911 which does not have synthetic additives.
These non-toxic thin sets are more prone to cracking than ones with additives.
Over the first layer of thin set 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.
|My completed tiled bathroom!|
If that one is not tolerable, Hydroment is recommended for people with sensitivities. However, it has a small amount of latex additives and contains mildewcide. You can make your own with Portland Cement (no additives) mixed with sand, lime and water for a totally chemical-free grout. Here are the ratios.
Sanded grout contains silica (the same substance as glass) which is harmful to breathe in when in dust form. Use a N95 mask (or better) when mixing it until it is fully mixed. This is completely safe when it is no longer in dust form.
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.