White thinset is usually selected primarily for the type of stone being installed IE: light coloured stone or translucent marbles. Anything in the white to very light beige range of stone is a prime candidate for white thinset so bleed thru doesn't pose an issue. The same theory applies to grout colours.


Are we talking about the light gray/silver range or some other colour?

I was looking at Harry Dunbars Ditra installation and he put a coat of green coloured primer on the subtrate before laying the ditra .
Should I use this?

he used a primer because the concrete was porous. This sucks the moisture out of the thinset too quickly, resulting in decreased thinset strength and a weaker bond. Most people don't bother with this step, but its a good idea.

What ditra product to use ditra or ditra xl

You only need XL if your trying to match up to a hardwood installation over a regular wood subfloor.

BTW, if you thought regular Ditra was too expensive, wait till you get a price for XL, not to mention it will eat up almost twice as much thinset.

That primer Harry used was probably Kiesel Okatmos UG 30. Great stuff but I doubt you will find it where you are.

Look at amestile.com they are a burnaby wholesaler of tile and setting materials. A good source for ditra and everything you need in BC and they have outstanding customer service.

Ya I phoned there and she wouldnt give a wholesale price as I dont have a business #.
Retail price was $900.00 for a 323' roll

As I am laying the slate diagonally ,should the ditra membrane be laid at the same angle!
What is the best grout line width for 16" slate.

Thanx Huff.

There is no need to go diagonal on the ditra. Grout lines are somewhat a matter of style. If you have slate that is very good quality and consistent thickness then you could go with about 3/16 grout lines. If the tiles vary in size, squareness, and thickness quite a bit (which is usually the case with slate) then you want to be at 1/4 inch or bigger. To me that allows for hiding inconsistently wide grout lines better and bridging height differences with sloped grout.

With slate it's fairly easy to go along after setting the tile and widen any grout lines that are too skinny with a hand held grinder and diamond wheel.