I am planning to use Schluter Ditra membrane on a tiling project in my kitchen. I ripped up the existing vinyl stick-on tile, and I found black mastic underneath which I think contains asbestos. This is sitting on a 5/8" plywood layer, which is on top of the original tongue-and-groove subfloor.
I don't want to scrape up the mastic, because it's bonded tightly to the plywood and it seems like a lot of work, especially with the asbestos risk. Can I screw a 1/4" or 3/8" plywood sheet on top of the black mastic, and then apply the Ditra and tile on top of that? Could I use this "waferboard", which I'm not sure if it's the same as OSB? https://www.menards.com/main/building-materials/panel-products/osb-sheathing/1-4-x-4-x-8-waferboard/1242427/p-1444422444696-c-13330.htm?tid=-3933426270036270705&ipos=5