If starting from joists, what subfloor would you use these days? 18mm Ply first and then a 6mm backer board layer? (correct thicknesses?). Plan is to tile floor with porcelain tile 20x20cm, electric heating mat under. Thanks.
18mm chipboard glued and screwed, 6mm wedi glue and screwed with washers, then vario pro/ ditra heat type matting and tile. Will be a nice height for threshold to meet carpet