How to fit Porcelain flags outdoor

The 'hardcore' should really be MOT Type 1 granular material as it creates a more stable surface for the mortar than hardcore, so long as it's properly tamped ("whacked'). I allow for 50mm of Type 1 in 2 lifts, with each lift separately tamped to a combined total thickness of 30mm+. Then add 50mm of mortar, prepared fairly wet. Then a bond bridge primer is applied (usually to the back of the tile) to get a good bond between tile and bed. It's tricky work but done carefully it should go well. Key is that the finished surface drains in the right way and doesn't pool anywhere - I go for a 2˚ slope. Good luck!