Yes – to install slabs or tiles on top of an EPDM flat roof is certainly a commonly used option. There are a couple of options here depending on the type of decorative finish you require and the design of the slab
1) A slab support, as above, can be utilised underneath the concrete slabs and placed directly on the EPDM rubber membrane. RKD provide paving slab supports which are 15mm high circular plastic discs that support the corners of 4 slabs in a standard checkboard pattern. Water will pass through the gaps in the slabs and safely away to the gutter.
2) If you wish to install a fully bonded ceramic or decorative tile covering on the flat roof you will require to lay a minimum 70mm screed on top of the rubber membrane. You protect the rubber membrane from any sharps in the screed by laying an underlay fleece first.. Tiles or slabs can then be bonded and grouted onto the cement screed as normal.