How to Install Tile on EPDM

EPDM is a roofing membrane used to provide a waterproof layer on flat rooftops. Most of these layered rooftops remain empty, but there is a way to utilize this space by placing tiles onto the EDPM, creating a rooftop deck. There is a problem with traditional tiling methods when dealing with EPDM, though. The material is incompatible with the alkaline nature of Portland cement, making most tile adhesives unusable. Installing nonadhesive interlocking tile on EPDM deals with the problem of adhesives. The nonadhesive tiles allow you to lay a complete tiled surface without damaging the membrane. Once placed, you have a strong durable surface created from the large variety of interlocking tiles available.

Installing tile over EDPM can turn a flat roof into a deck.
  1. Clean the surface of the EPDM, sweeping it thoroughly to remove any dirt or debris present

  2. Measure points along the straightest wall available the length of a tile plus 1/4 inch from the wall, marking the points with a piece of chalk. Place a chalk line along the measured points and snap a line onto the EPDM. Snap the line by raising the chalk line slightly above the surface of the EPDM and then releasing it to hit the material, creating a straight line at the measured distance from the wall.

  3. Place the first tile onto the EPDM, starting 1/4 inch from the leftmost corner of the measured wall. Place the flat edges of the tile facing the walls, with the two tabbed edges facing towards the interior of the room. Attach the second tile to the first, following the wall and using the chalked line as a guide for the tabbed edge to create a straight row. Hook the tiles together using the tabs, with the flat edges of the second tile hooked to the tabbed edge of the first and lined with the wall. The 1/4-inch gap provides space for the tiled surface to expand with temperature changes. Continue with tile placement, working from left to right, until the row is completed. Tap the tiles in place at the joints using the rubber-headed mallet.

  4. Cut the edge piece of tile to fit the space against the far wall, removing the tabs and creating a flat edge by marking a cutting line onto the tile that ends the tile 1/4 inch from the wall. Cut the line by placing the straight edge of the carpenter's square onto the cutting line and cutting the tile using a utility knife.

  5. Place the remaining rows of tiles, using the same process as the first row's placement, until you have covered the entire surface. The weight of the interlocking tiles will prevent the surface from moving atop the EPDM.

  6. Finish the tile placement by caulking the perimeter of the tile surface to keep water from flowing beneath the tiles.