How to Tile Over a 2nd Floor Deck

Cut the first course of uncoupling membrane with a razor knife to fit along one end of the deck. Trace around the piece onto the deck. Remove the membrane and cover the traced area with thin set, using your notched trowel.

Press the membrane into the mortar, getting it firmly set all over the surface.

Repeat the process, cutting and laying additional strips to cover the whole floor. The edges should be butted tightly together. Let the mortar set overnight.

Divide the membrane surface into four areas by putting down two intersecting lines with your chalk snap line -- running between the two center points of the long sides and the center points of the narrow sides.

Use your notched trowel to spread thin-set into one corner of the intersection at the center of the floor, covering four square feet or so.

Press a tile in place in the mortar at the center, bordered by the two lines. Set more tiles next to it, putting spacers between them as you go. Build your way out from the center point toward the edges, spreading more mortar as needed.

If needed, cut tiles for the edges on a tile cutter and set them in place.

Allow the tiles to set for 12 hours. Remove the spacers.

Spread grout onto the surface with your grout float, pressing it into the gaps between the tiles and scraping it off the surface. Use a dampened sponge to take up the residual grout from the tile faces, leaving it in the spaces. Let it set for one to two days.