How to Tile a Flat Roof

Updated July 20, 2017

Flat roofs are mostly seen on buildings, as opposed to houses. The materials used to create such roofs require uniquely inclined tiles to allow water to run freely off the surface during rainy seasons. Most flat roofs use gravel and tar as their base surface. However, these materials tend to crack after being exposed to cold climates or severe weather. Tiles assure a flat roof's durability and permanence. Tiling a flat roof is not difficult with the help of the right materials.

Install the underlayment across the roof’s sheathing. Run the first sheet of underlayment across the roof’s surface. Set the next sheet beside the first one, overlapping the sheets at least 3 inches. Install the rest of the underlayment sheets the same way, overlapping each other. Remove any excess underlayment around corners and vents using your razor knife.

Nail the 2-inch cant strips near the overhanging lower edge of the roof with your hammer. The strip should be twice as thick as the battens. Slant the first batch of tiles to match the courses. Allow at least 1/2-inch gap for every 4 feet distance. This will allow the water to drain across the row when rain hits the roof.

Measure the length of the tile used, starting at the lower edge of the roof. Position the tiles so they have 1-inch overhang at the roof’s eave and another 1/2-inch head lug at the tile’s rear. The head lug is used to connect the tiles to each other. Repeat the same step for both ends of your roof. Snap a line at the eaves of the roof with your chalk box.

Nail the battens onto the underlayment. Lay down the tiles from left to right to follow a vertical pattern. Remove any foreign objects to ensure that the tiles are properly interlocked against each other.


The number of tiles that you will fasten or nail depends on the slope of your roof. You must also anticipate the wind velocity in the roof’s area to determine how many roof tiles you should use.

Things You'll Need

  • Self-adhering underlayment
  • Razor knife
  • Nails
  • Hammer
  • 2-inch cant strips
  • Tiles
  • Measuring tape
  • Chalk box
  • Battens
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About the Author

Based in New Jersey, Michelle Raphael has been writing computer and technology articles since 1997. Her work has appeared in “Mac World” magazine and “PC Connections” magazine. Raphael received the George M. Lilly Literary Award in 2000. She holds a Bachelor of Arts in political science from California State University.