A flat roof is horizontal or nearly horizontal. Materials that cover flat roofs typically allow the water to run off freely from a very slight inclination.

Tar and gravel based surfaces have traditionally been used to prevent moisture penetration however these surfaces tend to fail in cold climates.

Modern flat roofs now use a continuous membrane covering which can better resist standing pools of water. Lifetime warranty is offered on a residential installation, and up to 25 years on a commercial install. Very energy efficient, the PVC membrane is white and has very good heat reflection qualities.