Common for Business and Industrial Properties.

Flat and semi-flat roofs – often seen on businesses and industrial properties – are on many 1960’s era homes in California.


  • Very affordable but limited to flat or semi-flat roofs
  • Lasts up to 20 years
  • Generally seen more predominantly in industrial and commercial applications
  • Can be finished with layer of decorative stone


Not very attractive

Flat surface can retain water – therefore, not recommended in very humid climates


Affordable – but limited to specific type of roof

Hot Mop:

Mostly seen in commercial applications, hot mopped asphalt roofing is sometimes applied to flat or semi-flat residential roofs that have good access and proper drainage. Roofing materials hold up fairly well when properly applied. The technique results in a roof that’s not very pretty, although in residential use it is often covered with a layer of decorative stone to improve the appearance. The technique requires a large kettle of asphalt with is mopped onto the surface. The finished layer of a hot mop application can be either gravel stone that comes in different sizes and color or cap sheet (similar to shingle)

Torch Down:

Also known as modified bitumen, is widely used for roofing on flat roofs. Its name is derived from the method of torching the bitumen sheets onto a fiberglass base sheet in the roofing overlap areas during torch down roofing installation. The material used in the roofing torch down process is also sometimes known as rubberized asphalt. Melting of the bitumen by torching creates highly resistant and durable roofing. Because of this, torch-down roofs are long-lasting, with an average life span of up to 20 years.

Torch down roofing is applied with a torch rather than a hot mop, and this system eliminates the unpleasant odor of hot mop procedures. It also allows the torch down roof to be repaired more efficiently due to the materials used. In warmer climates where there is minimal rainfall and less chance of freezing, many flat roofs are simply built of masonry or concrete which is good at keeping the dwelling cooler. These roofs are not suitable in very wet and cold/freezing climates because the concrete does not hold up well in those conditions.

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