This is one of the oldest roofing systems and is capable of lasting 40 to 60 years. These roofs have had major advancements however with some coming with integrated solar or snow removal systems. 

Common materials used for metal roofing include Aluminium, Copper and Corrugated galvanized steel. 

Metal roofs can be very attractive design-wise and have strong fire resistance capabilities. The biggest drawback to metal roofing is the susceptibility to corrosion.

These are installed by alternating layers of tar topped up with stone or gravel hence their name “tar and gravel” roofs. These roofs have a relatively low durability rate of 20 years going up. This can however be increased by topping up the number of layers but it comes at a cost. 

Built-up roofs are generally inexpensive and low maintenance. They can sustain foot traffic and are UV resistant. Other than the lack of durability, these roofs also prove difficult to identify a leak.

Shingle roofs are common in homes but they can also be used for steep-slope commercial roofing. There are many variations but the two most common ones are Asphalt Shingles and Architectural Shingles. Shingle roofs are affordable, easy to install and durable (Architectural ). They are however susceptible to mildew or moss and the Asphalt shingles lack durability.

These are applied to an existing roof by spraying a material called Spray Polyurethane Foam (SPF). The material begins as a liquid, changes to foam then hardens into a layer. Spray-On roofs add insulation, waterproof and are durable for up to 50 years. The installation however must be done in favourable weather conditions (no snow, no ice and no water).

EPDM is a roll-based, synthetic rubber roofing membrane that is durable and offers strong resistance to sunlight and pollution. The material is also capable of resisting solvents such as alcohol and acids. 

This material however lacks in design and punctures easily.