his paper draws a comparison between the green roofs and the conventional roofs.

The conventional roof has many types. Types of the conventional roof include but are not limited to single-ply roofs, built-up roofs, metal roofs, and asphalt shingle roofs. Single-ply roofs are sheet-like membranes manufactured in the factory. Thermoplastic membranes and thermoset membranes are the two types of single-ply membranes. Built-up roofs contain several layers of reinforced membranes and modified bitumen roofs. Built-up roofs are the most common as well as the oldest type of conventional roofs. They are also called gravel or tar roofs. There are three components in the built-up roofs, which include a layer of waterproofing, a reinforcement layer, topped with a surfacing layer. It is installed with the help of asphalt or coal tar. Structural metal panel roofs are used for roofs with low slopes as they have the characteristic quality of the water barrier. They can also be used for roof assemblies with steep roofs. The structural metal panel roofs are constructed in such a way that water cannot pass through the joints. These roofs are installed in a broad range of substrates. Asphalt shingle roofs are amongst the most commonly used roofs where the slope is steep. There are two types of asphalt shingle roofs. organic roofs and fiberglass roofs. “Organic consists of paper saturated with asphalt to make it waterproof with a top coat of adhesive with embedded ceramic granule” (gogreenconstructionnow.com, n.d.). Owing to their greater weight, organic shingle roofs offer better blow-off resistance as compared to fiberglass roofs. Roof shingles may contain single or multiple layers, but all types contain an adhesive strip which is sun-activated and serves as a sealant for the rows.

There are three main types of green roofs. extensive green roofs, semi-intensive green roofs, and intensive green roofs. Extensive green roofs are used in ecological landscapes. The type of vegetation used in the extensive green roofs ranges from moss and herbs to grasses. The depth of substrate in the extensive green roofs is between 60 mm and 200 mm, and their weight is in the range of 60 kg/m2 to 150 kg/m2 (Livingroofs.org, 2012).