Unlike peaked roofs, which rely on higher-grade slopes to shed water quickly, low-slope or flat roofs tend to be exposed to water for longer periods of time. Therefore, it is essential to use a roofing system that provides an uninterrupted, impermeable seal. To meet this requirement, flat roof construction in Vancouver utilizes a number of different types of flat roof membranes, to ensure commercial building interiors stay dry. These include Built-Up roof membranes, Modified Bitumen roof membranes, and Single-Ply roof membranes such as PVC, TPS and EPDM
Built-Up Roof (BUR) membrane
BUR roofs, otherwise known as tar and gravel roofs, have been ubiquitous in Vancouver flat roof construction for years. They are made using alternating layers of fabric and coal tar. They have a good track record, however the materials are hazardous to people and the environment so there’s been a shift away from BUR roofs.
Modified Bitumen (ModBit) membrane
Modified Bitumen roof membrane is similar to BUR membrane in that it uses layers of material, like SBS (styrene-butadiene-styrene) to provide protection. It is generally easier to apply than BUR roofing membrane and is significantly lighter.
Single-ply (aka 1-ply)
As the name suggests, this flat roof membrane has only one layer so it is crucial that it is installed correctly. Afterwards, a regular schedule of inspections and maintenance will help this type last 30 years or more. These membranes come in varying thicknesses. A thicker layer will be more durable but more expensive as well.
Single-ply flat roof membranes come in 2 types: Thermoplastic, such as PVC or TPO, and Thermoset, with EPDM (ethylene propylene diene monomer), or rubber roof, being the most common.