How it is installed
The membrane comes in wide rolls, reinforced with a scrim that gives it tear resistance. It is held to the roof in two common ways.
- Mechanical fastening. Screws and plates hold it to the deck along the seams. The next sheet covers the fasteners.
- Fully adhered. The membrane is glued over its whole surface to a cover board.
In both cases the sheets overlap and the seam is melted with hot air. The two sheets then become a single piece.
Strengths on a large roof
- The white surface. It reflects sunlight and helps meet the rules of boroughs that require a reflective material. The solar reflectance index is on the manufacturer's data sheet.
- The weight. The system is light and suits the steel decks of warehouses and industrial buildings.
- Speed. Wide rolls quickly cover large open surfaces.
- No flame. With mechanical fastening, the job gives off few odours, an advantage on an occupied building. With full adhesion, the adhesive can smell strong.
Its limits
- A single layer. A dropped screw, a fallen tool or a panel dragged across the roof can puncture the membrane.
- The weld depends on the operator. Temperature, speed and clean surfaces must be right. A poorly melted seam looks fine and opens later. Welds are checked with a probe throughout the installation.
- Details. Around equipment, every corner and every pipe needs a piece welded by hand. The more cluttered the roof, the more the speed advantage melts away.
- Kitchen exhaust. Grease from restaurant hoods can degrade the membrane. Ask the manufacturer what protection to plan.
Which buildings it suits
TPO suits large open roofs well, such as warehouses, light industrial buildings and big-box commercial buildings. Without added protection, it suits roofs with heavy foot traffic less well.
Depending on the manufacturer and the quality of installation, a TPO membrane lasts in the range of 20 to 30 years.
What to ask us
- Our experience with this system, on roofs of a comparable size.
- The membrane thickness, written in our quote.
- How we will check the welds.
- The protection planned in traffic areas and around mechanical equipment.
Frequently asked questions
Does TPO hold up to Quebec winters?
Yes, a TPO membrane is designed to stay flexible in the cold once installed. Installing it in cold weather is more demanding, and the welding then needs precise settings. Ask us how we work off season.
How do you repair a punctured TPO membrane?
A punctured TPO membrane is repaired by cleaning the surface and welding a patch of the same membrane over the hole. An older membrane needs more careful preparation.
Does a TPO roof meet the white roof requirement?
A white membrane reflects sunlight well, but the value on the manufacturer's data sheet is what counts. The required threshold ranges from 56 to 82 depending on the borough. Have compliance confirmed before the order.