The use of fiberglass for the realization of flat roofs offers an undeniable advantage, it is the only sealant with high wear resistance. A fiberglass membrane does not require wood bridging or any maintenance for at least 25 years. Given the growing interest of Fiber glass roofing for the construction of roof terraces, this is an attractive approach but which is still experimental.
The use of fiberglass for the realization of flat roofs offers an undeniable advantage; it is the only sealant with high wear resistance. A fiberglass membrane does not require wood bridging or any maintenance for at least 25 years. Given the growing interest of Fiber glass roofing for the construction of roof terraces, this is an attractive approach but which is still experimental.
Preparation of the support
A fiberglass membrane is a relatively hard and brittle material that does not support the movement of joints and sharp edges. It is therefore necessary to ensure that the structure of the roof of the building is strong and stable, since slight sag could cause cracks. We must remove the old asphalt and gravel membrane from the roof to start from the wooden planks forming a firm support. We screw a 5/8 inch (15 mm) plywood of Douglas fir (BC Fir) on the boards as well as on all the vertical walls around the roof. All mechanical outlets, such as attic aerators, plumbing vents or skylights, must also be surrounded by the same screw plywood. Finally, it is necessary to sand all the joints of the panels placed end to end and grind all the sides of the plywoods to round the angles which will receive the fiberglass.
The installation of fiberglass
The installation of fiberglass is done in several stages. We first extend the fiberglass on the roof to remove some of its resilience. It tends to return to its roll form. We start the work with vertical surfaces. We put a first layer of resin with a roller directly on the plywood. The fiberglass is then placed in the resin, crushing it using a very firm roller to make it penetrate the resin. The work must be done in small areas, because the resin hardens quickly. A second layer of resin is then rolled over the fiberglass. These steps are then reproduced for the horizontal roof surface.
Finishing
From the second layer of resin, the roof is waterproof and resistant. The fiberglass then receives a finishing coat with a roller (gel coat ) which gives it its color, texture and pigments. In general, it is recommended to leave a sanded finish if the roof is used as a roof terrace, otherwise the surface becomes very slippery when wet. It is possible to make an entire roof in one day, but for the completion of the top coat, avoid very hot and sunny days because the fiberglass surface becomes softer. Sometimes you have to wait several days before installing the finish on the roof.
Is it a good choice?
The cost of a residential flat fiberglass roof is approximately $ 12.50 per square foot (before taxes and including the vertical surfaces to be covered). A fiberglass roof will not necessarily be more durable than a PVC, TPO, EPDM or elastomeric bitumen membrane, which cost around 25% less. However, with the other membranes, it is necessary to add the cost of a wooden terrace, which will often be more expensive overall. Fiberglass will also be very easy to repair in the event of an accident and very inexpensive to redo in 30 or 40 years, since the base will not have to be redone. In this sense, it is a potentially very durable product but which still has to prove itself under different conditions.
