The best time to replace a roof is between March 21 and September 21, because the sun’s heat helps the shingles bond together better. Cold weather, conversely, reduces the effectiveness of the self-adhesive strips under the shingles. A roof can still be reshingled at other times of year, as long as the roofer adjusts the installation method (e.g., adding glue dots under the shingles).
Decking (or sheathing)
Usually made from 1⁄2-inch plywood, the decking closes and reinforces the roof structure and provides a nailbed for the shingles.Under the Quebec Construction Code, certain kinds of particleboard are also authorized.
Roof edge (or eaves edge)
All the boards running along the edge of the roof or eaves. Also known as a fascia.
Attic
The space under the roof. The attic must be ventilated to protect the roofing system against excessive heat in summer and warm moist air generated by the house in winter. Excess humidity can turn into frost if it comes into contact with cold surfaces under the roofing.
Saddle
A structure located behind the higher side of a chimney (or similar projections from the roof) to divert rainwater around it.
Ridge
Horizontal line at the top of the roof.
Valley
The “V-cut” angle along the junction of two slopes of a roof.To ensure the valley is watertight, it is covered by flashing, made of a flexible material or of metal—or, better still, a combination of the two.
Underlay membrane
This coating, made of felt saturated with asphalt or a synthetic fabric, protects the shingles against resin released by the wood decking, and protects the decking itself against bad weather.Ice damming on roofs: zero tolerance!
Eaves membrane
This protective membrane goes under some or all of the asphalt shingles to prevent water infiltration caused by “ice dams” in winter. Read our Tips & Tricks instalmentIce damming on roofs: zero tolerance!
Underlay membrane
This coating, made of felt saturated with asphalt or a synthetic fabric, protects the shingles against resin released by the wood decking, and protects the decking itself against bad weather.This membrane is mandatory to obtain certain warranties.
Drip edge
Moulding that covers the edge of the roof and reduces the risk of water infiltration.While not required by the Code, it is recommended by roofers and manufacturers. It is attached directly to the decking, along the bottom of the roof slope and above the underlay, on the sides of the roof.
Roof vents
These enclosed structures made of metal or plastic feature openings and fins, ensuring that the attic space is properly ventilated. The most effective vents have four open sides and rise above the roof, which allows them to capture the wind from all directions to produce a suction effect. To achieve full ventilation of the attic, there must be an air inlet at the base of the roof, through perforations in the eaves soffit. Most often made of perforated aluminium, this piece closes off the underside of the eaves.
Deflector
This is a piece of polystyrene or cardboard inserted between two rafters to ensure the free flow of air over the insulation near the soffits. There should be at least 2 inches of space under the decking.
Plumbing vent
A pipe that emerges from the roof and admits air into the plumbing system to allow wastewater to flow properly to the sewer or septic-system leaching field.
Flashing (joint covers)
Flashing can be flexible or rigid and is made of galvanized steel, aluminum or plastic. It is a type of resistant moulding that prevents water flowing near roof openings from infiltrating the roof. Flashing is found in valleys and at the bases of chimneys, walls, roof vents and plumbing vents.
Shingles
Made of fibreglass and asphalt, shingles protect the roof from rain and lend a house character.
