Asphalt-shingle roofs last somewhere between 15 and 30 years, depending on the quality of the materials and climatic conditions. Wind can often cause as much damage as water, cold temperatures and sun. Regular maintenance – which includes operations such as cleaning downspout and gutter installations – and proper attic ventilation help extend the useful life of roofs. Other measures are regular inspections to detect problems at early stage before causing costly damage to your property. The gravity of the problems and age of the roof are key factors in determining whether your roof should be repaired or replaced.

IMPORTANT: Before repairing or replacing your roof, we recommend you to seek advice from a professional roofer. In the short and medium term, this precaution may prevent more unfortunate and costly problems.

Types of roofing materials Asphalt shingles – These consist of asphalt or fiberglass shingles saturated with bitumen and coated with mineral granules. Asphalt shingles are available in sheets or strips. Some are self-adhesive. The shingles are laid over felt paper and plywood. It is an ideal material for slope roofs.

Average useful life: 20 years

Wood shingles – Wood shingles are installed overlapping each other over felt paper. The bottom layer must consist of wood boards spaced apart. This type of roofing material calls for regular maintenance.

Average useful life: 20 to 25 years

Gravel and tar – This material consists of gravel and multiple layers of tar-saturated felt paper. It is particularly appropriate for flat or low slope roofs.

Average useful life: 30 years

Membrane – Made of elastomer, this product is sold in rolls. Joints must be weld-sealed.

Average useful life: 20 to 25 years

Sheet metal – Sheet metal has been used for industrial, agricultural and residential roofs for more than 60 years. It requires less maintenance and lasts longer than most other roofing materials. Regular maintenance can extend its average duration.

Average useful life: 40 years

Metallic tiles – Made of high quality material, metallic tiles consist of thin metal sheets. In general, these sheets are assembled with fold seams. This type of roofing material has a longer lifetime.

Average useful life: 50 years

Roof ventilation and isolation

Proper ventilation prevents premature roof ageing as well as formation and accumulation of ice barriers in attics. When the temperature is just below freezing point (between 0 and -10 °C), the inferior layer of snow covering the roof melts. The water thus produced freezes when it comes into contact with a non-heated portion of the roof. This leads to the formation of an ice barrier in the inferior part of slope roofs. The water can migrate under the shingles and infiltrate the roof space, walls and ceilings.

Ventilation techniques for shingle roofing

Consult a professional roofer of your region or visit the Canada Mortgage and Housing Corporation: www.chmc.ca