Choosing the Right Roofing Material for Canada's Climate

Canada is nothing if not a diverse country. A roof that works well in coastal British Columbia, where there is an abundance of rain and temperatures are seldom extreme, are required to meet very different challenges than one in the Prairies, where winters are very cold with heavy snowfall.

One of the more frequent issues that homeowners have is selecting a roofing material without taking these differences into consideration.

Why Climate Should Drive the Material Decision

Each roofing material has its pros and cons associated with it based on its ability to withstand temperature fluctuations, moisture and load. A material that works well in a mild and dry climate may not work well in an area that experiences heavy snows or freeze-thaw conditions.

The purpose is not to select the "best" material but to match the properties of a material to the conditions to which it will be exposed from year to year.

The Climate Factors That Matter Most

Snow Load

Roof slope, structural capacity and material all factor into snow shedding or holding. Efficient snow shedding and roof design to accommodate snow accumulation are both important in snow-heavy areas with high snowfall totals.

Snow Load

Repeated freezing and thawing occurs in many regions of Canada throughout the winter season. This cycle is more demanding on roofing materials than a cycle of a climate with one long and consistent cold season because materials are subjected to the cycles of expansion and contraction, rather than settling into a stable temperature.

Freeze-Thaw Cycles

Sustained precipitation and increased humidity is an issue in coastal regions, especially in British Columbia and Atlantic Canada. Materials and installation information for these areas must deal with a steady flow of moisture instead of sporadic storms.

Heavy Rain and Humidity

Strong sustained winds can occur in open prairie areas as well as coastal areas, and these conditions can influence how to secure materials and the wind resistance of a roofing system.

Comparing Common Roofing Materials

Asphalt Shingles

Despite being a moderately priced roofing material and being widely available, asphalt shingles are still used in a large portion of Canada. They have a good tolerance for moderate snow loads and they can be used with most roof slopes.

The quality and detail of the shingle work are particularly important in areas where there are severe freeze-thaw cycles because lower grades may become brittle at very cold temperatures.

Metal Roofing

Metal roofs tend to shed snow easily and therefore are an excellent option in areas that experience heavy snowfall. It also tends to outlast asphalt shingles, often through freeze-thaw cycles, and generally gives a longer service life than asphalt shingles, but is more costly.

Installation is critical with metal roofing as the performance of the system over time will depend on the seam, manner of fastening and type of underlayment used. One of the first steps homeowners take when exploring the concept of a metal roof is to research local metal roofing contractors, gaining insight into pricing and installation methods in their locality.

Flat Roofing Systems

Flat and low-slope roofing systems are ubiquitous in additions, garages and many commercial buildings. In snowy climates, the system should also have sufficient drainage and load to cope with the weight of snow and water on flat roofs which cannot shed the load as sloped roofs can.

Quality and integrity of the membrane and the integrity of the seams are especially crucial when there are marked temperature fluctuations.

Regional Differences Across Canada

In coastal British Columbia, the primary issues are sustained rain and moderate temperature, and moisture management and material durability against near-constant humidity are primary concerns.

Heavy snow loads and strong winds combined with significant freeze-thaw activity make the choice of materials that will resist repeated temperature fluctuations and structural strength more important for a home in the Prairies.

The climate in Ontario and Quebec experiences humid summers as well as cold winters, and Atlantic Canada may be exposed to powerful coastal storms. None of this implies that any material is by default bad for any area, but it does imply that the conditions of the area should be given due consideration.

Beyond the Material: Installation, Insulation, and Ventilation

The roofing material is only part of the equation. The insulating and ventilating properties of the roof also have as much influence on the roof performance as the material that covers it, especially in cold climates with ice-damming problems.

Installing an appropriate material without proper ventilation, or combining it with a lack of insulation, won't give the material its best performance.

The quality of the installation also plays a major role in outcomes. The age of two roofs with the same materials can vary greatly according to how they were installed, such as how regularly the roofing system is fastened, how the flashing was integrated and the type of underlayment.

This is particularly the case with metal roofs, as working with expert metal roofing installation contractors can have a significant impact on their long-term performance.

Weighing Upfront Cost Against Long-Term Value

The cost of a roofing system made from asphalt shingles is usually one of the lowest costs of the most common roofing systems, making it available to many homeowners. While the initial investment in metal roofing is higher, it can last a much longer time and could have lower maintenance needs throughout its life.

The cost of a flat roofing system can differ significantly, depending on the kind of membrane and the dimensions of the building. This will depend on the homeowner's intended length of time in the home, budget considerations, and the availability of materials in the area.

By obtaining quotes from a number of metal roof contractors or asphalt specialists, depending on the metal roof material being compared, it will be easier to get a feel for realistic costs when it involves a specific property and area, as opposed to more general quotes that may not be reflective of the local area.

Frequently Asked Questions

In Canada, is the increased cost of metal roofing worthwhile?

This depends on the priorities of the property and homeowner. Metal roofing can be more durable and will withstand snow and freeze-thaw conditions more effectively than other materials, but the initial investment is higher and must be compared to the length of time the roof will be in use.

Are asphalt shingles not up to the job in cold Canadian winter weather?

Not necessarily. The quality of shingle products widely ranges and in cold climates, as much as the product itself, proper installation is important.

What is the impact of the roof's pitch on the selection of materials in snowy areas?

A steeper slope will shed snow better, thus relieving the roof of its load. The roofs in a flat roof building should be more robust and have better drainage to cope with snow and meltwater.

Is it not an ill idea to build flat roofs in snowy Canadian climates?

Flat roofs can be successful in snowy areas if they are properly designed, installed, and provide for adequate drainage and structural strength, but must be carefully planned as opposed to sloped roofs.

Is the coast vs. interior divide more important than the provincial boundaries?

Often, yes. Unlike provincial boundaries, climate factors are more dependent on geographic characteristics such as coastal areas and altitude. This means that two sites within the same province can have different roofing needs.

What is the average service life of asphalt shingle roofs in Canada?

It depends on the quality of the product, the installation, and local climatic factors, so it's best to refer to the manufacturer's specifications and ask a local roofing professional for an accurate quote for your property.

Should insulation be considered for upgrading when a roof replacement is being done?

A good time to evaluate insulation and ventilation is during roof work; however, it is important to consider the conditions in the attic before making a decision on upgrading.

Disclaimer

The value of the material, the cost of installation, and the anticipated service life will vary with region, supplier and project application. Actual performance will vary based on installation quality, maintenance and weather.

Warranty issues will be based on the specific materials, manufacturer, contractor and installation used.

Find the Right Material for Your Property

No one roofing material is ideal for every Canadian property. The decision depends on the local climate, the building's construction, and length of time the owner intends to live in the residence.

You can contact Renewable Roofing Solution for evaluations of what roofing material is ideal for your property. Please review renewableroofingsolution.com or give us a call at (502) 664-8006 to discuss your options.