Harsh Winter Commercial Flat Roof

Harsh Winter Weather For Commercial Flat Roof

In the Greater Toronto Area (GTA), flat roof damage is a common effect of the harsh winter weather for commercial flat roof and residential flat roof properties. It is important to understand these factors and how to minimize any future damages.

How Weather Conditions Affect Your Roof:

Sudden Changes in Temperature

Temperature change creates icicle

Toronto winters consist of warmer days with extremely cold nights, causing flat roofs to undergo potential thermal shock. Typical flat roofing structures are made to expand in warmer temperatures and contract in colder temperatures. Over time, the expanding and contracting performance of your flat roof system will generally decline.

Signs of damage include but are not limited to:

  • Joints cracking
  • Separation of flashings
  • Loose seams
  • Splits in the flat roof and/or materials


roofing winter hazards

Heavy snow is a common occurrence in the Greater Toronto Area, it is important to note that too much snow will have a negative impact on your roof. While there are various types of flat roofs built to withstand heavyweight, depending on the size of your roof, too much built-up snow can cause damage.

Important signs to look for:

  • Popping sounds
  • Indications of warped wood
  • Metal supports visibly sagging

We do not recommend attempting to shovel or clear snow from your roof as this usually causes more harm than good.


roofing winter hazards

Ice is a common issue for roofs as it often causes damage to the drainage system and can cause the gutters to collapse due to weight build-up. Winter ice can take the form as either ice dams or icicles, both of which are harmful to commercial flat roofs and residential roofing structures.

Ice damage can result in:

  • Further expanding existing cracks and issues
  • Collapsed ceilings
  • Weakening of the walls
  • Warping of gutters, scuppers and downspouts
  • ‘High leaks’ due to ice backup


Although many commercial buildings use flat roofing, which is known to be sturdier than pitched roofs against strong winds, there is always a chance of wind damage. Wind can carry debris across your roof which over time will cause damage to the membrane structure. When a roof is poorly installed or not prepared for intense weather conditions, wind damage can result in moisture getting trapped underneath the roofing materials. This will eventually lead to water leaks.

The best way to prevent any costly damage is to ensure that all of your roofing is up to date and has received proper maintenance before the winter.

If you suspect any type of damage to your roof during the winter season, it is best to source and repair it as soon as possible to avoid any further problems. Delaying repairs will cause the damage to worsen and will cost you more money in the long run.

Benefits of getting your roof professionally inspected before the first snowfall:

It is ideal to conduct roof service during the warmer seasons as it will save you both time and money. The cold weather negatively affects the performance of materials being used: adhesives are less effective and asphalt products become more brittle.

  1. Ensuring that there are no debris blocking the drains, gutters or scuppers;
    • A blockage of debris provides no escape for melted snow and ice to drain, resulting in possible back-ups and water damage.
  2. Finding proactive maintenance items. Many roof elements can be serviced before they become leaks;
    • Cones, stacks, vents, pitch pockets and other penetrations require re-sealing from time to time
    • Detecting broken seals on skylights, mechanical units etc
    • Loose seams, membrane failure and damaged expansion joints
  3. Ensuring no hazards are present
    • Loose metal flashings, damaged or broken mechanical components such as access doors can be hazardous to people and property, particularly in high wind events

In Conclusion

Recognizing and planning for harsh winter weather for commercial flat roof can save you financially.  Give yourself peace of mind by engaging the professionals at Guycan Roofing today.

Content written by Alyssa Harilall