Strong winds have the strength to blow the roof off your building and dealing with roof damage can be a disruptive and costly matter. Low-pressure areas are more prone to severe windstorms and tornadoes. These weather conditions produce high winds and rain that can damage your roof and disrupt your business operations. But property damage from high winds can occur in any geographical area, even if it doesn’t occur often.
We’ve compiled some best practices to help protect your building against roof damage from high winds.
Roof design and construction
It’s important to choose the appropriate roof design and construction specific to your operations for stability, durability, and damage resistance in high wind areas.
Roof pitch refers to the steepness and angle of roofs. Commercial buildings generally have either flat roofs, low-slope roofs, or steep-slope roofs, residential apartments and office buildings tend to only have flat roofs, and residential homes are commonly seen with steep-slope roofs.
Here are some common roof constructions that you may want to consider:
- Built-Up Roofing (BUR) membrane – This is composed of layers of roofing asphalt and asphalt felts which are installed so that multiple interwoven plies form a roofing membrane.
- Metal roofing – A metal roof is a roofing system made up of metal pieces or tiles. Metal roofing is a popular commercial roof type because of the various metal materials available.
- Modified bitumen (MB) roofing – MB is asphalt-based and designed for buildings with flat or low-slope roofs. It is made of asphalt combined with polymerized rubber or plastic, then reinforced with fiberglass to create a rugged yet flexible waterproof membrane.
- Thermoset roofing membrane – Thermoset roofing membrane is an extremely durable synthetic rubber material widely used in low-slope buildings.
- Green roofing – Green roofs may be the most versatile kind of commercial roof available. A green roof is a layer of vegetation planted over a waterproofing system that is installed on top of a flat or slightly sloped roof.
How do high winds blow off roofs?
When high winds travel over your roof, it creates a low pressure in the atmosphere. The pressure around your roof is lower than the atmospheric pressure below it. Concurrently, when air currents enter your building from an open window or door, it creates pressure inside that causes an upward thrust of air. This suction effect causes the roof to lift and blow off in the wind. The pressurized air inside your building is combined with the powerful force of wind pulling on the outside to lift your roof off. This is known as Bernoulli’s principle.
Ways to prevent roof damage
- Ensure the roof is installed according to code
This is particularly important with older roofs because a previous owner may not have hired a reliable, licensed roofer. - Seal your roof
Ensure the edge of the roof is sealed with a roofing cement to prevent gale-force winds from penetrating underneath. In addition, make sure the roof decking is also sealed. - Install windproof sheathing
When installing a new roof, make sure that the sheathing is windproof. Roof sheathing is the second line of defense against heavy winds. - Maintain your roof coverings
Inspect the roof regularly for cracked, worn, curled or missing roof coverings, as well as signs of water damage on the underside of the roof. This will help reduce the risk of having your roof blown off due to deteriorating components. Replace the roof as it approaches the maximum lifespan for its roofing material. - Maintain your roof supporting frame
Inspect the structure regularly for cracked, worn, or rotting trusses and rafters. Also regularly inspect the supporting frame. - Fix what is broken
Keep your property well-maintained by addressing issues like loose fence boards or peeling roof shingles—taking care of small problems early can help prevent more extensive and costly damage during a windstorm. Repairing things in advance is usually far less expensive than fixing storm-related damage afterward.
If a storm is approaching and time is limited, inspect your property for anything that needs attention and try to make temporary fixes. This can help prevent loose parts from breaking off and becoming dangerous debris. - Add roof/hurricane clips
Roof/hurricane clips are galvanized steel clips that attach your roof to the rafters or trusses of your building to protect the roof from blowing off in severe weather conditions. There are different uplift protection strengths of these clips, so select your clip strength according to your local wind danger. Local wind danger can be calculated using the Government of Canada’s Wind Load Calculator for roof cladding and vegetated roof assembly. - Trim tree branches
If you have trees near your business, overhanging branches can pose a serious risk during windstorms. They can scrape against your roof, lift shingles, damage gutters, vents, and flashing—making it easier for rain to get in and cause interior damage. Trimming branches back before a storm hits helps protect your roof and can save you from expensive repairs later. - Rope your roof down
For smaller commercial low-rise buildings, if a windstorm is predicted to hit your building, anchor your roof tightly in place by holding your roof down with a system of ropes. The ropes are attached at opposite ends of your building to concrete blocks on the ground.
What to do after high winds or storms?
After a storm, it may be difficult to identify the severity of damage done to your roof, especially if you are only inspecting from the ground. Inspect and document as much as you can from a safe distance. Your roof may have minor abrasions, loose components, areas missing asphalt, and detached cladding or other detached roofing materials. Fallen objects or debris from affected trees and powerlines may have damaged your roof as well.
Hire a licensed and professional roofer to inspect your roof, especially from an elevated angle. When it is safe to do so, clean up debris from your roof and yard. Check inside your building for leaks, wall discoloration, and other damages.
How to inspect your roof for wind damage?
1. Look for dents and dings
Start by checking the surface of your roof for visible dents or dings. These may be signs of debris impact caused by high winds and can weaken roofing materials over time.
2. Check for cracks
Inspect shingles, tiles, and other roofing components for any cracks or fractures. Even minor cracks can compromise the roof’s protective barrier, increasing the risk of water intrusion and long-term damage.
3. Identify loose or missing materials
Examine the roof for any dislodged or missing components such as shingles, flashing, or sections of guttering. Strong winds can tear these elements loose, creating vulnerabilities that may lead to leaks or structural damage.
Common signs of wind damage
Bruised shingles
Shingles with bruising or indentations are clear indicators of impact damage from flying debris or wind-driven objects. These blemishes weaken the shingle layers and reduce their effectiveness in protecting your roof.
Granule loss
Excessive granule loss on asphalt shingles is another telltale sign. When granules wear off, shingles become more susceptible to UV rays, which can accelerate aging and reduce their resistance to wind and moisture.
Water leaks and interior stains
If you notice water leaks or moisture stains inside your home, it may point to wind-related damage such as lifted shingles or compromised flashing. These issues can allow water to seep in, potentially leading to interior water damage and mold growth.
Ensure that you’re protected with commercial property insurance
Despite your best efforts, sometimes things can still go wrong. That’s when insurance can be helpful. To learn more about how a tailored policy can help protect you, your employees, and your bottom line, visit our Commercial property insurance page.
This blog is provided for information only and is not a substitute for professional advice. We make no representations or warranties regarding the accuracy or completeness of the information and will not be responsible for any loss arising out of reliance on the information.
