Snow load on the roof: when should you have it cleared?
Updated
It snowed three times in ten days, then it rained. From the road, the cottage roof looks like it’s wearing a thick mattress. Should you have it cleared now, or wait? There’s no simple number you can apply by eye: the right answer depends on the roof, the snow, and the signs the house is giving you.
What to check right now
1. Look for signs of overload inside
The Régie du bâtiment du Québec lists four signs to take seriously when a roof is heavily loaded. Walk through the house and look for:
- conspicuous creaking noises;
- interior doors jamming or rubbing against the frame, especially upstairs;
- cracks appearing on interior walls;
- a ceiling deforming or buckling.
Also note water suddenly coming in, or a beam that looks like it has moved.
2. If you see those signs: get out
Don’t stay inside to “see what happens.” If several of those signs are present, the RBQ says to evacuate the building and have the snow removed, no matter how much has piled up on the roof. Keep clear of where the roof sheds and have the situation assessed by a building professional. If there’s immediate danger, such as something giving way, call 911.
3. Look at the roof from the ground
With no signs inside, walk around the house and look:
- is the snow spread evenly, or has it drifted on one side?
- are lower roofs (addition, garage, covered porch) catching snow sliding off the main roof?
- are the valleys, where two slopes meet, packed full?
- is there an ice dam along the edge?
Photograph each side. Those photos let you compare after the next storm.
4. Think about the snow that’s coming
Check Environment Canada’s warnings. Rain forecast on top of deep snow, or another big snowfall, changes the decision. It’s better to have the roof cleared before the next system than after it.
5. Don’t go up yourself
A snow-covered roof hides skylights, edges and ice. The CNESST links roof clearing to falls from height, burial and electrocution, and to snow plates letting go suddenly, especially on a metal roof. The RBQ recommends leaving the job to a properly equipped company, which will also protect the roof membrane.
Why it happens — especially at a Townships cottage
It’s not the depth that matters, it’s the weight. Fresh powder is light. The same depth of packed, wet or rain-soaked snow weighs far more. A layer of ice between two layers of snow adds even more. That’s why you can’t judge a roof with a ruler.
Every roof has its own capacity. Roofs are built to carry the snow loads of Québec winters, the RBQ notes, but that capacity depends on the region and on the code in force when the building went up. An older cottage, a roof extended by hand, a covered porch added later or modified framing won’t necessarily carry what a newer roof can. Only a professional can assess it.
Roof shape changes everything. A steep metal roof often sheds on its own. A flat or low-slope roof holds the snow. Valleys, dormers and changes in roof height create local build-up. Wind drops snow on the sheltered side.
The Eastern Townships combine snow and thaws. On the mountain around Sutton and Potton, big snowfalls are often followed by rain or a mild spell, then a freeze. The snow settles, gets heavier, and an ice crust forms. At an empty cottage, nobody sees the roof change from one week to the next.
Prevention: what you can do, and what belongs to a professional
What an owner can do:
- Know how the roof is built: pitch, roofing material, additions made over the years. Old plans or the seller can help.
- Keep a roof rake to pull snow off the roof edge from the ground: for a sloped house roof, the CNESST finds a telescopic-handle roof rake is very often enough.
- Keep the area around the propane tank and meter clear, since that’s where roof snow lands.
- Book a roof snow-clearing company before winter, rather than hunting for one mid-storm when everyone is calling at once.
- Ask the company how its workers handle working at heights and whether it’s in good standing with the CNESST.
What belongs to a professional:
- Clearing the roof, leaving a thin layer so the roofing isn’t damaged.
- Assessing framing that shows signs of overload: an engineer or building professional.
- Reinforcing framing or repairing a damaged roof: an RBQ-licensed contractor.
In an empty house, how long before anyone notices?
The signs of overload — a sticking door, a creak, a crack — are signs you have to be inside the house to notice. At an empty cottage, nobody hears the framing creak at night. If the next visit is three weeks away, two big snowfalls and a rainstorm can pile up without anyone looking at the roof.
How often someone stops by, and whether someone comes after each big storm, is what lets you have the roof cleared at the right time rather than after damage. If insurance comes into it, conditions vary from one insurer to the next: ask your broker what they expect of you for a cottage left unoccupied in winter.
What we look at on a visit
Every visit, we look at the roof from the ground all around the house: roofing, snow and ice along the edge, uneven build-up. Inside, we check the top-floor ceilings and try every exterior door: a door that rubs or won’t close properly gets noted. We also look at snow piled on the deck, the propane tank and the meter. Every finding is photographed and time-stamped in the report, so you can see the load change from one visit to the next.
If something’s off, we call you the same day, with photos. If needed, we meet the snow-clearing company or RBQ-licensed contractor on site and document the work.