No magic number
In its press releases, the Régie du bâtiment du Québec (RBQ) gives no depth and no weight at which a roof should be cleared.
The same depth of snow can be light or very heavy depending on what it has been through. Two roofs on the same street do not carry the same load. Their design, age and condition differ.
The RBQ points out that roofs are built to carry winter snow loads, but that the weight can create unusual stress. Roof snow removal is not booked by the calendar. It is decided by looking at the building, the weather and the snow.
First marker: what the house shows you
The RBQ names four signs of overload.
- cracks in interior walls
- interior doors that stick or rub
- unusual cracking sounds
- ceilings that sag or change shape
If such signs are observed, the RBQ recommends clearing the roof, whatever the amount of snow. The sign outweighs what you see outside.
When you see a sign, move away from the area, have the roof cleared and have the building examined by a structural engineer. If the danger is immediate, get out and call 911.
Second marker: the weather of the past few days
According to the RBQ, alternating rain and snow makes snow denser and heavier. Montreal winters often bring rain and snow back to back.
Pay closer attention after:
- rain falling on a roof already covered in snow
- a thaw followed by a return of the cold, which turns wet snow into a crust
- several snowfalls close together with no melting in between
Packed snow can even look lower from the ground. That same snow can weigh more.
Third marker: where the snow piles up
Snow does not settle in an even layer. Wind moves it, and a roof can be almost bare on one side and heavily loaded on the other. From the ground or an upstairs window, look at:
- the base of a taller wall, like the neighbouring triplex that rises above your duplex
- along the parapets of a flat roof
- the valleys, where two roof slopes meet
- the low roof of an addition, garage or carport, which catches snow falling from the roof above
You make all these observations without going up.
What we look at before going up
We ask the same questions. Is there a sign inside, what has fallen lately, and where has the snow gathered? On a flat roof, a drain buried before a rainfall weighs heavily in the decision.
Frequently asked questions
Should you clear your roof after every storm?
No. Roofs are built to carry winter snow loads, the RBQ points out. Roof snow becomes a concern when a sign appears, when rain makes it heavier or when it builds up unevenly.
How much snow on a roof is too much?
No depth applies to every roof, and the RBQ does not give one. The RBQ asks owners to watch for signs of overload. Only a structural engineer can tell what your roof can carry.
Can I go up to check how much snow there is?
No. Look from the ground, from a window or from inside, and take photos. If you still have doubts, write to us through the form and describe what you see.
Official sources, consulted October 8, 2026: