The signs of a roof overloaded with snow

Snow depth is misleading

None of the official sources consulted for this page gives a depth at which a roof would be in danger. In a March 2023 news release, the Régie explains that when thaws, rain and snow mix, the snow becomes denser and therefore heavier. The same snowbank can weigh more after a winter rain without getting any bigger.

The decision to order roof snow removal rests on what the building shows you, not on a measurement taken from the sidewalk.

Four signs, and how to spot them

Cracks in interior walls. Walk through the rooms and look at the walls and corners. Photograph each crack with an object beside it for scale, and note the date.

Interior doors that stick or rub. Open and close each door. Note the ones that catch, and since when.

Unusual creaking sounds. A digest from the National Research Council of Canada, published in 1968 and kept as a historical reference, notes that ice on a poorly drained flat roof often shows itself through loud cracking sounds on cold nights. Do not use this observation to reassure yourself. From inside, nothing lets you tell that noise apart from the sound of a roof frame under strain. If you hear a creak you do not recognize, get everyone out and call 911.

A ceiling that changes shape. Look at the ceilings from the floor, with light coming from the side to bring out bumps and dips. If a ceiling drops or bulges, do not stay under it. Get everyone out and call 911.

One sign alone, or several at once

The Régie writes that if these signs are numerous, the building must be evacuated and the necessary steps taken to remove the snow, no matter how much has built up on the roof. Its March 2023 news release does not count the signs. As soon as they are noticed, it recommends having the roof cleared.

For a single sign, the Régie gives no separate instruction. In general terms, it recommends consulting a structural engineer to check whether the roof is under stress from the snow load. A single sign does not prove that all is well. When in doubt, get out and call.

Who to call, and in what order

1. 911, if the danger is immediate or if you are unsure: unusual creaking, a sagging ceiling. Get out with everyone first, then call.
2. A structural engineer, to find out whether the roof frame is suffering. Bring your notes and your dated photos.
3. A roof snow removal company, to remove the load, with the experience and equipment the Régie asks for.
4. Your insurer, to notify it and ask what your policy covers.

What you do not do

• You do not climb onto the roof or up a ladder to look at the snow up close.
• You do not go into the attic to examine the roof frame.
• You do not stay under a misshapen ceiling to measure it or prop it up.

Frequently asked questions