Under normal winter conditions and as long as there have been no modifications to the building structure, you probably don’t have to worry about clearing the snow from the roof of your home.
Both flat and sloped roofs are, in principle, built to withstand the snow loads that can be expected in specific regions of the country. For proof, you need only look at houses built several decades ago – after all, their roofs have stood up to all those harsh winters of years past.
You do need to be more vigilant, however, when there are unusually high snow accumulations – especially if there is a later thaw, or a period of freezing rain. Under such conditions, the snow load will be considerably heavier, and ice may form, impeding the normal draining of your roof.
Keep your eyes and ears open
At what point should you be worried about structural weakening or water infiltration, and clear snow from your roof as a preventive measure?
First of all, an overloaded roof will very probably start sending out “calls for help.” This means that in critical periods, you must be alert to such warning signs as unusual cracking sounds, warping of a ceiling, cracks appearing in wall and ceiling plaster, or doors starting to jam.
If these signs of stress are present, then you should take preventive action.
Take control of the situation
Be very careful, however: clearing snow from a roof is delicate work. Make sure to use wooden or plastic tools, without sharp points or cutting edges.
Not to mention the fact that working on the roof involves the risk of falls or even electrocution – so it’s highly recommended that you entrust the job to a roofing specialist who has the required skills, experience and equipment. Note that if your roof is still under warranty, you must first call the contractor who provided the warranty.
Also, there may be no need to clear all the snow from the roof. This depends on the type of roof: with a flat roof, you need only make sure the drain is clear and then open drainage paths that converge toward it; on a sloped roof, make drainage paths to ensure that water can run normally down to roof edges.
In either case, the bottom layer of snow must always be left in place to prevent damage to the waterproofing membrane. Also, make sure snow doesn’t obstruct the plumbing vents and the roof vents, which on a sloped roof help to ventilate the attic.