The recent snow and ice storms we have may mean you can have some fun with that new snowmobile you purchased last spring, but they take their toll on your roof. Snow build-up on your roof is common this time of year. It is to be expected. However, when we have large accumulations of snow like we have had recently; special attention to your roof is needed.
A roof, no matter if it is sloped or flat, on a residence, or a commercial building, is designed to withstand certain amounts of snow accumulations. The amount varies from city to city around the country but is based on the average snowfall the area receives. Engineers use their knowledge and expertise to design buildings to withstand certain amounts of snow accumulation. If they didn’t, building collapses would be commonplace.
What can happen with an excess buildup of snow?
An excess buildup of snow can have several side effects on a building’s roof. Let’s take a flat roof, for instance. Flat roofs, as found on many commercial and industrial buildings, as well as homes, contain pipes, vents, and other objects that protrude through the roof. Excess snow accumulation on these roofs may cause these protrusions to become blocked and render them inefficient. Something like vent stacks for a sewer can have very dangerous effects inside the building when excess gas is not allowed to escape the building. Toxic gases can buildup inside and cause illness or even highly explosive situations.
Vents for attic and exhaust ventilation, are required to remove excess air from within the building and attic space. These being blocked due to snow mean that the air, which is oftentimes warm and moist, has no place to go and stays inside the attic space. This allows the moisture to infiltrate the structure of the roof and causes rot, which leads to very expensive repair work or even total replacement in extreme cases.
Other problems arising from excess snow accumulation is weight. Snow is heavy. If you have an older home, oftentimes the plywood is thinner than used on new construction, and the roof structure itself may be rotted in spots. A flat roof can have the same type of problem as a sloped roof. Accumulation of six inches is not usually a problem, but when the snow starts to get a foot deep or more, then you should become concerned.
What other problems does snow accumulation cause?
A buildup of snow on your roof can cause hidden problems. If your roof is not properly vented and sealed to prevent heat-loss, the resulting warm air that infiltrates to the attic from below warms the upper areas of the roof which causes snow to melt and run down to the lower edges and freeze. This creates a buildup of ice on the roof edges. This is called an ice-dam. The ice dam is what creates those pretty icicles hanging from the eaves of a roof that so many people like to look at. A roof with icicles means a roof with problems.
Ice dams cause gutters to tear off, shingles to become loose and allow water to penetrate into the interior of the building causing damage to the drywall, paint and flooring. Some people will tell you to chisel the ice from the roof, and the problem is solved. This may stop the water backup but in no way does this solve the problem. If you have an excess amount of snow on your roof, the best way to prevent problems is to have a professional, experienced with roof repairs, to come out and remove the snow before it can create an ice dam. Do not attempt this yourself. The results are often tragic as the roof is slippery when covered with snow. Leave it to a professional.
Some other solutions to help the problem of ice dams proper attic ventilation and/or increasing the insulation in your attic to prevent excess heat loss. If you roof is being repaired or replaced, have the contractor install an ice shield. It is a rubber membrane that helps reduce the chances of water backing up under the shingles. The installation of heating cables is yet another option. These heat up the area around the edge of the roof and melt the snow, preventing the buildup of ice. All these options should be first discussed with a roofing expert who can give you suggestions based on a number of factors, including what the average weather conditions are in your area.
Excess snow buildup is the number-one cause of roof collapses in Canada. I am sure you all remember seeing buildings in the news that have collapsed due to excess snow. The effects are costly to the building owner but when there are lives involved in the collapse, no dollar value can be placed on it. Most roof collapses are preventable when the roof is properly designed and constructed. So what can you do to prevent major damage to your roof from snow?
It would be nice to be able to stop and start the snow at will, but in reality, we have no control over the amount or when snow falls. After a snow storm, most people are concerned about clearing their driveway and sidewalk. When you are outside doing this, take a minute to look up at your roof. Try to visually check the depth of the snow from ground level. If it is getting close to 12 inches deep, or you see that vents or pipes are covered, then you need to have a professional roofer clear the snow for you. Going on the roof while it is covered in snow is very dangerous and ice may have formed under the snow making the roof treacherous. Always have it cleared by someone who is experienced being on roof tops.
Keep an eye out for ice dams forming on your roof also. There is nothing wrong with calling a professional roofer to come and inspect your roof if you are not certain it is adequate for the weather conditions you have in your area. In most cases, inspections are free and can offer-up some really good advice. Why take chances of a leak forming when a simple inspection reveals any potential problem before they arise?