Flat Roof Snow and Ice Removal | Flat Roof Drainage

General Roofing Systems Canada proves roof snow and ice removal services throughout Canada. Calgary, Red Deer, Edmonton, Fort McMurray, Lloydminster, Saskatoon, Regina, Medicine Hat, Lethbridge, Canmore, Banff, Cranbrook, Kelowna, Vancouver, Whistler, Winnipeg, Toronto and points between. British Columbia. Alberta. Saskatchewan. Manitoba. Ontario.

The interesting thing about roof snow loads and ice problems is that homeowners are much quicker to respond than our commercial and industrial customers.

The truth is that commercial and industrial buildings are much more susceptible to roof failure, damage, or leaks than residential buildings.

Commercial Flat Roof Snow and Ice Removal
Commercial Flat Roof Snow and Ice Removal

The main reason for this is that commercial roofs are typically flat and in some cases metal systems.

To exemplify the complications, allow me to refer to a commercial client in Edmonton (bookstore on Whyte Avenue) who we serviced back in 2011. It took senior management hours to figure out how to safely get the ice dams and roof snow on various decks to the ground from that roof because there are so many variables involved. Consider as well that this was a five-storey building. The client, of course, is wondering why the crew is taking so long to begin with removal. The reality is there can be hundreds of variables to consider, check, and recheck prior to starting a commercial roof snow removal project such as this.

Considerations for a commercial or industrial roof can include (as was the case here), and may not be limited to:

Power lines, OHS (Occupational Health and Safety) concerns, pedestrian traffic, vehicular traffic, rooftop equipment of various kinds on different types of roof terraces, ground spotter safety, Bobcats and dump trucks operating, roof membrane considerations, window safety, unbalanced weight loads leading to collapse or significant structural damage, tie-off points, proper commercial insurance, and WCB (Workers’ Compensation Board).

The point here is there are many considerations when removing ice and snow from a flat roof system and far too many people just jump into shoveling off a roof without thinking through what may happen if the process is handled incorrectly.

An experienced flat roof company can also assess your roof while conducting ice and snow removal for any maintenance or repairs that may be required prior to the spring melt, at which times leaks will occur.

There is a Balance between Removing Ice and Damaging Your Roof

Ice build ups at Drains
Ice build ups at Drains

Far too many people, in our experience, desire ice to be removed and do so without considering the consequences.

The equipment and tools used for removal can damage the roof. Hammers, shovels, scrapers, chainsaws, spiker shoes, and de-icers are just some of the examples of what can cause damage to the roof, regardless of how careful you may be.

Ice on a Flat Roof or Low Slope Roof System

When assessing your roof and possible remedies, the considerations are:

  • Is the ice causing a structural problem with my roof?
  • Is it a potential hazard to pedestrian traffic below?
  • Will the ice cause issues with the flat roof membrane when it melts by way of leaking?

The rule of thumb when dealing with the ice on your roof is to do as little as possible and leave what is not going to hurt someone or cause structural failure. Removing dangerous ice overhangs, icicles, and making drainage paths may be all that needs to occur. Of course, if there is a structural concern, then more aggressive action may be necessary.

Most importantly, plan ahead. One of the main problems people have with emergency roof snow or ice removal is that they way too long. It is best to engage a roofing contractor early on to assess and get them active on your life. That way, if emergency services are required, you will naturally be closer to the front-end of service considerations for the contractor as they are already aware and on top of your situation.

The Most Common Solution

In most cases, the ice on a flat roof is dealt with by affecting proper drainage and not through complete removal. Snow can be completely removed, of course, but ice is mostly handled through effective drainage considerations.

Flat Roof Ice & Snow Assessment and Removal Procedures

Industrial Roof Snow Removal
Industrial Roof Snow Removal

As a general guide in Canada, most flat roof systems are constructed to safely hold a maximum of 15 to 20 cm of ice, 35 to 40 cm of hard pack snow (about 70 to 80 cm of fresh snow). If you are getting close to these numbers, or if you have a flat roof or metal low slope roof system that has large roof spans, you will need to lighten the roof load.

The trouble with assessing by depth of snow or volume is that many factors come into play.

  • Who built the roof system?
  • What was the specification?
  • Have there been renovations below? What are the spans?
  • How old is the roof system?

We have seen roof systems collapse that had snow loads under the general guideline above.

Ultimately, if you have a structural concern (look for signs of stress inside the building), contact a structural engineer as soon as possible

Flat Roof Snow Removal

As noted above, there can be hundreds of considerations when removing snow from a flat roof. The man goal, which many folks miss, is for everyone to go home safe and sound. We strongly encourage you not to take on the task yourself.

Flat Roof Drainage and Ice Issues

Ice expansion (later pressure from ice expansions) on a flat roof can cause significant damage to roof top units, parapet walls, flat roof flashing, skylights, elevator shafts, etc. To avoid damage and roof leaks, you can work toward drainage maintenance steps that may help the issues.

The goal is to separate the ice field on your roof from what ice expansion may cause issues with on your flat roof. 

Periodically, as winter progresses, you may have to go to work again at this and separate the ice from the aforementioned sections. Once again, we recommend a professional to take this on for you.

Steps to proper flat roof drainage with ice causing issues (central flat roof drainage systems)

Large Flat Roof Snow Removal Project
Large Flat Roof Snow Removal Project
  1. The first step is to remove the snow from the roof so that the warm roof underneath does not create ice. This is true for both commercial and residential high slope roofs.
  2. Use electrical cables to separate an ice dam or ice field from areas that may be damaged.
  3. Clear about 1 ft. to 3 ft. all around the drain area by using hot water or non-corrosive de-icers. If you really know what you are doing, you can use tools – but be careful not to damage the roof membrane.
  4. Lay the electrical cables (heat wire) starting at the drain and extending to each corner of the roof. Run loops around obstructions in the way such as skylights or rooftop units.
  5. If it is not too cold, the cables will melt their way to the surface of the flat roof giving you pathways for drainage.
  6. Chemical de-icers can be used in the same pattern, but be sure you are using non-corrosive de-icers.
  7. Hot water can also be used to cut drainage paths with some success.
  8. Steam trucks are not considered by most to be an effective method.
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General Roofing Systems Canada (GRS)

24 Hour Emergency Roof Repair: Call +1.877.497.3528 toll-free. info@grscanadainc.com.

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