House roof, snow, ice & warm weather.

[PopeyeFAFL]

Here in Montréal, we had 2 severe snow storm that left a decent amount of snow on roof.Now, today the weather was few degrees above the freezing point (7°C), even raining (10 to 15 mm of water).Some newspaper suggested to remove the snow from the roof (at least making sure the rain gutter path is clear).Now, my question, for someone who know a bit of the building code (in area where snow is usual):1- If you have a properly built roof with the first 6 ft of glue membrane, with a steel edge inserted before the rain gutter and proper ventilation, do you need to worry? (even if the snow, due to wind, is slightly over the rain gutter).2- What could be the typical "snow factor" (amount of snow + ice, converted in feet of snow, that a normal individual house is design for), I guess they even add wind factor on top of that.I saw, maybe 2 to 5 % of people clearing their roof, ok they may not have to worried, but is house not design for few days of warmer weather (with even a bit of rain) during winter.Thanks in advance.

[scherry2]

I'm not an expert. I wouldn't think it would be the weight,(but it would be something to worry about) i think it would be the water and Ice over long periods backing up under the shingles and possibly leaking. Myself, if its any unusually large amount of snow I would be removing it. I've done it many times for my parents in Wisconsin.

[vibe-04]

I hear your delimma. Ottawa has a lot of snow as well. i think it sounds like your roof is ok with the membrane and if you have a steep grade. Snow removal is more a problem for bungalos (single story) houses where ice dams can build up. I don't have the stats on the snow/ice factor. If your roof is well built, you should be OK. Check your gutter drain off to ensure the water flows away from the house not towards the house (I have to check myself). Check your sump pump to make sure it is working. Also look for pooling and give the water a path to drain.What ever you do, DON'T GO ON THE ROOF.You can get special roof shovels with extra long poles or hire somebody.

[Raven]

I don't know the building codes and stress factors, I'll leave that to the engineers. I do know that the 3 roofs I shovelled in the last few days had many, many tons of snow on them. I shovelled one today as the rain started coming down and it had about 70cm (28 inches) of wet snow on it and 6-8 inches of ice on the eaves. Roofs will withstand a lot of weight but the flatter they are the more prone to collapse they become. I've seen the result of a collapsed roof and it's not pretty. Use common sense and don't take any chances. If it looks scary, get it shovelled. It's a lot cheaper than rebuilding your house and replacing the contents which are water damaged.

[Mavrik]

yeah... +1 on the weight comments. wet packed down snow causes structure damage.

[chevelle_lover]

I do not know about codes since everyone is different depending on the area. A quick rule is that if the snow is deeper than that of 18" then it should be removed. If you go to Home Hardware, Home Depot or Rona then you can get a roof brush. It is just a stiff bristle broom or rubber rake that is on a pole similar to a pool skimmer. You then can pull the snow off. Just be carefull not to damage your gutters.

[jimincalif]

What's snow?

[Whelan]

Light snow is not so bad, but over time as the temp goes up and down it melts, then refreezes on the lower layers turing into ice and causing stress on structures. Roof collapses are not hugely common (at least from what I know) because they are so well designed to begin with. The A-frame styling is very sturdy dispersing weight across rather than all in one spot. Clearing off a roof is not a bad idea. I know they actually make roof shovels so you can stand a good distance from the house and rake it off. The plus side to having light snow for a little bit is the added insulation, saves on energy costs.

[Sputnik]

We removed the snow from our roof. We used a snow roof rake - bought it at crappy tire a couple of weeks ago (I guess they are sold out now). We do have ice dams as well on the roof and we were concerned about the rain backing up and coming in under the shingles. We had friends check our house while away at xmas and they reported no issues. Most people on my street removed the snow (all townhouses about 10 years old).