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Shovel Your Roof Or Not To - Experts Say Not Yet

By 250 News

Saturday, January 10, 2009 11:44 AM

Prince George -    Home builders in the city say that unless we receive a lot of rain in the next few days the snow load on people’s homes in Prince George does not need to be shovelled.

Joe Myatovic of Myatovic Construction says suggesting that you go up and shovel your roof gets a lot of old people thinking it has to be done and they go on the roof, if their shovelling and fall off into the snow bank that’s one thing but if they land on a fence, the Barb-Q or something else that’s a totally different matter.

Myatovic says I own one of those cheap COSTCO green houses with plastic on it and it’s still okay out there in the yard. ‘”It isn’t built like a house”. The last time we had a roof collapse it was about 10 years ago and that was a carport that wasn’t properly nailed up when it was constructed, so take it from there.

If you were going to shovel you need a safety rope, proper gear to move the snow and it is a big job. Think about it,  he said, ‘when was the last time that you seen a house collapse from a snow load in this city”. We have had more snow in other years and until we get there no need to shovel.

Bruce Nyberg of Ebb Construction echoed the remarks of Myatovic, Both men have built more than 200 homes in the city and say the snow load so far is a light snow and unless we get a lot of rain on the roof it’s built to take the load.

Martin Gomes, Of Gomes Construction says he likes to error on the side of caution, "If the snow blows and builds up more on one side of the house than the other you can get a problem because the weight isn’t equally spread. We build houses to carry a 50 lb per square foot load up to 80lbs per sq ft. If you think it’s too much then shovel it" he says.

Wayne Ward of Northern Capital Wood Products said, “I read the story and I’m not shovelling my roof”.

If we get a lot more snow and we get a lot of rain like they say we may get,  then you can have another look at it. If you have an older home, different kind of roof  and your worried,  have someone look at it for you, but just don’t get up on the roof right now and start shovelling.

Other than Gomes every other contractor we contacted to ask whether you should shovel your roof said unless it’s a really old home, flat roof maybe , or a bunch of pitches to the roof , especially if your home is fairly new, leave it alone.

Bill Rushton, who has been building or doing work on homes for over 50 years, says there is not enough snow in the bowl area to shovel them off.

Rushton, who lives in South Fort, says there is about 14 inches of snow on the roofs in South Fort, hardy enough to worry about. I’m not going up there to shovel he says.

Unless you get blowing snow that makes the snow build up more on one side of the home then the other there is no problem so far this year and you don’t shovel the roof just because it might snow or rain .

 

You need proper gear to do a roof and unless you want to go out and get a special snow scoop, harness etc. Don’t do it.

If it rains a lot they say then go back and look at it later , we have had a lot more snow on your roof in the past  without any roofs collapsing so why now.


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Comments

mackenzie a few collapse a lot of wind blow if I wait for the rain It might be to late
Exactly. The Citizen was reporting this morning that we should all be up on our roofs shoveling, which is first of all not necessary and secondly dangerous.

People have some really short memories if they think we have lots of snow right now.

I read that article in today’s Citizen and could not believe it. They should have done thier homework first. Maybe get opinions from structural engineers. How much does this snow weigh? The article is going to scare people onto their roofs where they could actually damage the roof or fall off. If the snow was wet and heavy it should be moved in layers so as not to overload one side of the truss. Hopefully no one will be silly enough to follow the recommendations of the Citizen.
I agree that there is no need to shovel yet. I always check with the professionals because it is a huge job and it is easy to damage a roof by a poor shovelling job.
I find it funny how the article takes several shots at the Prince George Citizen, and then reads as if it was written by an 8th grader. I am not surprised that there is no name attached to it considering the quality of writing.

1. "... gets a lot of old people thinking it has to be done and they go on the roof, if their shovelling and fall off into the snow bank..."
2. "‘when was the last time that you seen a house collapse from a snow load in this city”."
3. "more on one side of the house then the other..."
4. "different kind of roof and your worried,.."
5. "flat roof maybe, or a bunch of pitches to the roof"
6. "more on one side of the home then the other there"
7. "so why now."

Errors
1. they're not their
2. 3 mistakes in one sentence: two forms of quotation marks for one quote, the quotation marks need to follow the period and not come before it, "that you seen" is awkward.
3. than not then
4. you're not your
5. awkward, maybe add "have a bunch"
6. than not then
7. Questions need a question mark.
im shvling mighn off bbefore it colapses. think i be on the safe side before it ranes.
I can’t see where Opinion250 even mentions the Citizen, can you Smooth? Opinion 250 took the time to talk to the experts, those who build the homes and that’s good enough for me. For you Smooth , shoot the messenger , not the message right?
Actually the people quoted are expert builders. They build to drawings and specifications prepared at the least by a technologist for homes. Those are all done according to standard tables and calculations based on roof configurations. None of them are structural engineers. They are very rare in this town.

Each home is different. Some have trees close to them other have roofs lower than the main ones which can gather drifting snow as was mentioned, as can portions of roofs adjacent to large evergreen trees.

Then there are dormers, valleys, etc. etc.

Here are some basic calculations for thsoe who might be interested in how critical the situation is. Sorry for the length of the post.

One inch of water weighs 5.2 lbs per square foot. A rough calculation is that 1” of rain precipitation is 1/10th of snow precipitation or 10” of snow. That is the same as a water content of 10%. A very dry snow, the kind that falls on very cold days, can have a water content of less than half of that. Wet, heavy snow, the kind that falls at around the freezing point, can have a water content of about 30%. Add rain to dry snow, two things happen, there is more water content since the rain is typically absorbed by the snow. The snow also starts to collapse and the depth is reduced. An inch of precipitation in a 24 hour period in PG is unusual at any time of year. So that would add 5.2lbs of load.

The other thing that happens is that there is a heat loss from all roofs. Those that have well ventilated attic spaces, which is rare even when standards are followed, will have less heat loss at the roofing surface. Since snow starts to melt with heat, a deep snow on the roof will eventually reduce in depth due to heat loss as well as sublimation – direct change from snow to water vapour.

Look at a few properties with houses and free standing sheds. Since the sheds are likely not heated, the snow depth on the sheds is typically quite a bit deeper than that on the house. Everything being equal though, the two buildings should have similar weights of snow on them. The house may have less since it is higher and thus, on windy days, more snow tends to be blown off than on a lower building.

Let us, for good measure, assume that the snow on the roof of an average house at the moment is 12 inches deep (that is what they are where I live in the bowl) and that there is a layer immediately adjacent to the roof surface which has a high water content of 50% and is, for good measure, 1” thick. That gives it as weight of say 3 lbs. Then let us give the rest of the 12 inches at 20% water content an average weight of 12 lbs per sf for good measure.
That gives us a snow load of 15lbs/sf. Modern roofs in PG (built since say 1970 about the time when the provincial building code came into being were designed for just under 40lbs/square foot. So, if we get an inch of rain on Sunday/Monday, we are still only at half the design load.

You can calculate the water content of the snow wherever you want on your house or property yourself. Pick a snowy spot. Use a measuring tape to measure the snow depth. Mark a foot square area. Shovel the full depth of snow/ice into one or more containers. Melt the snow and weigh the water or measure the volume of water. I imperial cup of water weighs 10 ounces or 10/16th of a pound. Make sure you use the full depth of the snow since there are a number of layers, each having different water content.

BTW, I am not an engineer, so don’t take my word for it. That part is just simple math.


Thank you Gus, That is the kind of post that I like to read, rather than talking about whom has what story you put it all together. Giving us all an informed opinion. Thanks again
'The Citizen was reporting this morning that we should all be up on our roofs shoveling,'

'I read that article in today’s Citizen and could not believe it. They should have done thier homework first.'

The Citizen wasn't advising, or recommending or even reporting thst 'we should be shoveling.'

They were quoting the City's Building Inspector on the subject - he's the one guy at the City that should know what he's talking about.

In the proud tradition of incompetence at the Development Services department, he doesn't.

I expect the City's legal counsel will recommend an immediate and embarrassing written retraction in the Citizen.

I'd say on Monday - Tuesday at the latest.
"The Citizen wasn't advising, or recommending or even reporting thst 'we should be shoveling.'"

Thanks for the tip, but I realize that. The point is that they printed an article which quoted the City Building Inspector who falsely said we should be shoveling our rooftops.

Hopefully nobody took that article seriously and went on their roof and hurt themselves on the weekend.
Two roofs with about 12 and at most 16 inches of snow on them and no drifts were cleared this afternoon within a 10 house radius of where I live. Both were cleaned down to the shingles over at least 50% of the roof area. Hopefully they will not have any roofing damages.
One neighbour has been clearing for two days so that part is cleared and part is not. This is very dangerous. I think the Citizen should be posting if you can't clear it all, don't play at it.