PRR: yes, I think loads are calculated differently. Not certain what those differences are. But when my roof is certified to handle 120cm dry snow/80cm wet, I am not worried until there's 180 dry or 120 wet on there. Just fairly certain we will get more snow, so it was removed. Do not know how insurance is if you have more snow than the roof is specified for and it collapses... Do not want to find out either.
KaffiMann,
Around here the minimum safety factor is 1.67/1. So your 1.5/1 load is reasonable. I suspect for a roof the safety factor could be 3/1.
When we hang loudspeakers we use 5/1 unless it is portable gear to be gigged by well trained experienced stage hands. Then it is 10/1!
The problem as you are well aware is staying on the roof when clearing it. Not just slipping but the serious issue is wind. Not when it is blowing and you brace yourself for it but rather when it is blowing, you brace yourself for it and then it suddenly stops.
Stay warm, stay safe and all the best cheer when stuck for a bit.
Around here the minimum safety factor is 1.67/1. So your 1.5/1 load is reasonable. I suspect for a roof the safety factor could be 3/1.
When we hang loudspeakers we use 5/1 unless it is portable gear to be gigged by well trained experienced stage hands. Then it is 10/1!
The problem as you are well aware is staying on the roof when clearing it. Not just slipping but the serious issue is wind. Not when it is blowing and you brace yourself for it but rather when it is blowing, you brace yourself for it and then it suddenly stops.
Stay warm, stay safe and all the best cheer when stuck for a bit.
Agree. I have fallen off a 9' roof to a 3' snowbank, that was enough for me.
There is a way to estimate snow load, assuming a semi-steady moisture pattern. Maine gets 3 inches of rain a month. We may get 3 feet of snow in a month but it works out to 3 inches liquid water. On that assumption we get 15 pounds per square foot per month. If it all stayed frozen (sagged, but not run off) we could have 60 psf in our four prime snow months.
Averages don't hold. This summer we fell 5 inches shy on rain. This winter has been up. If we assume this balances we could have 18" equivalent water, 90psf.
Here on the coast, we don't keep snow all winter. There is usually a thaw. Now in mid-Feb, we have had our 24" snow, and it's down to 4" on the ground, 1" on the flat gambrel roof, and none on the steep pitches. (And that plastic chicken-shack roof shed its snow about as fast as it fell.) Taking two bad months between thaws suggests 12" water, 60psf.
And unlike steel or high-tech wood, plain lumber is allowed short-term overload because it fails gradually.
We did have a roof collapse here long ago (before my time). That chicken shed was raftered with spruce 2x6 spanning 9 feet. It fell. Glen re-framed with the same rafters (and a few spares) but at a slightly steeper pitch (maybe 1:9 steeper). You could see the hack-work. That roof lived 30 years. Finally the corrugated tar-board got rotty (as it had on the garage), we had a slack week, and I re-framed in good 2x8 and the plastic.
We got even more snow now, there was ca 25 cm coming down 'couple days ago, yesterday was all clear, now it's going on again, looks like it might be another 20-35cm kind of thing. Not going to complain about it, last winter was really boring with hardly any snow at all. And it's warmer when the snow is here, not so much -20-25c wind blowing hard. Mostly -2 to -10 which is very nice, stable weather.
They say that summer is much better after a snow heavy winter. I certainly hope so, last summer was crap. 15c for the most part.
...Wondering how my mini-glacier project will turn out.
Edit:
Regarding snow to water conversion: That does not work, you forget to include the sublimation process. If snow thaws to 3" of water the snow may have contained +30% to maybe even double that.
Edit:2
Found another source for snow weight on roofs/roofies/rooves, apparently if the roof is certified to handle 1,2m of old but dry snow (slightly compacted, not the fluffy kind) it means the weight tolerance is 350kg per m2.
They say that summer is much better after a snow heavy winter. I certainly hope so, last summer was crap. 15c for the most part.
...Wondering how my mini-glacier project will turn out.
Edit:
Regarding snow to water conversion: That does not work, you forget to include the sublimation process. If snow thaws to 3" of water the snow may have contained +30% to maybe even double that.
Edit:2
Found another source for snow weight on roofs/roofies/rooves, apparently if the roof is certified to handle 1,2m of old but dry snow (slightly compacted, not the fluffy kind) it means the weight tolerance is 350kg per m2.
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Boring can be good.
We have a saying. It only warms up to snow. (In fact: cold and dry hardly snows, it snows when a clump of warm wet Gulf air bumps into the cold air.)
True. Though that is a slow process and it is possible the roof will collapse before the water goes away. Worst-case, COLD all the time (when not snowing), sublimation will be small. In general, we can't know all the factors, and peak snow may be FAR above the average. I tend to ignore small "in my favor" factors in light of the large uncertainty. Simon's stadium-builders will use sharper pencils and deeper data.
770lbs/10.77sf.... 72 pounds per square foot. Right near what I design for.
I found a much better snow-map than any I have seen.
Medeek Design Inc. - Snow Loads
http://design.medeek.com/resources/images/ASCE7-10_FIG7-1_COLOR.jpg
ASCE Ground Snow Loads
I am 500 feet north of the neat line dividing 50 from 60. I have another house halfway between 60 and 70. I don't take this too literally: there can be large differences just across the bay.
There's a LOT more to a full calculation. Exposure Factor, unbalanced load, ice-dam, risk category, surface type.... altogether, 60lb/sf ground load comes to 68lb/sf on my (planned) new roof. (Metal roof instead of asphalt comes to 47lb/sf, hmmmm.)
I am astonished how much of the USA is low snow load. Ohio, Missouri... all that and south is 20lb/sf, which is about what you allow for a worker on the roof. No special consideration for snow!
OTOH, a couple I know were married (before my time) in Missouri in January, and they had to chip the ice off the church door to get wed. A lot of that land can be brutal in winter. But apparently not-so-bad on the roof.
The "blank" zones vary widely. One place may be 10 feet deep and the other side of the next valley hardly gets snow. Oregon shows 10lb/sf where people are, but I know the mountain passes have snow-poles 15 feet high.
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I woke up this morning to a cat squeal and I checked up on my pet bunny rabbit. I saw nothing afoot so I gave her some more hay from the bag.
I noticed it was chillier than usual. Anyway I went to the front door and opened it up and its raining...
Just yesterday it was so hot I had to have the aircon on until about midnight. Now its so cold I have to rug up with a sheet.
I noticed it was chillier than usual. Anyway I went to the front door and opened it up and its raining...
Just yesterday it was so hot I had to have the aircon on until about midnight. Now its so cold I have to rug up with a sheet.
It's cold today.....NOT!
This winter has had a lot of first's including the first time I have seen 17 consecutive days below freezing, which brought a $622 electric bill.
Last week brought cold, snow, ice, and rain, which brought flooding that hasn't receded yet. The Ohio River flooded its banks, and backed up into several creeks.
Today? Well it's break time......
Last night all of the weather forecast's mentioned that today would be warmer, gloomy and overcast. One mentioned the possibility of near record warmth.
This morning I noticed the absence of cold when I set out for the gym at 7AM. When I left the gym around 8 the sun was shining from a clear blue sky. By 10 AM it was 60 degrees. The TV guy said that the record temp for the area on this day was 68 degrees. I spent most of the day outside. When I drove over to the hospital and Walmart in the afternoon I saw two convertibles driving with their tops down. People were out walking, even skating down the main street. WTF, this is mid February. When I got back home I took this picture of the local weather on my iPAD. I guess that 68 degree record got shredded.
Unfortunately that pleasant summer day in the middle of February is over, now back to your regularly scheduled crud!
This winter has had a lot of first's including the first time I have seen 17 consecutive days below freezing, which brought a $622 electric bill.
Last week brought cold, snow, ice, and rain, which brought flooding that hasn't receded yet. The Ohio River flooded its banks, and backed up into several creeks.
Today? Well it's break time......
Last night all of the weather forecast's mentioned that today would be warmer, gloomy and overcast. One mentioned the possibility of near record warmth.
This morning I noticed the absence of cold when I set out for the gym at 7AM. When I left the gym around 8 the sun was shining from a clear blue sky. By 10 AM it was 60 degrees. The TV guy said that the record temp for the area on this day was 68 degrees. I spent most of the day outside. When I drove over to the hospital and Walmart in the afternoon I saw two convertibles driving with their tops down. People were out walking, even skating down the main street. WTF, this is mid February. When I got back home I took this picture of the local weather on my iPAD. I guess that 68 degree record got shredded.
Unfortunately that pleasant summer day in the middle of February is over, now back to your regularly scheduled crud!
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Almost forgot actually had to use the airconditioning while driving yesterday. AC in February!
I am taking advantage of the weather by not just turning off the heat, but also opening all the windows. (Made potato pancakes and the house really needed the airing.)
Propped the door at the office and turned on the paint booth exhaust fan.
Might be in my mind, but I think fresh air feels and smells better.
I am taking advantage of the weather by not just turning off the heat, but also opening all the windows. (Made potato pancakes and the house really needed the airing.)
Propped the door at the office and turned on the paint booth exhaust fan.
Might be in my mind, but I think fresh air feels and smells better.
My energy bill for the past month (midmonth billing cycle) was $138 and that is for electric+gas.
Your house must have no insulation. Mine was built in the 50's (original windows) and doesn't have much insulation compared to modern homes. Minnesota is on average something like 15 degrees colder this time of year than Columbus OH. I think we hit 47F on Jan 26th but we have had lots of single digits (F) this winter.
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It's NOT cold today
but it might be tomorrow. That's our winter this year. Two days ago it was 16F (-9C) in the morning and my son was complaining about having to walk to school. By afternoon it was in the 60s.
Today it may reach the 70s, which feels all the warmer when you've acclimated to colder temperatures. But tomorrow will be in the 30s (0C) and snow on the way. Sadly, though we tapped out our maple trees weeks ago, we still only have just over 5 gallons of sap. Not enough to start boiling and it might spoil. We need freezing nights and days in the high 30s to low 40s for good sap flow.
Sheesh, what a winter!
but it might be tomorrow. That's our winter this year. Two days ago it was 16F (-9C) in the morning and my son was complaining about having to walk to school. By afternoon it was in the 60s.
Today it may reach the 70s, which feels all the warmer when you've acclimated to colder temperatures. But tomorrow will be in the 30s (0C) and snow on the way. Sadly, though we tapped out our maple trees weeks ago, we still only have just over 5 gallons of sap. Not enough to start boiling and it might spoil. We need freezing nights and days in the high 30s to low 40s for good sap flow.
Sheesh, what a winter!
I had to turn mine on for about 20 minutes when I made the mistake of driving past the high school at exit time. There is road construction about 2 miles down the road with lane closure resulting in about a 20 minute backup. There was no wind, and open windows just brought heat and exhaust fumes.
I had the house open for about 10 hours yesterday. I try to exchange the stale air for fresh whenever possible.
We had the cold / warm day last week (Friday maybe). Yesterday it hit 81F, tonight mid 30's, but rain not snow. The flooding from the rain / snow / ice of last week along with the late week melt hasn't drained off yet, so more rain isn't welcome. Radar shows a line of storms stretching from the great lakes to the gulf. It will be here in about 2 hours. Cold will return tomorrow.
The $622 electric bill (also a midmonth billing cycle) managed to capture all of those 17 seriously cold days For several of those days it remained in the single to low teen digits, with a few mornings below zero. These were not normal for this area, as was yesterday's micro summer. The current electric bill arrived yesterday. It was $328 which is normal for this time of year. My wife has the TV on constantly, it and older cheap 65 inch, so it probably burns a few hundred watts. I'm constantly closing doors and turning off lights (all LED), so there is some waste energy.
It is a new house built just over 3 years ago with plenty of insulation surrounding the living areas. The basement is bare concrete block, which is a giant heat sink. Since my lab and computers are here, I spend considerable time here. I vent enough heat in the basement to keep one corner in the mid to high 50's. Basement insulation is on the to-do list. The other culprit is the builder supplied "meets minimum standards" heat pump.
Ours is imported from Canada.
I thought my bill was bad at $240.
I think the cold is supposed to stay well north of me. low for the next week is 40F, two weeks out 32F.
The power board loves minimum size heat pumps. During the summer when we have peak demand, the units can't keep up with the heat so the in house temp goes up and the units can't catch up until 9pm. It spreads the load over a longer period of time.
I think the cold is supposed to stay well north of me. low for the next week is 40F, two weeks out 32F.
The power board loves minimum size heat pumps. During the summer when we have peak demand, the units can't keep up with the heat so the in house temp goes up and the units can't catch up until 9pm. It spreads the load over a longer period of time.
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Very mild here. -6 to -9 the last few days.
Was out on the roof and took down the stuff I did not have time for last time. Very difficult do get around the house now, it's piling up.
In other news: found dog poop inside the snow cave! Do not understand what makes people think it's ok to have dogs running loose into other peoples back yards and do their business.
Was out on the roof and took down the stuff I did not have time for last time. Very difficult do get around the house now, it's piling up.
In other news: found dog poop inside the snow cave! Do not understand what makes people think it's ok to have dogs running loose into other peoples back yards and do their business.
