Stupid Question ... but I'zze Gotsta ask anyway

rgilfert · 02-09-2015, 07:59 AM

Having read MAXUM's forum thread last week titled "Think about clearing snow off your roof" I got a little scared and as result spent virtually the entire weekend clearing the 24" of snow off of our roof here in Bedford (unfortunately I can't get out to Rattlesnake to do the same thing there). As I was repetitively moving the snow to the roof's edge I was amazed at the shear weight that a 24" column of snow has!! As of this morning, literally tons of weight have been removed and I feel much better prepared for the additional 12" that is falling as I speak (thanks, Maxum)!

OK, so I was lying in bed early this morning thinking about what a good doobie I had been for clearing my roof and one thought lead to another and suddenly I found myself thinking about the frozen lake, the size of the Broads and the weight of the fallen snow and the following question came to mind: over the enormous expanse of the Broads why doesn't the weight of the ice plus the weight of the snow cause the ice to cave in?? I know that this sounds stupid (and I'm sure that it is) .... but I'm being serious....it seems, to me, that it would.

secondcurve · 02-09-2015, 08:07 AM

The snow is spread out very widely on the ice so everything is in balance. Two feet of snow and two feet of ice. No big deal. Your roof works the same way. Ask yourself how many roof collapses have you seen over the years? I know I have never seen one. As someone noted in an earlier thread there are many times more people getting injured from falling off roofs then from roofs falling on folks.

TiltonBB · 02-09-2015, 08:09 AM

Who don't the ice cubes in your evening cocktail sink?

The ice has more air entrained and is less dense than the water it sits on. Because it is lighter it will stay on top.

That is my unscientific explaination. Others, with more education on these matters, may have a better way to answer your question. They might even tell me that I am wrong!

upthesaukee · 02-09-2015, 08:13 AM

Your house is just a frame surrounding airspace. Snow loads are computed to give guidance as to how much weight a roof and supporting structure can support. When the weight of snow and ice exceed a structure's weight bearing capability, the result is the collapse of the structure into the airspace.

The lake, on the other hand, has ice forming over a solid (water), and the added snow on the ice has nothing to fall into like the airspace of a house.

Perhaps, if the lake were to be drawn down to create space under the ice, you would see the ice and snow collapse down to new lake water surface.

Ok, back to my 603 Winni Ale, as I dream of being back on Winni in the boat.

upthesaukee · 02-09-2015, 08:21 AM

Quote:

Originally Posted by secondcurve

The snow is spread out very widely on the ice so everything is in balance. Two feet of snow and two feet of ice. No big deal. Your roof works the same way. Ask yourself how many roof collapses have you seen over the years? I know I have never seen one. As someone noted in an earlier thread there are many times more people getting injured from falling off roofs then from roofs falling on folks.

Probably fewer collapses from peaked roof structures than from flat roof structures, but certainly roofs collapse from the weight of snow and ice.

Here is an article about an apartment building in Nashua that had a roof collapse last week: http://www.newhampshire.com/article/.../0/AGGREGATION

Also, a Walmart closed recently until they cleared off the roof of ice and snow because they feared a collapse.

Also from the Concord Monitor last year regarding a pitched roof in Henniker: http://www.concordmonitor.com/news/1...dents-unharmed

Garages and carports are also likely victims. I don't think we hear about many of them, unless it involves a commercial building or an apartment house, or something really big like that.

Webbsatwinni · 02-09-2015, 08:46 AM

Rgilfert,

I was out on the island this past weekend and had the same concern, surprisingly there snow on the roof surfaces wasn't that bad. I am sure it will grow with the new snow but the base wasn't bad at all.

jetlag100 · 02-09-2015, 09:07 AM

You made me remember a time when my Dad had the guys he worked with (Raytheon) figure a thought he had about the lake....he would have had an answer for you, but, he's been long gone from this earth..wish I could tell you the story, but it would be considered disgusting, by some! LOL Ah, the memories

Misha888 · 02-09-2015, 09:12 AM

Quote:

Originally Posted by Webbsatwinni

Rgilfert,

I was out on the island this past weekend and had the same concern, surprisingly there snow on the roof surfaces wasn't that bad. I am sure it will grow with the new snow but the base wasn't bad at all.

We are again getting hosed in the snow department here in the lakes region.

TheProfessor · 02-09-2015, 09:37 AM

A lake neighbor.
He purchased a lot on other side of road - not on lake.
He had a 3 door garage built.
I viewed the construction of such.

After the pad - a tractor trailer came in - with all walls and such.
Garage went up in one day.

Apparently he saved money by purchasing a pre-built or factory built garage.

Lasted a good 10 years.

Then one snow storm - during the winter of snow storms - the garage completely collapsed.

He had the garage rebuilt to exact same. Except this time he had constructed a stick built garage. And that one is still standing.

The garage has never been heated.

Greene's Basin Girl · 02-09-2015, 11:31 AM

We got tired of shoveling our roof so we changed it to a metal roof. We do not have to shovel anymore, but when the temperature rises the snow falls and it piles up quickly on our deck below. We also have to be careful to not be anywhere under the roof if there is snow that is falling off the roof. Sometimes when the snow falls it sounds like an earthquake when it hits the deck. That being said though, we are glad that we put on a metal roof. I use to worry about my husband falling off the roof when he was up there. Now there aren't any worries.

jetlag100 · 02-09-2015, 12:00 PM

Quote:

Originally Posted by Greene's Basin Girl

We got tired of shoveling our roof so we changed it to a metal roof. We do not have to shovel anymore, but when the temperature rises the snow falls and it piles up quickly on our deck below. We also have to be careful to not be anywhere under the roof if there is snow that is falling off the roof. Sometimes when the snow falls it sounds like an earthquake when it hits the deck. That being said though, we are glad that we put on a metal roof. I use to worry about my husband falling off the roof when he was up there. Now there aren't any worries.

I also have a metal roof. I totally understand the "earthquake"! Company freaks out if they happen to be up when the snows slides...LOL Love not having to worry about anyone going up there to shovel, too!

MAXUM · 02-09-2015, 12:56 PM

I don't get up on my roof to clear it off, instead I have a roof rake with a 21' extension on it to clear it off. In fact it's not so much about getting every flake of snow off the roof, more or less to reduce the overall load especially if your roof is prone to having large drifts form which can pile up many feet deep, or build ice dams along the edges.

Metal roofing is the bomb. That is on my list of things to do in the coming years.

02-09-2015, 07:59 AM	#1
rgilfert Senior Member Join Date: Mar 2012 Location: Bedford, NH / Rattlesnake Island Posts: 299 Thanks: 152 Thanked 227 Times in 57 Posts	Stupid Question ... but I'zze Gotsta ask anyway Having read MAXUM's forum thread last week titled "Think about clearing snow off your roof" I got a little scared and as result spent virtually the entire weekend clearing the 24" of snow off of our roof here in Bedford (unfortunately I can't get out to Rattlesnake to do the same thing there). As I was repetitively moving the snow to the roof's edge I was amazed at the shear weight that a 24" column of snow has!! As of this morning, literally tons of weight have been removed and I feel much better prepared for the additional 12" that is falling as I speak (thanks, Maxum)! OK, so I was lying in bed early this morning thinking about what a good doobie I had been for clearing my roof and one thought lead to another and suddenly I found myself thinking about the frozen lake, the size of the Broads and the weight of the fallen snow and the following question came to mind: over the enormous expanse of the Broads why doesn't the weight of the ice plus the weight of the snow cause the ice to cave in?? I know that this sounds stupid (and I'm sure that it is) .... but I'm being serious....it seems, to me, that it would.

02-09-2015, 08:09 AM	#3
TiltonBB Senior Member Join Date: Feb 2005 Location: Gilford, NH and Florida Posts: 2,897 Thanks: 644 Thanked 2,153 Times in 900 Posts	Maybe Who don't the ice cubes in your evening cocktail sink? The ice has more air entrained and is less dense than the water it sits on. Because it is lighter it will stay on top. That is my unscientific explaination. Others, with more education on these matters, may have a better way to answer your question. They might even tell me that I am wrong!

02-09-2015, 08:13 AM	#4
upthesaukee Senior Member Join Date: Jan 2003 Location: Alton Bay Posts: 5,547 Blog Entries: 2 Thanks: 2,398 Thanked 1,918 Times in 1,061 Posts	your house is open space with tons of weight over it. Your house is just a frame surrounding airspace. Snow loads are computed to give guidance as to how much weight a roof and supporting structure can support. When the weight of snow and ice exceed a structure's weight bearing capability, the result is the collapse of the structure into the airspace. The lake, on the other hand, has ice forming over a solid (water), and the added snow on the ice has nothing to fall into like the airspace of a house. Perhaps, if the lake were to be drawn down to create space under the ice, you would see the ice and snow collapse down to new lake water surface. Ok, back to my 603 Winni Ale, as I dream of being back on Winni in the boat. __________________ I Live Here... I am always UPTHESAUKEE !!!! Last edited by upthesaukee; 02-09-2015 at 10:08 AM.

02-09-2015, 09:07 AM	#7
jetlag100 Senior Member Join Date: Apr 2008 Location: Revere, Massachusetts and Moultonborough, N.H. Posts: 311 Thanks: 228 Thanked 79 Times in 50 Posts	Weight of snow on ice You made me remember a time when my Dad had the guys he worked with (Raytheon) figure a thought he had about the lake....he would have had an answer for you, but, he's been long gone from this earth..wish I could tell you the story, but it would be considered disgusting, by some! LOL Ah, the memories

02-09-2015, 08:07 AM	#2
secondcurve Senior Member Join Date: Jan 2005 Posts: 2,084 Thanks: 1,267 Thanked 557 Times in 286 Posts	The snow is spread out very widely on the ice so everything is in balance. Two feet of snow and two feet of ice. No big deal. Your roof works the same way. Ask yourself how many roof collapses have you seen over the years? I know I have never seen one. As someone noted in an earlier thread there are many times more people getting injured from falling off roofs then from roofs falling on folks.

02-09-2015, 08:46 AM	#6
Webbsatwinni Senior Member Join Date: Sep 2007 Location: Lebanon Ct and Rattlesnake Island Since 2007 Posts: 610 Thanks: 180 Thanked 137 Times in 72 Posts	Rgilfert, I was out on the island this past weekend and had the same concern, surprisingly there snow on the roof surfaces wasn't that bad. I am sure it will grow with the new snow but the base wasn't bad at all.

02-09-2015, 09:37 AM	#9
TheProfessor Senior Member Join Date: Nov 2010 Posts: 1,062 Thanks: 17 Thanked 326 Times in 198 Posts	A lake neighbor. He purchased a lot on other side of road - not on lake. He had a 3 door garage built. I viewed the construction of such. After the pad - a tractor trailer came in - with all walls and such. Garage went up in one day. Apparently he saved money by purchasing a pre-built or factory built garage. Lasted a good 10 years. Then one snow storm - during the winter of snow storms - the garage completely collapsed. He had the garage rebuilt to exact same. Except this time he had constructed a stick built garage. And that one is still standing. The garage has never been heated.

02-09-2015, 11:31 AM	#10
Greene's Basin Girl Senior Member Join Date: Sep 2009 Location: Moultonborough, NH Posts: 1,515 Thanks: 394 Thanked 527 Times in 269 Posts	We got tired of shoveling our roof so we changed it to a metal roof. We do not have to shovel anymore, but when the temperature rises the snow falls and it piles up quickly on our deck below. We also have to be careful to not be anywhere under the roof if there is snow that is falling off the roof. Sometimes when the snow falls it sounds like an earthquake when it hits the deck. That being said though, we are glad that we put on a metal roof. I use to worry about my husband falling off the roof when he was up there. Now there aren't any worries.

02-09-2015, 12:56 PM	#12
MAXUM Senior Member Join Date: Apr 2004 Location: Kuna ID Posts: 2,755 Thanks: 246 Thanked 1,942 Times in 802 Posts	I don't get up on my roof to clear it off, instead I have a roof rake with a 21' extension on it to clear it off. In fact it's not so much about getting every flake of snow off the roof, more or less to reduce the overall load especially if your roof is prone to having large drifts form which can pile up many feet deep, or build ice dams along the edges. Metal roofing is the bomb. That is on my list of things to do in the coming years.