snow load on roofs

[Francesca Knowles]

Originally Posted by Carol H

Your correct when the snow has melted down 9" as you suggest above but my comment was in response to your general comment below that although snow does in crease in density its "total load" doesn't increase, which isn't correct.

Yes, it is.
Density is a unit of measure and load is a unit of weight- if speaking of "totals", neither has any effect on the other.

[cpaharley2008]

You say potato, I say potataà, let's call the whole thing off.

[Spanke]

Spanke

[Carol H]

Originally Posted by Spanke

Attachment 68214

Spanke

[Paul O.]

...is the reason I was working my tail off last December to finish my Scamp shed. This picture was taken two days later, on 12/15/2013 (Central Vermont). It sure is very nice not to have to worry about pulling the snow from the Scamp after every storm.
And, to put it simply, a thousand pounds of snow is still going to be a thousand pounds, unless it melts, or more stuff falls. When we get a March rain after three feet of snow, that is when I head for the roof with a shovel.

[jgraps1958]

I think it's time to clear off the trailer !!!!!!!!!!! Tomorrow !!

[Francesca Knowles]

Originally Posted by jgraps1958

I think it's time to clear off the trailer !!!!!!!!!!! Tomorrow !!

If "tomorrow" doesn't get here quite in time, you may find this interesting reading:

http://www.fiberglassrv.com/forums/f...oof-47443.html

[D Davis]

I cleaned the snow off of my camper today three times...didn't want to know how much snow would it take to harm it. Just knew I had to do it. Got just shy of 2 feet of snow.

[rabbit]

You certainly can't increase the total weight of a given volume of snow by melting it. Carol may have and Francesca may have but God bless the child who knows this ain't so (you know who you are). Of course the residue of a month or two of snowfalls and freezing rain may present as a depth on the roof not much greater and in some cases less than the first powpow of the season.

jack

[Francesca Knowles]

Originally Posted by rabbit

You certainly can't increase the total weight of a given volume of snow by melting it. Carol may have and Francesca may have but God bless the child who knows this ain't so (you know who you are).

jack

Say what??????

Please take a moment to review my posts on the subject, quoted below...no skimming this time, please...


First I said:

Originally Posted by Francesca Knowles

The only way for snow to get "heavier" as it melts is for more snow or rain to fall on it, thus adding more water.

There may be an added danger to roofs as snow melts if it causes pooling somewhere on the roof, though.

Next, my response to Carol's assertion below:

Originally Posted by Carol H

.. snip... my comment was in response to your general comment...that although snow does increase in density its "total load" doesn't increase, which isn't correct.

Originally Posted by Francesca Knowles

Yes, it is.
Density is a unit of measure and load is a unit of weight- if speaking of "totals", neither has any effect on the other.

...Well?

[rabbit]

I'll make this easy. You win. "Load" is not a unit of weight so maybe it's offsetting penalties. Who cares?

jack

[Carol H]

Originally Posted by rabbit

You certainly can't increase the total weight of a given volume of snow by melting it. Carol may have

jack

With all due respect Jack I am going to suggest that you re read my post 10 which was the point I was attempting to make - the snows water content can increase and the weight goes up - doesn't need to melt or an increase in snow volume to happen.

[cpaharley2008]

anyone got any popcorn?……...

[Raz]

F=mA

If 12" of snow compacts to 8", no melting, no evaporation, despite the change in density there is no change in mass. Unless the acceleration due to gravity changes , the force (weight) is constant. If you could weigh the snow then melt it and weigh the water, you'll get the same value. Raz

[Spanke]

Originally Posted by Carol H

With all due respect Jack I am going to suggest that you re read my post 10 which was the point I was attempting to make - the snows water content can increase and the weight goes up - doesn't need to melt or an increase in snow volume to happen.

NO! NO! NO! NO!



Spanke

[Carol H]

LOL I give up!

[jgraps1958]

WOW !!!!! That Reagan pic is great !! I will remove the snow as soon as I can get to it. If it caves in that will be a tragedy but I do have insurance, paid a year in advance.

[Nate R]

Originally Posted by Carol H

With all due respect Jack I am going to suggest that you re read my post 10 which was the point I was attempting to make - the snows water content can increase and the weight goes up - doesn't need to melt or an increase in snow volume to happen.

I went and read it. The DENSITY goes up. THere is NO new weight. You conveniently omitted the portion that talks about WHY the density changes.

From your link:

Once the snow is on the ground, it will settle under its own weight (largely due to differential evaporation) until its density is approximately 30% of water. Increases in density above this initial compression occur primarily by melting and refreezing, caused by temperatures above freezing or by direct solar radiation. In colder climates, snow lies on the ground all winter. By late spring, snow densities typically reach a maximum of 50% of water.[39

So, again, the total weight does NOT go up, just the density increases

[Carol H]

LOL - clearly I haven't done well at making what was my original intent of commenting on the topic of snow loads on roofs of fiberglass trailers.

My last attempt - promise! The weight and density of any square foot of snow is not consistent in weight! Its weight, density & ultimately the total load on the roof of a trailer depends on the % of water content of the snow, wether that be at the time it falls or through other environmental factors resulting in it compacting down. The weight and density of a foot of high water content snow on a square foot area of a roof will have a higher density & can and will outweigh a foot and a half of the light fluffy lower water content snow on the same square foot of roof.


Bottom line being no one can say oh there is only a foot of snow on my trailer and it was fine with that last year and believe it will be the same this year as the weight of a foot of snow and thus the total load on the roof can vary greatly. Simple as that.

[David Tilston]

Yup, this has been entertaining. Who's on first?