How to calculate snowload?

[Bishopknight]

Hey everyone 

I am trying to figure out how to calculate snowload from annual snowfall in inches. Can anyone show me how?

Taking Harmony, Maine as an example ( with data collected from the National Weather Service ) is there a way to calculate what the PSF would be?

Monthly Totals/Averages
Snowfall (inches)
Years: 1978-2001

             Jul   Aug   Sep   Oct   Nov   Dec   Jan   Feb   Mar   Apr   May   Jun  Season
Avg      0.0   0.0    0.0    0.4   4.0    13.1  17.4  13.6  12.2   3.2   0.0   0.0    63.9

[glenn kangiser]

It's done for you by the local building officials - usually it's based on a certain elevation in the area you live in and can vary by local conditions.

Here is 30 lbs, but we haven't had over a foot of snow in years.  Wet snow weighs a lot more than dry also - so you just have to ask how much snow the government will allow to fall.

[CREATIVE1]

And sometimes the snow load you have to build for is a little ridiculous, but if you want to build, you've got to satisfy those code people.  Since I'm at 1,200 feet above sea level in Washington, I have to build to 55 pound snow load (above 1,000 feet).  I have been talking to the locals, and they think I'll get snow where I am maybe twice a year.  Plus most of my roof is 12/12 pitch.  But it turns my ridge beams into unwieldy monsters.

[Willy]

All depends on where your located. I have to have a min 70 lb rating on my new cabin I am building and if I remember right it was 125 lb on my home I live in now. Both places are above the 2700 ft level. Mark

[MountainDon]

I'd say when it come to planning a new structure there are two things that are mostly governed by local conditions.

Foundation depths.
Snow loads

Everything in between is more or less the same across the country.

My 0.02

[davidj]

At higher altitudes the snow load can get very local too - even knowing what the house down the road at the same elevation is built to doesn't necessarily mean that your house will be the same.  Our local town of Johnsville is about 3 blocks by 5 blocks but has a range of snow loads.

At 5000ft in the Northern Sierras they tried to persuade us to build to 150psf, but our area was not fully surveyed and legally it was 85psf.  We went for 120psf in the end, which means a 6x18 beam to support a 20' x 20' area of roof.  There is 4' of very wet snow on the ground right now, so I guess there's some justification.

Thinking about it, with a 6x18 I'm gonna be getting into the chainsaw-and-bulldozer end of framing.  I guess I'd better start rereading more of Glenn's old posts...

[glenn kangiser]

Don't forget the sledge hammer.

[CREATIVE1]

At higher altitudes the snow load can get very local too - even knowing what the house down the road at the same elevation is built to doesn't necessarily mean that your house will be the same.  Our local town of Johnsville is about 3 blocks by 5 blocks but has a range of snow loads.

At 5000ft in the Northern Sierras they tried to persuade us to build to 150psf, but our area was not fully surveyed and legally it was 85psf.  We went for 120psf in the end, which means a 6x18 beam to support a 20' x 20' area of roof.  There is 4' of very wet snow on the ground right now, so I guess there's some justification.

Thinking about it, with a 6x18 I'm gonna be getting into the chainsaw-and-bulldozer end of framing.  I guess I'd better start rereading more of Glenn's old posts...

6 x 18--I wish!!  They want a 6 x 24 for my house, 30 x 16.

[glenn kangiser]

Had to look up Johnsville, davidj.  You are a ways above Drew.

Do you guys still drive Dodges up there?



http://www.johnsville.net/

[davidj]

Don't forget the sledge hammer.

So much to learn!  (And so few bandages to sort out the incidental trauma).

Fortunately I went through the "be careful of things falling off the roof and onto your head" learning experience last Summer as I'm guessing a 750lb beam would raise quite a bump if dropped from 20ft up.

[davidj]

Had to look up Johnsville, davidj.  You are a ways above Drew.

I think if you pop over the Pacific Crest from our place, then head downhill for 50 or so miles (as the crow flies) you'll end up at Drew's.  If you climb up the local peak on a clear day, you can just about see his trenches, much as you see roman roads from the tops of hills in Europe...

Do you guys still drive Dodges up there?

http://www.johnsville.net/

I'm guessing my neighbor probably still has that car on his lot (he's got most other pieces of machinery that made it to Plumas County in the last 100 years!)

Johnsville is a great place.  According to the census, population 21, median male income $0 and, rumor has it, more millionaires per head than any other town in California.  It's a historic preservation district and seriously expensive (for the middle of nowhere), but if you head two miles down "red dirt road" you can find lots for $20K/acre and displaced computer programmers yielding chainsaws, sledge hammers and very large bits of wood.

[NM_Shooter]

Take a look here:  http://www.alpineequip.com/upload/391/FELDMANNpg24252627.pdf

[MountainDon]

So you think you have snowload problems?













Watertown, NY area.
thanks to John (redoverfarm)

[intelijoc]

I called the building department- easy.  Mine is 125lb elevation is 11,600ft


intelijoc

[John_C]

Here is a pdf download where you can look up wind & snow load by county.  If the link doesn't work post a reply & I'll try to find the bug in it.  It's a large file... since it's for every county in the U.S.

www.chiefbuildings.com/design/MBMA2002.pdf

[Redoverfarm]

Hey John do you have the original site?  This one is Virginia.

[John_C]

Oops, my bad.  I changed the link above.  I downloaded the file months ago & renamed it, I had to search for it again and posted the wrong link. 

[MountainDon]

That's a handy reference. I'm going to place it in a new topic under Referral Links.

Note that many locations in the west are site specific. The terrain in the mountains can cause grossly different loads in areas less than a mile apart, different sides of a peak/ridge.

[phalynx]

Don, those are some of the funniest snow pics I have seen..  I love snow, but I would imagine that would be a little "overwhelming"

[Ernest T. Bass]

Yeah, that's pretty amazing.. Though, last year there were some drifts that measured about 15 ft. deep just a little ways inland from us.. 

[glenn kangiser]

Sorry but that snow is not compatible with life...