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Re: 25% snow load is Conservative

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If anyone is interested in snow pack, amounts densities in the Sierra Nevada
mountains check out this web site (below).  The site contains over sixty
years of historical snow pack data.  You may have to do some surfing to find
out which survey course is near where you want.  For example, course 108
gets you echo summit near Lake Tahoe EL+AD0-7450', +ACM- 103 is near Emerald bay (+AEA-
Tahoe) EL 6600'.  The data tends to show that densities can approach 33pcf,
but they occur in April when the snow pack is less than maximum, (by the way
check out 1969 and 1983 for record snow pack years).  In my somewhat limited
testing I have found that roof SL densities cannot exceed 22pcf for a sloped
(drained) roof.

I also have found that the roof snow loads prescribed by most of our local
building departments are extremely conservative.  Combining this
conservative snow load with a conservative +ACU- of SL with seismic DL's tends
to produce overkill in terms of lateral designs.

http://monsoon.water.ca.gov/cgi-bin/snowQuery


Randy Vogelgesang S.E.
South Lake Tahoe, CA

-----Original Message-----
From: Bill Sherman +ADw-SHERMANWC+AEA-cdm.com+AD4-
To: seaoc+AEA-seaoc.org +ADw-seaoc+AEA-seaoc.org+AD4-
Date: Friday, April 17, 1998 6:58 AM
Subject: Re: 25+ACU- snow load is Conservative


+AD4-Brian Veit wrote:
+AD4-
+AD4APg- Some counties have chosen to go big, such as Placer Co +AEA- 1/3rd and Amador
+AD4-Co
+AD4-(kirkwood) +AEA- 1/2+ACE-  In addition, the snow loads in these areas are routinely
+AD4-above 300 psf. +ADw-
+AD4-
+AD4-At a maximum density of 35 pcf (per UBC Appendix Chapter 16), 300 psf would
+AD4-equate to 8 1/2 feet of snow.  Here in Colorado, I have a copy of a county
+AD4-requirement for mountain snow loads which lists snow loads by elevation and
+AD4-only goes up to 150 psf maximum at 11,000 feet.  (What do you make your
snow
+AD4-out of in California? :) )
+AD4-
+AD4-
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