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Re: Question for the snow gurus

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By constructing log railings, aren't you creating a reservoir of snow whose weight should be added to the original design requirement?  If your railing is only one log high, say 12" diameter, then the additional weight might be about 18 psf, maybe tapering to zero at 10' from the log.  That's an increase of about 12% near the eave, not too bad.  But then, it seems to me all you've accomplished is a delay of the inevitable avalanche; once the reservoir is filled, you're back to square one as far as the sliding snow is concerned.
 
On the other hand, I have no idea how snow actually behaves.  I am not the snow guru you're looking for.  I've got more questions than answers . . . as in all my endeavors.
 
__________________
John P. Riley, PE, SE
Riley Engineering
----- Original Message -----
Sent: Wednesday, June 27, 2001 3:07 PM
Subject: Question for the snow gurus

I've designed a ski lodge where the snow load is 150 psf on a
5/12 pitch roof.  The owner has asked about putting log railings
on the roof to help keep the snow on the roof, and not on the ground
in front of the windows and doors.  I am trying to determine what force
to design the connection to the roof system.  UBC Appendix 1648
gives a force to design for vertical obstructions.  However, this seems
very excessive, especially when compared to what I've observed on
other roof systems.  Anyone know of any other guidelines to follow,
or procedure?
 
Thanks,
Dan Goodrich, P.E.
Utah