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Have Trowel, Do travel
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this is what i learned:
First we must differentiate between fresh snow, old snow and compact (wet and watery) . The first has a weight ranging between 80 and 200 kg / cu m (cubic meter), the second between 200 and 500 kg / cu m, while the third can be up to 800 kg / cu m. The ice on the other hand is around 900 kg / cu m.


That said, how much they weigh, for example, 20 inches of new snow over an area of ​​one square meter? The calculation is simple: height in meters x specific gravity.
In our case, such as taking specific weight 100 kg / cubic meter, there will be 0.2 meters x 100 lbs = 20 kg (per square meter).
If we wanted to estimate the weight of 60 inches of old snow and wet, should be done for 0.6 meters 400 kg = 240 kg (always per sqm). Almost like having 3 adult men for every square meter. With this load, you're sure that your roof will remain firmly?
 

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Discussion Starter · #5 · (Edited)
Bug Fix

Fixed a small bug in the html formatting this morning. Try it now, tell me if you have any problems.

The intent of the snow load calculator is to give you the appropriate balanced and unbalanced snow load as per the ASCE 7-10. What is required is the ground snow load and some general information about your roof. It all pretty much follows a very simple algorithm set out in chapter 7 "Snow Loads".
 

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Discussion Starter · #10 ·
Ground Snow Loads

I've recently spent some time on looking at the snow load requirements of the ASCE 7-10 and the various state modifications to the IBC and IRC. Obviously this is a gargantuan task, to summarize all this data and present it in a usable fashion. I have managed to chip away at a few states that have standardized snow load data or equations. The latest state I've tabulated is New York State:

http://design.medeek.com/resources/snow/newyorkgroundsnowloads.html

My map of the ASCE 7-10 ground snow loads is still unfinished, not because I cannot finish it but because I am currently waiting on a response back from the ASCE licensing division about the reproduction of the data presented in Fig. 7-1 (ground snow load map). Reproducing or displaying a scanned version of the map seems to be less of a concern that creating an accurate electronic version of the map that is much more useful to the general public and engineering community.

I am summarizing each States snow load requirements on this page:

http://design.medeek.com/resources/snow/statesnowloads.html

As you can see I've only just started. Some states such as Colorado let the local jurisdictions (City and County) set their own snow load requirements so creating a map for the entire state is more difficult but not necessarily impossible. Some states such as Oregon have developed much more sophisticated online systems, I applaud their efforts.
 

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Discussion Starter · #11 ·
Oregon Snow Load map is up. This one, like the Montana Map, connects to the snow load database hosted by the SEAO. It also compares the retrieved value against the 20 psf snow load minimum as well as checks the modeled elevation against the actual site elevation and flags the user based on these checks.

The advantage to using this tool is that you don't need to know the lat. and long. off hand, just click on the map and it does the rest.

http://design.medeek.com/resources/s...snowloads.html

Also added in tile roof surface to the calculator by request from a California native.
 

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Discussion Starter · #12 ·
Just completed the Ground Snow Load Map tonight.

http://design.medeek.com/resources/snow/groundsnowloads.html

Digitizing it, so that it was accurate, took far longer than I had planned on but once I was underway I wasn't about to stop.

Note how most of the western US requires case studies, hence many of these states have their own snow load maps and research to back them up.
 

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Discussion Starter · #13 ·
Interestingly I had a company that manufacturers and installs solar panels contact me regarding the ASCE ground snow load map. They were wondering if there was a way so that their website could send an http request to the map with a latitude and longitude and have it kick back the snow load. Since the map is already in digital format you would not think this would be hard to do. So I got thinking about how I could build a program that given a certain lat and long would automatically click on the map and then fire back the elevation, snow load, etc...

The only problem is google maps implementation of the KML layer does not allow this transmittal of information. So I basically banged my head against the wall for almost 2 weeks trying to do the impossible. However, I was not ready to throw in the towel just yet. Since the KML data is just plain text, (coordinates) I thought there must be some way to analyze this data and determine if a given location is within a certain polygon and if it is then be able to assign that polygon description (ASCE snow load details) to a variable which is then delivered to the client. Turns out this is called the point in the polygon problem and it is well documented:

http://en.wikipedia.org/wiki/Point_in_polygon

So I was about to write an algorithm for ray casting which would have taken some time. Then I thought maybe someone else has done this before and sure enough I found a couple of good perl modules that handled this nicely and I narrowly avoided reinventing the wheel. Just a few lines of Perl later and I had managed to create a nice little API for the ASCE ground snow load data:

http://design.medeek.com/resources/medeekapi.html
 

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Educator of Codes
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Finally finished up the snow load calculator. Moved it to this page:

http://design.medeek.com/resources/snow/snow_calculator.pl

Give it a whirl and let me know what you think.

I wish there was an easy way to calculate the ground snow loads for a given location but unfortunately there is not.
Excellent job on this. Myself and a few other plan reviewers will put this through the paces to see if we can find any quirks in it. Very useful indeed.
Thank you!
 
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