Program Description:

"ASCE710S" is a spreadsheet program written in MS-Excel for the purpose of flat roof snow loading analysis for buildings and structures per the ASCE 7-10 Code.  Specifically, coefficients and related and required parameters are selected or calculated in order to compute the net design snow loads, including snow drift due on lower roofs and rain-on-snow surcharge.

This program is a workbook consisting of three (3) worksheets, described as follows:

Worksheet Name - Description
Doc - This documentation sheet
Snow Load - Snow loading analysis for buildings with flat or low slope roofs
Snow Map - Ground snow loads map (Figure 7-1 of ASCE 7-10 Code)

Program Assumptions and Limitations:

1.  This program specifically follows Section 7.0, Snow Loads, of the ASCE 7-10 Standard, "Minimum Design Loads for Buildings and Other Structures".  
2.  This program assumes only snow loading analysis for buildings with a flat roof, or low slope roof <= 5 degrees. (Note: for reference, a 1:12 roof slope equates to 4.76 degrees, and the program allows a slope up to 1.05:12.)
3.  This program addresses only balanced snow loading, snow drifts on lower roofs, and rain-on-snow surcharge loading.  Unbalanced roof snow loads are not considered.
4.  This program assumes the possibility of either leeward or windward snow drifts, and the larger of the two calculated drift heights per the code is used as the design drift height.  Leeward drift results from snow blown off a high roof onto a lower roof.  Windward drift results from snow blown against a projection or wall below a high roof.
5.  This program determines any rain-on-snow surcharge loading when applicable.  Rain-on-snow surcharge loading of 5 psf is not required for ground snow loads, pg > 20 psf, nor for roof slopes (in degrees) >= W/50, where "W" is equal to the horizontal distance (in feet) from the eave to the ridge on the building. This program conservatively combines the rain-on-snow surcharge loading with snow drift loading.  However, per Code, rain-on-snow surcharge loading need not be combined (superimposed) with snow drift loading.
6.  This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc.  (Note:  presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell.  Merely move the mouse pointer to the desired cell to view the contents of that particular "comment box".)

Calculation Reference
ASCE 7-10
Structural Design
Snow Loads

Calculation Preview

20 Jan 2015
Last Modified
20 Jan 2015
File Size:
623.50 Kb
File Version:
File Author:
Alex Tomanovich

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Comments: 2
Heinzig 5 years ago
Excellent software; thanks. MPH
ATomanovich 9 years ago
It was brought to my attention that there had been a change made in Section 7.3.4 of the ASCE 7-10 Code for the use of the minimum flat roof snow load, that I had missed.
The minimum flat roof snow load is now separately defined as "pm", and the Code now states that the minimum flat roof snow load need not be used in combination with snow drift. The worksheet had been using the maximum of either the calculated flat roof snow load, "pf" or the Code prescribed minimum value, and adding that to the snow drift, which then was potentially conservative.
I have made this correction, and I have also added a visual comment to the upper right of the sketch in the worksheet to emphasize that point..
The current version of this workbook is now 1.1.