For some people, there has been some confusion in the "Snow Load" worksheet, distinguishing between the use of the maximum drift height, "hd(max)" and the design drift height, "hd". I have added a variable named "hd(max)" to distinguish between "hd(max)" and "hd" for determining the proper usage of each one in eventually calculating the drift width, "w" and the weight of the drift at the high end, "pd".

Below is the logic that I have used for the revised worksheet from the second paragraph of ASCE 7-05 Section 7.7.1.
I don't know about the rest of you, but to me that paragraph typifies some of the confusing and convoluted verbiage that is often found in building codes.

hd(max) = maximum of (hdL or hdw)
If hd(max) <= hc then w = 4*hd(max) and hd = hd(max) (where hc = clear height)
If hd(max) > hc then w = 4*hd(max)^2/hc and hd = hc

The current version is now 1.5.

It was brought to my attention in the "ASCE705S.xls" workbook in the "Snow Load" worksheet that was a wrong cell reference pertaining to the calculation for the snow drift sketch off to the right of the main calculation page. Here the user could input a distance from the end where the drift is a maximum value, and determine what the value of the drift is at that distance away. The calculation in Cell AC41 was using the actual calculated drift length, "w", when it should have been using the "w(use)" value of the drift, which is the minimum of either "w" or "w(max)". The error would show up only when the value of "w(use)" was controlled by the value of "w(max)".

I have made the appropriate cell reference correction, and the version of this workbook is now 1.6.

It was brought to my attention in the "ASCE705S.xls" spreadsheet workbook, for the rather rare case when the actual length of lower roof is less than the calculated snow drift length, the spreadsheet was reducing the magnitude of the snow drift to a value of zero at the edge of the roof. This was incorrect. Per ASCE 7-05 Section 7.7.1, when length of lower roof is less than calculated length of snow drift, the snow drift shall be truncated at the far edge of roof, and not reduced to zero there.

Thus, for this special case I had to create another result, in the form of the weight of the snow drift at the low end (minimum value). Please note that for this rather rare case, the illustration shown at the bottom of the calculation sheet will not actually depict the snow drift value at the low end (edge of building) correctly. Sorry, there's really not an easy nor convenient way to address that particular case, and to me it's not worth the effort trying to address it. The user will just have to be aware of it.

This workbook is now version 1.7.