Roof Gutter and Downspout

[macan1]

I would like to get some references about how to calculate size of Roof Gutter and Downspout (roof drain pipe).
It is for Canadian building code, using 15 min rainfall in mm.
Thanks.

 

[berkshire]

South of the border you could use SMACNA publication
Architectural Sheet Metal Manual
A best seller! Contains the most comprehensive set of recommended practices available for proper design and installation of custom-fabricated architectural sheet metal including roof drainage system design for scuppers, gutters and downspouts. Features new historical restoration section on skylights, cornices and spires; new moisture and maintenance guide; new mechanical fasteners and soldering chapter; and enhanced metals selection data. Offers new construction techniques and alternative methods of design and installation reflecting climatic conditions and rainfall rates. An upfront, fast “look-up” key speeds information retrieval. Also covers flashing, metal roofs, copings, gravel-stop fascia. Includes wind uplift pressure test reports confirming superior performance of custom-fabricated metal roofing. Applies to commercial, industrial and residential buildings

Surely there must be something like that north of the border.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[PEDARRIN2]

Two sources I have found for drainage sizing of gutters, albeit they are from the US.

Maryland Roof Gutter Design Method,

http://www.md.nrcs.usda.gov/technical/eng/desquide.html

Designing Roof Gutters for Barns,

http://www.lsuagcenter.com/NR/rdonl...ub3140designingroofguttersforbarnsHIGHRES.pdf

Both give good information and sound engineering.

There is also Table 1106.6 in the International Plumbing Code which may/not be applicable.

 

[racookpe1978]

I'd worry more about the winter snow and edge-ice buildup in Canada on the gutter rather than the mid-summer rain run-off. Seriously, "standard" gutters and downspouts will work under "standard" conditions, right?

Unless you're worried about a warehouse/stadium-sized roof area and its specialized gutter requirements. In which case, you need to start with area of each section and the max expected rain-per-hour rate for that specific location - which will vary over local conditions, not one number valid for one "national" rainfall good from British Columbia through the tundra and wheat fields over to Nova Scotia.

 

[racookpe1978]

Which - re-reading the question - would be that 15 mm rainfall.