Architectural Flashing Supply
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Gutters, scuppers and conductor heads · Lesson 3 of 4

Gutters, scuppers and conductor heads: methods and worked application

The method in order, CDA's Chicago example worked through, a conductor head and its downspout laid out, the AFS box gutters read leg by leg, and the pieces and laps for a run.

You will be able to: Follow a documented method from flow to a shop-ready gutter or conductor head: check the arithmetic on a drawing, lay out a head, read a FlashDraft box gutter, count pieces and laps, and record assumptions, units and inspection points.

16 min · 12 slides · 14 questions

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Slide 1 of 12

From rainfall to the shop

The order of work: rainfall for the site, the area draining to each outlet, the flow, the downspout and gutter sizes, then the FlashDraft profile, the AFS limits check, forming and inspection.

The first steps belong to the designer. The shop checks that the drawing it receives adds up and can be made.

From rainfall to a shipped gutterEight numbered steps in two groups. The designer: rainfall for the site, area to each outlet, flow, and downspout and gutter sizes. The shop: FlashDraft profile, AFS limits check, forming on the folder, and inspect, record and ship. A note says overflow drainage is sized by the designer to the adopted code.The designerThe shop12345678Rainfall: NOAA Atlas 14Area x CDA pitch factorFlow Q = 0.0103896 x A x IDownspout and gutter sizesFlashDraft profile, as approvedAFS limits: girth, length, bendsForm on the Thalmann folderInspect, record and shipOverflow drainage is sized bythe designer, to the adopted code

A flow of eight numbered steps from the rainfall for the site to inspection and shipping, split into the designer's steps and the shop's steps, with a side note that overflow drainage is sized by the designer to the adopted code.

1
Rainfall for the site (NOAA Atlas 14)
2
Area to each outlet: plan area x CDA pitch factor
3
Flow: Q = 0.0103896 x A x I (Design Center)
4
Downspout and gutter sizes (CDA method, by the designer)
5
FlashDraft profile from the approved drawing
6
AFS limits: girth up to 48 in, piece up to 126 in, metal and bends
7
Formed on AFS's Thalmann folder
8
Inspect, record and ship
The designer's steps come first; the shop checks the drawing adds up and can be made. AFS forms on its Thalmann folder.

Sources

Glossary

Pitch factor
The CDA multiplier on plan area for a pitched roof, from 1.00 to 1.30.
M ratio
In the CDA method, a gutter's depth divided by its width, assumed and then checked.
Girth
The flat width of the blank, the legs added at the mold line.
Mold line
The theoretical sharp corner where two outside faces meet; AFS legs are measured to it.
Lap
The length by which one gutter section overlaps the next, laid in the direction of flow.