print this page
AAA

Architecture

Loading

Flashings and Copings:
Changes in Roof Slopes

Description: Flashing a change in roof slope usually involves copper sheets 8 or 10 feet in length. They lap over the lower roof and are lapped by the upper roof. A cant of some kind is used to raise the roofing material and keep it from direct contact with the copper surface, to minimize line corrosion.

There are many combinations of roofing materials and corresponding numbers of appropriate details for each condition. The details shown are valid for shingle, tile, and slate roofing. The conditions are representative of typical installations.

The recommended minimum thickness of copper is 16 oz. unless slate or tile roofing is used. In this case 20 oz. plain or lead coated copper is used.

copper detail

A. Change of Roof Slope — Wood Cant This detail shows a shallower pitched roof joining a steeper pitched roof below. The copper flashing extends under the upper roofing at least 6". It laps the lower roofing a minimum of 4". The ends of each sheet should lap over the preceding one at least 4". The lower edge of the flashing is hemmed for stiffness.

The cant strip shown is wood fastened by copper straps, spaced 2'-0" apart, soldered to the copper flashing. A copper cant can be used instead, as shown in Detail B.

copper detail

B. Change of Roof Slope — Copper Cant In this detail the steeper pitched roof is above the one of lower pitch. The flashing method is similar to the one shown in Detail A.

copper detail

C. Flat to Sloped Roof with Gravel Stop This detail shows a flat built-up roof joining a lower pitched roof. Here the flashing extends a maximum 4" under the built-up roofing. It also has a built-in, formed gravel stop.

The lower edge of the flashing is hemmed and cleated to the sheathing at 12" O.C. As an alternate, a lock clip can be used as shown in Detail D.

48.gif

D. Change of Roof Slope — Alternate Wood Cant This detail shows an alternate cant. The wood cant is nailed to the sheathing. It is then covered by the copper flashing. The lower edge of the flashing is hemmed and held by a lock clip. Alternately, cleats at 12" O.C. can be used as shown in Detail C.

For Additional Information:

Design Handbook

Available in 2 formats:

Web Version
and
Desktop Application

Download AutoCAD Files

AutoCAD Detail Files
[ZIP - 4.5MB] is a complete set of CAD files for the designs shown in Architectural Details.

The AutoCAD files for individual details can be downloaded from individual topic pages by clicking the CAD File button next to an individual detail.

Order Design Handbook

Available in CDA's Publications
(publication #A4050).