8.3. Batten Seam Roofing

Description: Batten seam roofing consists of copper pans running parallel to the roof slope, separated by wood battens. The battens are covered with copper caps that are loose locked into adjacent pans. The width of these preformed or field formed pans may vary. The recommended maximum depends on the weight of copper, see below.

The battens, which can have a wide variety of shapes and sizes, provide not only a means of securing the roofing, but also permit a wide variety of design expressions. Transverse seams are required to join the ends of preformed pans (see Detail 8.3D).

There are two methods of accommodating expansion movement of the pans. Both rely on a space of 1/16" between the upstanding leg of a pan and batten. Both use battens that are nominally 2" x 2". In the preferred method, the battens are tapered so their base is 1/16" narrower on each side than at the top. The upstanding leg of the pan is then formed vertically. The alternative method uses square battens. The pans are formed 1/16" narrower on each side, with their upstanding legs bent at an angle greater than 90 degrees to meet the batten cap.

Copper Weight Requirements for Batten Seam


  1. 16 oz. sheets for pans not exceeding 20" wide
  2. 20 oz. sheets for pans exceeding 24" wide

Batten caps are joined at their ends with 1/2" locks or lapped at least 3" in the direction of flow. Batten caps should be formed of the same weight as the underlying pan.

Special Conditions: For roof slopes less than 4" per foot, or areas where ice, snow or heavy rain conditions occur see Roofing Systems — Special Roofing Design and Installation Considerations.

Decking Requirements: Any type of smooth, flat roof deck.

8.3A. Gable Rake

A typical gable rake is shown. This detail shows the preferred method where a batten is set flush with the edge of the roof. In this case the cap is extended, effectively becoming a rake strip, and locked into the edge strip. An alternative method is shown in Detail 8.2B.

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8.3B. Ridge and Typical Batten Seam

This detail shows typical ridge and batten seams.

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8.3C. Finished Batten End — Process

The finishing process of the ends of battens is shown. The eave details for batten seams are otherwise similar to those for standing seam, as shown in Detail 8.2D.

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8.3D. Transverse Seams

The steep slope transverse seam shown is for roof slopes of at least 6" per foot. The low slope detail is for slopes less than 6" and greater than 3" or where additional protection desired.

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Cleats may be used at transverse seams to facilitate installation and restrict movement for pans 10' or less in length.

8.3E. Detail at Ridge and Batten

This detail shows two alternative methods of finishing the joint between a vertical batten and a ridge batten. Both details achieve the proper seal with extensions to the upstanding legs of the pans.

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In Alternative 1, shown in the middle, this extension is folded. This fold diverts water that has penetrated the vertical joint out onto the roof. Alternative 2 shows this extension lapped and soldered. The solder provides a watertight seal.

8.3F. Detail at Valley

Two alternative methods of detailing a valley condition are shown. Both require a 6" minimum lap of the roofing over the valley flashing. The one shown on the left uses a continuous locking strip soldered to the valley flashing. The other uses a double fold in the flashing to receive the ends of the roofing.

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The ends of the wood battens terminating at the valley are undercut to allow the folded edges of the valley flashing to pass underneath. The ends of the battens are covered with copper as described in Detail 8.2C.

8.3G. Alternate Cleat Types

These types of cleats may be used with batten seam roofs. The type shown on the left must be placed during batten installation. The type on the right is attached to the installed battens with copper nails before or after batten installation.

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Table 8.3A. Typical Batten Spacing for 1/2" Locks
Width of Sheets Batten Spacing (Inches) Recommended Copper Wt.
Square Battens Tapered Battens
18 14-1/8 14 16
20 16-1/8 16 16
24 20-1/8 20 20
30 26-1/8 26 20
36 32-1/8 32 20
Assuming 1-1/2" high battens

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