SMACNA guidelines on making Bermuda-type roofs.

Figure 6-11

The following is taken from the Sheet Metal and Air Conditioning Contractors’ National Association’s Architectural Sheet Metal Manual, Sixth Edition.

The Bermuda roof illustrated in Figure 6-11, 6-12 and 6-13 (not shown) is not recommended for roofs having a slope of less than 2 ½ inches per square feet.

Wood framing must be provided as shown in Detail No. 1, Figure 6-12. Dimension D and gauge of metal will depend on the size of sheet used (see Table 6-2 and Figure 6-11).

Figure 6-12

Before installation, the deck should be thoroughly dry and covered by a saturating roof felt. A smooth building paper should be applied over felt to avoid bonding between felt and metal and is required for copper.

Bermuda roofs are applied beginning at the eave. The first pan is hooked over a continuous cleat shown in Detail No. 2, Figure 6-12.

The upper portion of the first and each succeeding pan is attached as shown in Detail 3, Figure 6-12. Cleats spaced on 8-inch centers are nailed to batten as in (Detail No. 3’s) A. (The) joint is developed as shown in B and malleted against batten as shown in C. All cross seams are typically single-locked and soldered or appropriately waterproofed, except at expansion joints. Cross seams should be staggered.

Expansion joints should be used at least every 25 feet and formed as shown in Detail No. 4, Figure 6-12.

Roofing is joined at hip or ridge by use of a standing seam as shown in A of Detail No. 5, Figure 6-12. Seam may be malleted down as shown in B.

Table 6-2: Recommended gauges and pan widths for Bermuda roofs