Trim and Siding Profiles

Fiber-cement is available as lap siding (12-ft. lengths from 5 1/4- to 12-in. wide), shingle panels (16x48-in.), and vertical or stucco-like panels (4x8, 4x9, and 4x10). Manufacturers also make trim boards and soffit panels.

Fiber-cement is much heavier than wood. Although the lap siding is typically only 5/16-in.-thick, it weighs about 2 1/4 pounds per sq. ft., making solo handling difficult. It’s also quite flexible, and full-length pieces can snap under their own weight. Always carry boards on edge rather than on the flat.

PVC trim is a good complement to fiber cement siding because of its rot-resistance. The 7/16-in. fiber-cement trim stock is not as good a nail-base for built-up exterior trim.

Aluminum/Cement Conflict

Portland cement is highly alkaline and can corrode most unprotected aluminum. The exception is anodized aluminum. Most manufactured aluminum window trim is anodized; most off-the-shelf aluminum flashings are not. As a precaution, prime the ends of fiber cement siding at field cuts near flashings or aluminum windows.

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