How to Install Cornice & Siding

Proper Order

• Building occurs in a specific order when constructing a home. General framing of the house including the wooden stud interior and the exterior layout of the floors, ceiling, roof, decks and porches occur first. Cornices and siding are installed after windows, doors, roof paper and sheathing are in place. Cornices, often made of fiberglass, are installed before siding. Roofing is installed after the cornices. Vinyl or aluminum siding can be installed by homeowners, but fiber cement siding is difficult to hang and should be installed by professionals.

Cornice Installation

• Before the actual cornice installation, all exterior crown molding and siding joints must be properly fitted, and lamb legs are made symmetrical and soffit vents are properly installed. The lap joints of cornice sections, typically found on the right side of each piece should be sanded, and countersink holes should also be present. Installation begins on the left corner of a building and continues to the right. Lap joints receive light caulking before the cornice section is secured through galvanized or stainless steel screws. An application of paintable or color-matched sealant finishes cornice installation.

Additional Trim

• After cornices are installed and before hanging siding, other exterior elements are put in place, starting with high trims, such as rakes and fascia, which help hold together other building elements. Other elements that should be installed before the siding are corner posts, light blocks, dryer vents and arches. Flashings around windows and doors should be installed first, followed by J-trim, which the siding will tuck under when it is installed. Installers should allow for at least ¼-inch of material expansion during hot weather.

Siding Installation

• Installation for all types of siding starts at the bottom of the building and continues upward. Starter strips are put at the bottom of each exterior wall. The initial siding panel is nailed into this strip, with ¼-inch to ¾-inch allowance for heat expansion necessary for vinyl and fiberglass. Galvanized, stainless steel or aluminum roof nails secure siding panels to exterior walls, with a 1- to 1-1/4-inch overlap for each panel. Siding needs to have ¼-inch gaps where it butts against other building elements such as the cornices. Proper siding installation has staggered joints and lapping that faces away from building entrances as well as the street. A portion of the last siding panel usually, but not always, needs to be cut to fit before it is installed with a snap lock tool.