All portions of the exterior finish, other than the wall covering, are generally classified as exterior trim. This includes the moldings and sills around windows and doors, fascia boards, soffits, louvers, shutters, and decorative columns. (See FIG. 5-5.) Trim does not serve a structural function. It is used as finishing around openings and to protect joints, edges, and ends. Most exterior trim is made of wood or wood products, although aluminum and vinyl trim have become quite popular. Many older, traditionally designed homes have decorative sheet-metal cornices, which are considered part of the trim. The problem with sheet-metal trim is that if it is not maintained and kept adequately painted, it will rust and deteriorate.
Fig. 5-5. Exterior trim on a house: A-gable louvers, B-fascia, C- soffit, D-shutters, E- widow’s walk balustrade, F-decorative columns.
Wood trim that is exposed to the weather should be decay-resistant so that it does not rot. (See the section on rot in chapter 8.) Some types of preformed trim are factory-treated with a water-repellent preservative to make them water- and decay-resistant. When the trim is cut to size during construction, the ends or miter joints must be treated to make them water-resistant. All too often they are not treated, and the joints, which readily absorb water, begin to rot. When inspecting wood trim, pay particular attention to the joints that are vulnerable to decay. A house with a wide roof overhang at the eaves and gables provides greater weather protection of the sidewalls and trim than one with no roof projection beyond the walls. All nontreated wood continually exposed to moisture is prone to decay. The trim around the edge of the roof is particularly vulnerable. Although the Asphalt Roofing Manufacturers Association recommends the installation of a metal drip edge along the eaves of a roof deck, in practice it is often omitted. The drip edge is designed to allow water runoff to drip free of the underlying trim. Without it, water tends to curl back under the shingles, wetting the edge of the roof sheathing and trim.
Wood trim should be inspected for cracked, loose, missing, and rotting sections. If the trim is painted, is the paint peeling and flaking in sections? Does the trim need repainting for weather protection? In older Tudor-style houses with timbers embedded in the stucco siding, inspect the timbers at the stucco joints for decay, especially if the joint is horizontal. Over the years, the joints tend to open slightly, allowing water to penetrate. With nonwood trim, check for loose, missing, and deteriorated sections.