Wall Covering Trim

Wall Covering Trim


Trim associated with exterior wall coverings can be functional, decorative, or both. Functional trim provides a consistent and stable surface against which wall coverings can terminate. Sealants are more effective and last longer when applied to a consistent and stable surface. Examples of functional trim include inside and outside corner trim, channel trim used with vinyl siding, and various styles of moldings and casing around windows and doors, such as brick molding. Examples of decorative trim include pediments above doors and windows and other facing materials. Decorative trim is often installed on top of the wall covering. Decorative stucco trim is usually installed under the stucco coating. Modern stucco trim is usually made from foam. Stucco trim on older buildings is usually made from wood.

Trim that is made from the same material as the wall covering and that is required to be used when installing the wall covering is evaluated as part of the wall covering inspection. Examples of this trim include J and F channel trim for vinyl siding. Decorative trim that is integrated into the wall covering is also evaluated with the wall covering. Examples of this trim include projecting trim around windows and doors installed with stucco, and decorative trim (such as pediments) installed with vinyl siding.

Trim made of materials different from the wall covering is evaluated as a separate, but related, component. Examples of this trim include wood and composite wood corner boards installed with wood-based siding and fiber cement siding, moldings and casings around windows and doors, and all attached decorative trim such as pediments above doors and windows and pilasters at the sides of doors.

Trim is not required, except when specified by the wall covering manufacturer’s installation instructions. Lack of trim where it is usually found, such as corner boards, may be an indication of deficient or amateur construction. These situations should be evaluated carefully, especially for signs of water infiltration.

Trim on buildings constructed before about 2000 is usually made from wood or wood-products and requires the same clearances to surfaces such as earth and concrete as any other wood product. Trim on recently constructed buildings may be made of engineered materials or PVC that look like wood but may not require the same clearances to surfaces as wood-based products.

Typical Defects Typical defects that home inspectors should report include:

  1. inadequate clearance above grade, hard surfaces, and roof coverings,
  2. absent and deteriorated sealant around doors and windows,
  3. damaged and deteriorated trim; deterioration often found near the bottom edge of the trim,
  4. trim slopes toward the house,
  5. absent or deteriorated paint at the bottom edge.

Standards Manufacturer’s instructions (for trim required by the wall covering manufacturer and for engineered trim).


Two images side by side. Caption below reads "Corner boards are often unpainted on the bottom resulting in deterioration. Corner board on right is too close to the roof covering, and is deteriorated."
Caption below reads "Watch for trim sloped toward the house."