By: Joe Czaszynski

Wood trim deterioration is a common site, especially on aging buildings. Window casings, door casings, corners, frieze, baseboards, soffits, rakes, fascia, etc. are all integral parts of a façade that are made of wood. When these wood trim components deteriorate or rot, it can be very unsightly and costly to building owners. Trim deterioration often results from improper trim or sealant installation, flashing issues, or improper maintenance.

Trim should never be installed directly against other horizontal building components, such as: roofs, decks, balconies, terraces, etc., nor come in contact with built-up grade or mulch. A gap between the trim and these components will allow water to properly flow away from the building and its components. If trim is installed too tightly, trapped water can deteriorate both the trim and adjacent building components.

Misuse of sealant above windows and doors where flashings already exist can cause problems. Water is meant to exit through some open joints. If these joints are sealed, water will become trapped behind the trim, the siding or the façade. Typically, the backside of the trim and siding is not waterproofed. Trapped water will quickly deteriorate the wood trim and siding it comes in contact with, and eventually infiltrate the building façade. Deterioration on the exterior face often indicates a water infiltration issue.

Flashing materials must be properly installed around or behind building trim. Since the majority of the flashing is behind the trim or siding, it can only be assessed when the trim or siding is removed. When it becomes necessary to replace the trim, it’s important to have a qualified professional confirm the presence of correctly installed flashing that is properly diverting water out from behind the façade.

Once the paint or stain is compromised, the trim will absorb water rather than shed it. Therefore, proper maintenance is imperative in preventing accelerated deterioration. To defend against the elements, wood trim requires painting or staining approximately every three to six years.

A maintenance plan that includes regularly scheduled painting and staining, along with periodic inspections for irregular deterioration, can prevent the need for trim and siding replacement. Additionally, once trim deterioration is observed, a building envelope consultant should be retained to perform an inspection, evaluate the cause, and provide recommendations for remediation. If the trim is not replaced and the water infiltration issues are not addressed, additional damage to the building façade and components often

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