Roof Recover Overlay

Roof recover — installing a new membrane system over an existing one without a full tear-off — is one of the most consequential decisions in commercial roofing, and in Wilmington's coastal climate it requires more discipline than in drier markets. The fundamental requirement of any recover is a dry, structurally sound substrate beneath the new system. In a market that receives 60 inches of annual rainfall and has experienced repeated tropical storm events that breach roof membranes and drive water into the insulation layer, the likelihood that a commercial roof's insulation is wet — sometimes significantly wet — is higher than most inland markets. A recover performed over wet insulation traps moisture in the assembly, degrades the new system's adhesion over time, accelerates deck deterioration beneath the insulation, and produces a roof that will never perform correctly regardless of the quality of the new membrane installed on top. We require moisture verification before any recover recommendation, and we mean it.

Infrared thermal scanning and core sampling are the diagnostic tools that determine whether a recover is viable. Infrared scanning maps moisture distribution in the insulation layer across the entire roof field — identifying wet zones with the thermal differential between wet and dry insulation that the camera detects after a sunny day. Core sampling at locations identified by the scan and at control locations in apparently dry areas provides physical confirmation. The combination of scanning and cores gives us an accurate, documented picture of insulation moisture distribution before any recover decision is made. When moisture is localized — less than roughly 25 percent of the roof area — selective tear-out and replacement of wet sections, followed by recover of the full roof area, is a legitimate approach. When wet insulation is widespread, a full tear-off is the only honest answer, and we present it as such.

The International Building Code limits commercial buildings to two roofing layers. Many of Wilmington's older commercial buildings — particularly those in the downtown corridors, along Oleander Drive, and in the original Northchase development — already have two existing layers from previous re-roofing projects conducted over the past 20 to 30 years. On these buildings, a recover is not legally permissible regardless of the insulation moisture condition, and the project must proceed as a full tear-off and replacement. We verify the existing layer count during our pre-project assessment and communicate that determination clearly before a recover is proposed. Discovering a second layer after the project has started — because the existing assessment was inadequate — is an avoidable problem that causes budget and schedule disruption for the building owner.

Pre-hurricane season timing for recover projects in Wilmington is an important scheduling consideration. A recover that installs a new membrane over an existing system in May, allowing the new membrane to cure and acclimate before hurricane season begins in June, is a significantly better outcome than a recover that is still in progress when the first tropical system of the season approaches. We plan recover project schedules with hurricane season timing in mind and communicate with commercial property owners about the risk of starting a large recover project that cannot be completed before June without leaving the building in a partially open condition during storm season. For large roofs where the recover will take multiple weeks, phased scheduling that keeps each completed section fully watertight as work progresses is essential.

Recovery board selection matters for the long-term performance of the new system. Recovery board — typically high-density polyisocyanurate or glass-mat gypsum board — provides a clean, flat substrate for the new membrane, adds R-value to the assembly, and compensates for minor irregularities in the existing membrane surface that would telegraph through a new single-ply membrane. In the Wilmington market, where recover projects are frequently going over aged modified bitumen or BUR systems with uneven granule surfaces and minor ridging, a recovery board that bridges those irregularities is important for the new membrane's adhesion quality and appearance. We specify recovery board type and thickness based on the existing substrate condition and the new membrane system being installed over it.

Perimeter and flashing details on recover projects require complete replacement — not reuse of existing flashing components. This is a point of discipline that matters enormously in Wilmington's salt-air coastal environment. An existing aluminum termination bar that is partially corroded, or an existing edge metal that has corroded at its fastener holes, is not a sound base for new flashing details even if it appears adequate for the moment. The new membrane system will be expected to perform for 20 years. Reusing corroded edge metal on a coastal building means that the new system's perimeter performance degrades in 5 to 8 years when the old metal reaches the end of its life. We replace all perimeter metal, termination bars, and counterflashings as standard scope on every recover project — not as an optional upgrade.

Recover projects on occupied commercial buildings in downtown Wilmington and active retail corridors present logistics considerations that differ from industrial sites. Downtown buildings have limited staging areas, narrow street access, and neighboring properties in close proximity. Debris from existing membrane removal — limited in a recover compared to a full tear-off, but still present — must be managed carefully. Noise and disruption from membrane installation equipment, particularly hot-air welding of single-ply systems, requires coordination with building tenants and neighbors. We plan project logistics in advance, communicate with building managers and tenants, and schedule the most disruptive work phases during hours that minimize business impact.

Single-ply membrane recover over existing modified bitumen or BUR is the most common recover configuration we execute in the Wilmington market. TPO is the predominant choice for its reflectivity, weld-quality seam system, and manufacturer warranty availability. Installation of mechanically attached TPO over a recovery board on an existing modified bitumen system is a well-established configuration with a strong performance track record. Fully adhered TPO provides better wind uplift resistance and is specified on projects where the building's location or exposure warrants the additional uplift performance — a consideration we take seriously on any Wilmington commercial building given the hurricane exposure. The attachment method decision is made based on the building's structural characteristics, existing substrate condition, and uplift design requirements.

Warranty coverage on recover systems is available from major TPO and single-ply manufacturers when installation meets their specifications for substrate preparation, recovery board selection, and attachment method. We complete manufacturer registration for every warranted recover project and maintain the documentation record that warranty claims require. Commercial property owners who invest in a recover system without manufacturer warranty registration have only contractor workmanship coverage — which is a significantly weaker protection than a manufacturer-backed system warranty, particularly in a market where storm events can trigger warranty-relevant damage scenarios.