A recover-versus-replace decision without moisture data is a guess. Core sampling and moisture mapping tell you how much of the insulation is wet and where — the numbers that drive the honest scope recommendation.
The single most expensive mistake in commercial roofing is recovering a roof with wet insulation. A recover installs a new membrane over the existing system — if the insulation below is saturated, the moisture is now trapped. The new membrane warrants fine. The wet insulation continues to degrade. The deck below it eventually corrodes or rots. Five years after the recover, the building needs a full tear-off of the new membrane plus the old membrane plus damaged insulation plus possibly deck replacement — a project that costs two to three times what a full replacement would have cost at the original decision point.
Moisture survey is the tool that makes the recover-versus-replace decision supportable with data. We core-sample roofs to pull physical evidence of insulation condition at representative locations across the roof area. We map the distribution of wet zones to understand both the percentage of the roof area affected and the spatial pattern — which tells us whether the moisture is from a single discrete leak source or from multiple distributed sources.
Dallas roofs have specific moisture patterns driven by how they were built and how they have aged. The Stemmons and Garland industrial stock from the 1980s and 1990s often has moisture in concentrated zones around drains and at parapet walls — the original drain flashings failed incrementally over years and the moisture migrated outward. The Class A office buildings from the same era often have moisture at penetration clusters where equipment has been added or repositioned over decades. Knowing those patterns tells us where to sample for statistical confidence on each building type.
We pull cores with a 4-inch diameter core cutter at representative locations identified before the site visit by review of the existing inspection record, drain layout, and building history. Each core pulls through the membrane and the full insulation stack to the deck surface. We record the number of plies (for multi-ply systems), the insulation type and thickness, the condition of each layer, and whether the insulation is wet, damp, or dry by direct physical assessment.
Core density: The statistical confidence of a moisture survey depends on the number of cores relative to the roof area and the suspected moisture distribution. For a 50,000 sq ft roof with no prior moisture data, we pull a minimum of 15-20 cores in a grid pattern plus targeted cores at high-probability locations (drains, parapet returns, penetration clusters). For a roof where prior inspection has identified specific suspect zones, we pull cores in those zones at higher density and confirm with scattered cores in presumed-dry areas to establish the extent of moisture migration.
After pulling, each core location is repaired with membrane-matching material and resealed. The core locations are logged on the zone diagram by number so the owner has a permanent record of where each core was pulled and what it found. This matters for future inspections — if a core at a specific location came back dry in 2024, the next inspection can pull the same location to assess whether conditions have changed.
The core results are plotted on the zone diagram to produce a moisture distribution map. Wet cores, damp cores, and dry cores are marked distinctly. The map shows the spatial pattern — clustered moisture suggests discrete leak sources; dispersed moisture suggests systemic saturation from multiple years of diffuse infiltration.
The 25% threshold is the conventional recover-versus-replace decision point: if more than 25% of the roof area has wet or significantly damp insulation, recovering is not an honest scope. The recover manufacturer will not warrant a system installed over wet insulation, and the trapped moisture will continue to degrade the deck below it. Below 25%, a selective-tear-off recover — where wet areas are torn off to the deck, the deck is inspected and repaired if needed, and only those areas get new insulation before the recover membrane goes on — is a legitimate capital option that typically costs 40-60% of full replacement.
We present the decision analysis in writing with the moisture map and the core data as supporting documentation. The recommendation is recover-option, full-replacement, or (rarely) a staged approach where the most critical sections are replaced now and the remainder is deferred with a monitored timeline.
