Core Sample

Cutting Through to the Truth

A core sample is a small cylindrical section cut vertically through all layers of a flat or built-up roof system, from the surface membrane through the insulation to the deck, then extracted and examined to reveal material types, layer count, moisture conditions, and hidden damage. On flat roofs where the roofing assembly is multi-layered and concealed, a core sample is often the only way to determine what is actually there and what condition it is in. The information gained from a core sample directly affects the accuracy of the Xactimate estimate.

Core samples convert assumptions into verified facts.

What a Core Sample Reveals

Extracting a core sample from a flat roof reveals: the type of surface membrane (BUR, modified bitumen, TPO, EPDM), the number of roofing layers (important for tear-off costs), the type and thickness of insulation, the condition of the insulation (dry, damp, or saturated), the type of roof deck, and any evidence of prior repairs or re-covers. Each of these details affects the estimate. A two-layer BUR system costs significantly more to remove than a single-ply membrane. Saturated insulation that must be replaced expands the scope beyond just the membrane.

Photograph the extracted core sample with a ruler for scale and label the layers clearly.

Core Samples and Insurance Claims

Core sample data strengthens claims in multiple ways. If infrared scanning identified moisture, the core sample confirms it with physical evidence. If the carrier's estimate assumed one layer of roofing, the core sample proving two layers justifies the additional tear-off cost. If the insulation is saturated and must be replaced, the core sample proves the need. Always take core samples in areas identified by infrared scanning as potentially problematic, and take control samples in areas that appeared dry for comparison. The contrast between wet and dry samples is compelling evidence.