How much of this roof is actually wet?
A roof moisture survey answers that with a drawing, so you replace the sections that failed instead of the whole roof.
Why the answer is worth paying for
Roofs get condemned on a handful of interior stains and a contractor's estimate. A survey replaces that with evidence: here is the wet area, here is the dry area, here is the line between them.
Sometimes that turns a tear-off into a sectional replacement. Sometimes it confirms the roof really is finished, and then you are spending the money on proof rather than on a hunch. Either way the survey costs a fraction of the difference between those two outcomes.
Both find wet insulation. They fail in different ways.
Infrared reads temperature. Nuclear reads hydrogen. Neither is the better method in general, and a firm that owns one will tell you otherwise.
Sees the whole roof. Needs the right night.
Wet insulation stores more solar heat through the day and gives it up more slowly after dark, so it glows against the dry roof around it. Its real advantage is coverage: a thermal scan looks at 100% of the surface, not a sample of it, quickly and economically across very large areas.
It reads temperature, not water. Rooftop equipment and warm penetrations can look like moisture, and a bright reflective cool roof can hide it. It needs real solar gain, a decent day-to-night temperature swing, low wind, and no rain in the previous 24 hours. Ballast and pavers stop it entirely.
Infrared roof moisture surveys NuclearReads through anything. Samples rather than sweeps.
The gauge counts hydrogen, which in a roof means water, and it does not care about sun, shade, reflectivity, weather or time of day. It reads deeper into the assembly, so it finds moisture under overlays and cover boards that a thermal scan cannot reach. Readings are taken on a grid, usually 10ft by 10ft.
Nuclear roof moisture surveys Very often, bothOne finds it. The other confirms it.
Infrared across the whole roof to locate the suspect areas, then nuclear on those areas to confirm them without cutting anything. Where the decision is large enough, cores verify what both instruments indicated.
The full comparisonWorth knowing, because it is the part most surveys skip: ASTM C1153, the standard covering infrared roof surveys, requires that anomalies be verified rather than acted on. A thermal image on its own is a list of places to look, not a finding. Nuclear surveying runs to ANSI/SPRI/IIBEC NT-1, and its field readings are comparative until they are correlated against cores.
That is why we carry both instruments and will tell you when a survey needs verifying. A report that presents unverified thermal anomalies as wet roof is the one that falls apart when somebody else's engineer reads it.
What you get, either way
A marked roof plan with the wet and dry areas delineated and the boundaries drawn, in a form a roofer can price from and an owner can understand. The areas marked on the roof itself, so the crew is standing in the right place. The conditions on the day and the limits of the method stated in writing.
It is a map, not a verdict. We do not sell roofs and we do not do the repairs, so what the survey found is all the report says.