Wet insulation is the quiet cost on a flat roof. It does not always leak into the building, but it makes the roof heavier, weaker and shorter-lived, and it sets up the next failure. An infrared survey finds it. Done at the right time of day, a thermal camera shows where the roof holds heat longer than the dry areas around it, and a set of core cuts confirms which spots are actually wet. The product is a map of dry and wet zones with core locations and photos. Property managers use it to decide between a local repair, a recover and a full replacement, and to avoid paying to tear off insulation that is still sound.
How the Survey Works
Wet insulation stores heat. After a sunny day, as the roof cools toward evening, wet areas stay warmer than dry ones, and an infrared camera picks up the difference. We scan the roof in a grid, mark the warm patterns on the surface with paint and photograph them. The scan is done at dusk or after sunset on a dry day, since rain, wind and cloud cover wipe out the contrast.
The scan does not prove anything on its own. Equipment, color changes, ballast and roof layers all affect the readings. That is why we follow it with a moisture meter pass and core cuts. A core is a small plug removed from the roof, which shows the layers, the insulation and any water directly. Each core is patched and sealed the same day.
Surveys are best planned a week or two ahead. Roof access has to be arranged, the forecast has to cooperate and the superintendent needs to know that cores will be cut and sealed. We bring the sealing materials, the plan and a cleanup kit, and we leave the roof tidy. If conditions turn bad on the day, we stand down rather than collect weak data that could send a repair to the wrong spot.
Where It Pays on Bronx Buildings
Surveys earn their fee on roofs with a suspected moisture problem and on roofs facing a big decision. Apartment buildings in Concourse, Belmont and Longwood are pre-war, and a building's age says little about its roof. Where a roof does carry several layers, wet insulation in the middle can be invisible from above. A survey shows whether a recover is possible or whether the layers must come off.
Industrial roofs benefit too. The food district at Hunts Point shows why: the Cooperative Market spreads 700,000 square feet of refrigerated space over six main buildings, and the produce market adds four more. Cold interiors drive vapor toward the roof, and moisture can collect in insulation even without a leak. A survey on a cold-storage roof shows where condensation has done damage.
Core Cuts and What They Tell Us
Cores answer the questions the camera cannot. A core reveals how many layers the roof has, what insulation sits in it, how the deck surface looks and whether any water is inside the insulation, between layers or above the deck. They also show whether wet material is local, such as under a flashing, or spread across a broad area.
We choose core locations from the scan: a few in warm zones, a few in cool zones for comparison and a few at areas of known leaks. Each core is photographed and logged on the roof plan. Results are described in plain terms: dry, damp or saturated. For a roof that may carry a new system, the cores also tell us whether the existing deck and insulation can support a recover.
Timing a Survey in a Bronx Year
Good survey conditions are a clear, dry day with sun on the roof, followed by a calm evening. Central Park records show mean July highs near 95.7 F, and summer and early fall offer the best chance of strong contrast. Winter surveys are harder, since snow, ice and low sun reduce the signal, and an average winter at Central Park brings about 29.8 inches of snow.
After a big storm, a survey can map where water went. After Ida in September 2021, when 3.15 inches fell in one hour, roofs that held water for days can show wet insulation under the low spots. A roof that already ponds has ponding water repair to plan, because moisture and ponding tend to appear together.
Seasonal swings matter for another reason. Roofs expand in summer heat and contract in cold, and wet insulation under a membrane can freeze and thaw repeatedly, which loosens adhesive and fasteners. A survey in late summer or early fall shows the damage from the previous winter and gives you time to plan work before the next one.
From the Map to a Decision
The map turns into three possible paths. If the wet area is small, we cut it out and replace the insulation, then flash and patch the membrane, which is a targeted repair. If the wet zones are moderate and the rest is sound, a recover with local replacement may fit. If wet insulation is widespread, the roof needs a full replacement.
The survey also helps with budgeting. Because the wet area is measured, replacement quantities can be priced for the actual square footage instead of a blanket assumption. For a portfolio, surveys feed the due diligence roof survey that lenders and buyers ask for before closing.
Keep the map. Moisture zones change slowly, so a survey today is a baseline for the next one. Repeating the scan every few years on a roof you intend to keep shows whether the wet areas are growing, and that growth rate is a better predictor of replacement timing than the roof's age alone. It also gives a clean before-and-after record after any insulation replacement.
Commercial Roofing Questions
Can an infrared scan find wet insulation under a gravel-surfaced Bronx roof?
It can, though gravel and ballast dampen the signal, because heat moves through stone differently. On those roofs we lean harder on the moisture meter and core cuts. The scan still helps us choose where to cut, and the cores confirm the findings. Expect a few more cores than on a smooth membrane.
How many core cuts will you make, and who repairs the holes?
A handful on a typical building, placed in warm, cool and suspect areas, with more on large or complex roofs. We patch and seal each hole before leaving the roof, so no new leak path is created, and each repair is logged on the roof plan.
Will the survey tell me how much insulation to replace?
It gives a measured estimate. The map shows the extent of wet zones, and the cores confirm the depth. We mark the boundary on the roof and quantify it in square feet. Final quantities can shift once the roof is opened, and the report says so up front.
Does a cold-storage building in Hunts Point need a different approach?
Cold interiors can pull moisture upward and condense in the insulation even with no roof leak. For that reason we look at how the roof was built, where the vapor retarder sits and how the building operates. Scan timing and core choices change to fit the building.
When is a survey not worth the money?
Skip it when the roof is clearly at the end of its life and replacement is already decided, or when a very small roof has one obvious leak. For everything in between, a survey usually pays for itself by narrowing the repair to the area that is actually wet.
Send the Roof Type and the Decision You Face
Tell us the building type, the roof age and the choice in front of you: repair, recover or replacement. We will schedule a scan at the right hour and send a map you can budget from.
Request a Roof Assessment