A roof can look fine from the surface while the insulation beneath it is soaked — and a roof moisture survey is how you find that hidden water before you decide whether to patch, partially replace, or reroof.
When a low-slope roof leaks or ages, the critical question is often invisible from the surface: how much of the insulation under the membrane is wet, and where? Wet insulation loses its thermal value, adds weight, corrodes fasteners, and keeps a roof deteriorating even after a surface repair. A roof moisture survey answers that question without tearing the roof apart, using non-destructive methods to locate the moisture and map it. That map is what lets an owner decide intelligently between a spot repair, partial replacement, and a full reroof.
The value is in seeing the unseen. The sections below cover the four aspects that matter most — finding wet insulation you can’t see, infrared, nuclear, and capacitance methods, mapping the roof for targeted repair, and survey timing and conditions — and how ACE approaches roof moisture surveys.
These challenges rarely stay in one silo: the same discipline runs through the same playbook behind building envelope commissioning, lessons from preconstruction mock-up testing, and our guidance on electronic leak detection, and it all ladders up to ACE’s broader forensic building-envelope investigation.
Finding wet insulation you can’t see is the entire purpose of roof moisture surveys, because water that enters a low-slope roof soaks into the insulation and spreads laterally, staying hidden under an intact-looking membrane while it destroys thermal value, adds weight, and corrodes fasteners. Locating that hidden moisture is what a survey does before any decision is made.
Wet insulation keeps a roof failing even after surface leaks are patched, since the trapped water continues to damage the assembly and never dries under the membrane.
Because the moisture is invisible and consequential, finding it non-destructively is the necessary first step to any informed repair or replacement decision.
Representative of how ACE's roof moisture surveys guide roof decisions. Illustrative distribution, not a published statistic.
Infrared, nuclear, and capacitance methods are the three main survey techniques, and each detects moisture differently, because infrared thermography reads temperature differences from the heat wet areas retain, nuclear meters detect hydrogen in the moisture, and capacitance meters sense the electrical effect of water. Choosing the method or combination that suits the roof and conditions is what produces reliable results.
Infrared covers large areas efficiently and is often used to screen a roof, while nuclear and capacitance meters confirm and quantify at specific points, so the methods are frequently combined.
Because no single method is perfect for every roof, understanding what each measures and where each is reliable is part of surveying a roof accurately rather than misreading it.
A roof leaks or ages and the wet insulation beneath the membrane is invisible, so repair or reroofing decisions are made by guesswork.
Survey the roof non-destructively with infrared, nuclear, or capacitance methods under suitable conditions, and map the wet and dry areas.
The owner gets a reliable moisture map and can target repair or replacement precisely instead of over- or under-spending.
Mapping the roof for targeted repair is what makes a survey actionable, because the survey produces a map showing where the insulation is wet and where it is dry, so repairs and replacement can be targeted precisely instead of guessing or replacing everything. A moisture map turns a reroofing decision into an informed one.
With the wet areas mapped, an owner can weigh a targeted repair against partial or full replacement based on how much of the roof is actually compromised, rather than on assumption.
Because the map distinguishes wet from dry, it often reveals that far less — or far more — of the roof needs replacement than expected, which directly affects cost and timing.
Ask about a roof moisture survey to map the wet insulation before you patch, replace, or reroof.
Schedule a consultationCall (866) 389-8883Survey timing and conditions strongly affect the results, because several of the methods, infrared especially, depend on temperature differences and dry surface conditions, so surveys are scheduled for the right weather and time of day to produce reliable readings. Conducting the survey under suitable conditions is what makes the results trustworthy.
A survey run in the wrong conditions can miss moisture or give false readings, which is why timing is treated as part of the method rather than an incidental detail.
The most valuable aspect overall is that a properly conducted roof moisture survey replaces guesswork with a reliable map of the roof’s condition, letting owners spend repair and replacement budgets where the moisture actually is.
In ACE’s field work, most roof moisture surveys problems trace back to a few recurring locations — Extent of wet insulation, Repair vs. reroof decision, and Targeted replacement areas — rather than the open field of the wall or roof. The cost of resolving them climbs by roughly an order of magnitude at each stage: a detail corrected during design costs a fraction of the same fix during construction, which is itself far cheaper than a repair once the facility is operating. That economics is why we push envelope decisions as early in the project as possible.
Choose infrared, nuclear, capacitance, or a combination for the roof, and schedule the survey for suitable weather and time of day.
Scan the roof non-destructively to detect where the insulation is wet, confirming and quantifying at specific points as needed.
Map the wet and dry areas so repair, partial replacement, or full reroofing can be targeted precisely rather than guessed.
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