Long-form guide · 9-minute read
Thermal imaging. Sees moisture through walls and floors.
Infrared thermal imaging detects the temperature differential caused by water moisture in walls, ceilings, floors, slabs, and façades. A FLIR-grade camera turns invisible moisture into a clear visual map — non-contact, non-invasive, and devastating to anyone hoping to hide a leak.
What is thermal imaging leak detection?
Thermal imaging — also called infrared thermography — uses a specialised camera that detects infrared radiation (heat) emitted by every surface. The camera converts the temperature differences across a scene into a colour image where warm areas appear bright and cool areas appear dark. For leak detection, water that's evaporating cools the surrounding surface; water that's warmer than the surrounding material (e.g. a hot-water leak) shows up bright.
Modern leak-detection thermal cameras (FLIR T-series, Fluke Ti, or equivalent) have sensitivities of 0.05 °C or better — they can detect a 1/20-of-a-degree temperature difference, which is far more than enough to map wet vs. dry on a wall, ceiling, or slab. The trick is interpreting the image correctly: not every cool spot is a leak, and the technician's experience matters as much as the camera's specs.
Thermal imaging is typically the first technology deployed on any non-invasive leak investigation. It rapidly maps the area of concern, then narrows it to specific zones where confirming technologies (moisture meter, acoustic, GPR) are used. It's also used in many adjacent applications: insulation gap detection, electrical hot-spot inspection, pre-restoration documentation, and façade investigation.
When you need thermal imaging leak detection
If you're seeing any of these signs, professional detection is warranted:
- Visible stain, mold, or moisture on a wall or ceiling
- Warm spot on a floor (hot-water slab leak)
- Cold draft suggesting insulation failure or window leak
- Suspected wall-cavity moisture before drywall closure
- Pre-restoration documentation of damage extent
- Insurance claim requiring quantitative moisture documentation
- Façade investigation on a high-rise (drone-mounted thermal)
- Real-time site verification during repair
Thermal sees what your eyes can't
By the time water damage is visible to the naked eye, the moisture has been present for days or weeks and has spread well beyond the visible stain. Thermal imaging maps the true extent of moisture — often 3–10x the visible area — letting you scope a complete repair instead of a patch that misses 80% of the wet zone.
How we detect it
- 1
Pre-survey
Equalise the building environment if needed (HVAC off, blinds closed). Thermal works best with stable thermal conditions and good differential between materials.
- 2
Wide-area scan
Walk the area of concern with the camera in real-time. Identify thermal anomalies that warrant closer investigation.
- 3
Zone narrowing
On suspected wet zones, the camera is held in place to confirm the anomaly is stable (vs. transient draft or shadow).
- 4
Moisture-meter confirmation
A pin or pinless moisture meter is used at the thermal anomaly to confirm wet drywall, framing, or floor — turns the visual into a quantitative reading.
- 5
Multi-technology integration
If a pressurised supply leak is suspected, acoustic listening at the wet zone confirms. If a structural concern, GPR identifies pipe and rebar layout.
- 6
Annotated report
All thermal images are saved with location codes, date/time stamps, equipment manifest, and technician credentials. Report is formatted for insurance review.
Detection technologies we use
FLIR Thermal Camera (T-series)
Professional handheld infrared camera. 0.05 °C sensitivity, 320×240+ resolution, simultaneous visible-light overlay.
Moisture Meter (pin + pinless)
Confirms thermal anomalies with quantitative moisture content readings. Standard partnership tool with thermal.
Drone Thermal
Aerial thermal payload for façades, roofs, and large properties. Eliminates scaffolding cost.
Learn moreAcoustic Listening
Pairs with thermal for pressurised-leak confirmation. Listen at the wet zone — water under pressure makes a distinctive sound.
Learn moreCommon scenarios
Residential ceiling leak
Brown stain on living room ceiling. Thermal mapped the wet zone — 3x the visible stain area. Located leak source: upstairs shower pan, 4 metres from the visible stain. Repair scope correctly identified on first try.
Commercial post-restoration verification
Restoration contractor claimed area was dry after remediation. Thermal scan identified residual moisture in two wall cavities that were missed. Re-remediation prevented mold re-growth claim 6 months later.
High-rise façade investigation
30-storey condo had recurring water on south face. Drone-based thermal scan identified curtain-wall infiltration at three window head flashings — saved a misdiagnosed (and unnecessary) roof inspection.
Typical pricing
Typical range. Final price quoted on the free phone consult.
- Single-area thermal survey: $300–$500.
- Whole-house or whole-building thermal survey: $500–$900.
- Drone façade thermal: separately priced under drone services.
- Often combined with other technologies — final price quoted in phone consult.
Frequently asked questions
Does thermal imaging really see through walls?
Thermal sees the temperature pattern *on* the wall surface caused by what's behind it. Water in a wall cavity changes the surface temperature in a detectable pattern, especially for hot-water lines. It's not 'x-ray vision' — but reliably good at finding wet areas, voids in insulation, and active electrical hot-spots.
What's the sensitivity of your thermal camera?
FLIR T-series or equivalent at 0.05 °C or better — sensitive enough to detect a fingerprint on a wall after a few minutes. For leak detection, the wet/dry temperature differential is usually 0.5–3 °C, well within range.
Can thermal imaging find leaks under concrete slabs?
Yes, especially for hot-water leaks where the heated water creates a clear thermal plume through the slab. Cold-water slab leaks are harder but typically still detectable. Best to combine with acoustic correlation for slab leaks.
When is thermal imaging not the best choice?
Thermal struggles when there's no temperature differential (e.g. cold-water leak in a cold ambient slab), when the leak is deep underground (more than ~1 m), or when surface conditions are highly variable (windy outdoor surveys). For these, acoustic, GPR, or tracer gas are better fits.
Will thermal images stand up in an insurance claim?
Yes. Thermal images with location codes, timestamps, equipment manifest, and technician credentials are standard insurance documentation. All major BC insurers accept thermal-based leak reports on first review.
Can you do thermal imaging on a commercial building during business hours?
Yes — thermal is non-contact and silent, perfect for occupied buildings. Often best done with HVAC stable (no recent thermal changes) which usually means early morning or after operations.
Do you do thermal scans on building envelopes?
Yes — both on residential homes (energy efficiency, air leakage, insulation gaps) and on commercial buildings (façade investigation, often paired with drone thermal). Comprehensive envelope reports are a major part of our work.
What's the difference between thermal imaging and infrared thermography?
Same thing — different terminology. 'Thermal imaging' is the common name; 'infrared thermography' is the formal/engineering term. Same technology, same cameras.
Can thermal find a gas leak?
Not directly — gas isn't temperature-distinct unless it's a refrigerant leak that produces local cooling. For natural gas or propane, we use combustible gas detectors and tracer gas. For active gas-smell emergencies: leave the building and call 911 or FortisBC 1-800-663-9911.
How long does a thermal survey take?
Single-area: 15–30 minutes. Whole house: 1–2 hours. Whole commercial building: 3–6 hours. Drone façade scan: 30 minutes plus 1 hour analysis. Written report within 24 hours.
Related guides & services
Drone Inspection Services
Hidden Water Leak Guide
Slab Leak Detection Guide
Roof Leak Detection Guide
Compare: Acoustic vs Thermal vs GPR
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