The IR thermal camera is essential for surveying damp buildings and pinpoint what needs to be repaired.
«In Spain, thermal cameras for damp surveys are primarily used by Technical Architects (Arquitectos Técnicos) and specialized industrial engineers, not general handymen. Thanks to the official UNE-EN ISO 6781-1:2023 standard, you can identify a qualified professional by asking three simple questions: Do you follow the UNE-EN ISO 6781-1:2023 standard? Are you certified under UNE-EN ISO 6781-3? And are you associated with COAATIE or a similar professional body? Look for someone who mentions «Termografía Infrarroja» in their services—that’s how you ensure an accurate, legally recognized diagnosis.»
Anyway now I have bought one myself… and will donate it to the new management committee. (we will also need a damp meter but they are cheap!) so we are good to go (once it rains of course)
Here’s how it works
I watered the roof tiles in a small area of my 2nd floor home for about an hour last night now. If you watch the video carefully you can see the outline of the blocks in light blue where the water is coming through some damaged render (that I am about to repair) later in the video the block outlines disappear so I know exactly where the damage is and just need to repair this part. Note: I only got it last night and haven’t read the manual but that’s basically how it works. It can see through walls without taking off tiles and plaster
What is an IR Thermal Camera?
An IR (infrared) thermal camera (also called a thermal imager) is a device that detects infrared radiation (heat) emitted by objects and converts it into a visible image called a thermogram. In this image:
- Warmer areas appear as red, orange, or yellow.
- Cooler areas appear as blue, purple, or black.
Unlike regular cameras, thermal cameras don’t need visible light — they work in total darkness and can “see” temperature differences as small as 0.05°C (0.09°F).
How Does Water Ingress Show Up on a Thermal Camera?
Water inside a building envelope changes the thermal properties of materials. Key principles:
- Evaporative cooling – Wet areas are cooler than dry areas because evaporating water removes heat.
- Thermal mass differences – Water has a high heat capacity; wet insulation or wood takes longer to warm up or cool down than dry material.
- Reduced insulation – Wet insulation conducts heat faster, creating cold spots in winter or warm spots in summer.
So, a thermal camera reveals anomalous temperature patterns – usually cold spots on an interior wall/ceiling (in cool weather) or warm spots (in hot weather) – that indicate hidden moisture.
Step-by-Step: Using a Thermal Camera to Find Water Ingress
1. Create a Temperature Difference (ΔT)
The method relies on a temperature contrast between wet and dry areas. Common techniques:
- Natural ΔT – Inspect on a cold morning after overnight heating, or on a sunny afternoon when exterior walls are warm.
- Forced ΔT – Use a heat gun, space heater, or even run warm water through pipes to create temporary temperature differences.
2. Scan the Building Internally and Externally
- Interior scan – Look for irregular cool patches (e.g., on ceilings below roofs, around windows, along baseboards).
- Exterior scan – Look for warmer patches where trapped moisture is releasing heat (only under certain conditions).
3. Identify Suspicious Patterns
Common water ingress signatures:
- Cold streaks from roof leaks tracing down inside a wall.
- Cool rectangles where insulation is wet and not performing.
- Linear cool areas along pipe routes (leaking pipe) or around window frames.
- Cold bands at floor-wall junctions (rising damp).
4. Confirm with a Moisture Meter
Thermal cameras are non-destructive and fast, but they show thermal anomalies, not direct proof of water. Always follow up with a pin-type or pinless moisture meter to confirm actual moisture content.
Practical Example
Scenario: A homeowner sees a ceiling stain but suspects more widespread hidden moisture.
- Evening inspection (10°C outside, 21°C inside) – Technician scans the ceiling with a thermal camera.
- Thermal image – Large irregular blue (cool) area extends beyond the visible stain, plus a cool line tracing down the wall.
- Interpretation – Water from a roof leak has spread across ceiling gypsum and is tracking down the wall cavity.
- Confirmation – Moisture meter shows elevated readings in the cool areas.
- Outcome – Repair is targeted to the actual leak source and affected area, not just the stain.
