👁️ With the Naked Eye
If you look at this wall with the naked eye, you will notice absolutely nothing.
Detecting Insulation Defects with a Thermal Camera
Fibrous insulation materials, such as mineral wool (glass wool and rock wool), are excellent at temperature retention and sound insulation. However, because they are soft like a "duvet", they require great care during installation, especially when fitted vertically (e.g. inside a plasterboard wall).
If the fitter cuts them narrower than the stud cavity, they won't wedge tightly. If the home has moisture (and no vapour barrier was installed), the rock wool absorbs water, becomes heavy and, sooner or later, slides downward due to gravity. This phenomenon is called "slumping".
1. The 'X-Ray' of the Wall
What happens when the insulation slides? At the bottom of the wall a double, crumpled layer of rock wool piles up. But at the top of the wall (near the ceiling), a huge air void remains where there is nothing but bare plasterboard!
📸 With a Thermal Camera
If you look at it with a thermal camera on a cold winter day (with the heating on), the image is revelatory: The bottom of the wall will show warm colours (yellow, orange), proving the insulation holds the room's heat. The top will display large, dark blue or purple patches - the frozen void from which your heat escapes freely to the outside!
2. Other 'Crimes' the Camera Catches
Slumping is not the only problem thermography uncovers. The camera sees everything:
📐 Gaps in XPS/EPS Boards
In an external insulation system or roof insulation, the rigid boards must fit perfectly edge to edge. If the contractor leaves a 1-2 cm gap and doesn't fill it with PU foam (but only covers it superficially with render), the camera will show a perfect, frozen "grid" of lines on your wall!
🔧 Forgotten Spots
Very often, in hard-to-reach areas (e.g. behind rafters on the roof or around pipes), tradesmen can't be bothered to cut the material to fit the hole and simply leave it uninsulated. The camera will light up these spots like a beacon.
3. The 10x10 Model Experiment (The Loft Renovation)
We converted the loft with plasterboard and installed rock wool. The second winter, we feel cold despite the heating working.
❌ Scenario A (The Invisible Loss)
We assume "this year is just very cold". We turn up the thermostat, burn more electricity, but the upper walls still feel cold to the touch. We believe the insulation "isn't good enough".
✅ Scenario B (The Camera Inspection)
We bring the engineer. The thermal camera shows that in 3 of the 10 loft walls, the rock wool has slid down by 40 cm! We now know with millimetre accuracy. We don't need to demolish the entire loft. We carefully open 3 small holes at the top of the plasterboard, add new material to fill the void, and patch. The problem is solved at minimal cost.
The Final Conclusion: Paying for the best insulation on the market does not guarantee results if the installation is poor. Thermography is the ultimate "Quality Control Certificate" for construction. Before accepting a major renovation or insulation project, demand a thermal camera inspection!
Related Articles
Building thermography: Detecting invisible insulation problems When is the ideal season for building thermography Diagnosing moisture and mould with infrared camera The n50 directive: Limits for Passive Houses (Passivhaus)
Ventilation, Airtightness & Real Consumption: Climate Control
Return to category.
Go to categoryCentral Guide
Return to the central guide.
Go to guide