Two thermal scans of the same house on different days can look completely different. That’s not the camera being wrong — it’s the conditions. Knowing what affects a scan helps you understand the results.
What are the best conditions for a thermal imaging scan?
Thermal imaging works best with a large, steady temperature difference between inside and outside — BRANZ research cites around 10°C for several hours — no direct sun on the surfaces for a few hours beforehand, low wind and dry surfaces. Early morning or after sunset is often best. For damp after a leak, evaporation also helps.
The conditions that matter
| Factor | Why it matters | What helps |
|---|---|---|
| Temperature difference | Heat flow reveals insulation gaps and some damp | Heating on inside on a cool day; BRANZ cites about 10°C for insulation work |
| Sun | Sun heats surfaces and masks patterns | No direct sun for some hours beforehand; scan early or late |
| Wind | Cools outside surfaces unevenly | Calm days for exterior scans |
| Rain / wet surfaces | Wet outside surfaces confuse readings | Dry surfaces for exterior scans |
| Reflective surfaces | Tiles, glass, gloss paint reflect heat | Change angle; know what’s reflective |
| Recent activity | Showers, cooking, heaters, furniture against walls | Note what’s been used |
These come from BRANZ study report SR232 on thermal imaging of wall insulation, which summarises international thermography guidance.
Leak and damp scans vs insulation scans
- Insulation scans rely on heat flowing through the wall, so they need the temperature difference.
- Damp scans after a leak often rely on evaporation cooling wet surfaces. They can work in a wider range of conditions, but results still vary and need confirming with a moisture meter.
Why results vary
- Morning sun on an east wall can hide a damp patch
- A heater can make one wall warmer than others
- Furniture against a wall changes its temperature
- Draughts can mimic damp
That’s why a trained eye and a moisture meter matter more than the picture.
Tips if you’re having a scan done
- Tell the technician what happened and when.
- Avoid running heaters directly at the affected wall right before.
- Move furniture off affected walls if you can.
- Ask what the results mean — and what they don’t.
Our check
When you hire our Drying Combo, our technician delivers the equipment and, where suitable, does a free on-site thermal imaging and moisture check. We scan affected areas and confirm with a moisture meter. See what thermal imaging can and can’t detect.
| Drying Combo | What you get |
|---|---|
| Equipment | Commercial 90 L dehumidifier + two drying fans |
| Testing | Free on-site thermal image assessment and moisture test, included where suitable |
| Delivery | Our technician delivers the equipment and does the testing on site; Auckland delivery and pick-up, subject to booking timing and site access |
| Price | $75 + GST per day (3-day minimum) or $400 + GST for 7 days |
See the full offer: free thermal imaging and moisture testing with the Drying Combo.
What thermal imaging and moisture testing can’t do
We’d rather be upfront:
- Thermal imaging indicates, it doesn’t prove. The camera reads surface temperature. A cool patch can be damp, but it can also be a draught, missing insulation, a cold-water pipe or shade from the morning sun. Our technician checks suspicious areas with a moisture meter on site before treating them as wet.
- Meters read accessible spots. A moisture meter gives a reading where it touches. It can’t see right through a sealed cavity, and we don’t cut open walls.
- It isn’t a plumbing repair. We can help show where water has spread. Finding and fixing a failed pipe, shower tray or fitting is a job for a licensed plumber.
- We’re drying specialists, not plumbers or inspectors. We aren’t a licensed plumber, a pre-purchase building inspector or an acoustic/tracer-gas leak detection specialist, and we’ll tell you when you need one.
- It isn’t a building report. This check supports your drying setup. It isn’t a pre-purchase inspection, a weathertightness report or a code compliance document. For roof, cladding or structural concerns, talk to a qualified building surveyor or inspector.
Frequently asked questions
What temperature difference is needed for thermal imaging?
For insulation work, BRANZ research cites a minimum of around 10°C between inside and outside, held for several hours.
Can thermal imaging be done in summer?
Yes, but results can be harder to interpret because of sun and smaller temperature differences. Damp scans after a leak can still be useful when confirmed with a moisture meter.
Why scan early morning or at night?
To avoid the effect of sun heating surfaces, which can mask temperature patterns.
Does wind affect thermal imaging?
Yes. Wind cools outside surfaces unevenly and can confuse exterior scans.
Is the scan included with drying hire?
Where suitable, our technician does a free on-site thermal imaging and moisture check when you hire the Dry Me Now Drying Combo.
Book the Drying Combo with a free moisture check
If you’ve had a leak, overflow or flood in Auckland, call Dry Me Now on 021 877 504 or use the enquiry form on our thermal imaging and moisture testing page. Tell us what happened and which rooms are affected, and we’ll confirm availability and delivery. Our technician delivers the machines and does the testing on site.