I left a datalogger close to a mouldy wall for two weeks. The tenant sent back data this morning.

Laser thermometer

Use a laser thermometer to set up your insulation and heating system.
Identify areas vulnerable to mould and condensation.


  1. Laser thermometers cost £10 – £20, are very accurate and help an owner and occupier of a property understand and visualise heat loss.
  2. Use ice and boiling water to check the calibration.
  3. Use a laser thermometer for measuring and balancing the distribution of heat across a property.
  4. Turn down valves on radiators so that heat is evenly distributed across a property.
  5. Balance insulation, such as by redistributing loft insulation.
  6. Identify cold spots and keep dry warm circulating across vulnerable areas.
  7. Consider drawing image with the laser thermometer or using a thermal imaging camera for visualising isotherms – cold spots.
  8. Note it is difficult to identify cold spots unless it is cold outside and warm inside.
  9. Metal, such as from RSJs are the single greatest risk to interstitial condensation.

Surveyor uses include:

  1. Measure radiators with boiler on, and nearby walls to determine the balance of heat.
  2. Measure the temperature of a datalogger and damp to work out the off-set.
  3. Laser thermometers can be use to calculate the surface relative humidity: mouldpoint.co.uk
  4. Laser thermometers use to identify areas at risk of condensation or mould.
  5. Identify thermal bridges.

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