Home Garden

How to Meter a Roof

Metering your roof to monitor for potential leaks that could lead to mold growth (or worse) is a quick and easy way to be proactive about your home's health. There are two methods for metering your roof. The one you should use is dependent on the access you have to your roof joists and the budget you have to work with.

Things You'll Need

  • Moisture meter
  • Thermal imaging camera
  • Surface thermometer
Show More


  1. Moisture Meter

    • 1

      Obtain a moisture meter from a local hardware or home improvement store. There are pin and nonpin versions. The pin versions will only work with materials soft enough for the pins to penetrate (wood, carpet, drywall, etc).

    • 2

      Turn the unit on and wait thirty seconds to two minutes for it to calibrate. Instructions for calibration will be included with the unit.

    • 3

      Press the sensor pins (or detection surface if you're using a nonpin unit) into the roof joists in various locations and take moisture readings. If the moisture level reads above five percent, there's a chance for the joist to bow and cause structural damage to the roof.

    • 4

      Identify the source of any intrusive moisture by tracking upward from the point where moisture was first detected.

    Thermal Imager

    • 5

      Obtain a thermal imaging camera from a local rental company.

    • 6

      Turn on the thermal imaging camera and calibrate it by taking the temperature of a nearby wall with a surface thermometer and adjusting the thermal imager to match the reading.

    • 7

      Point the thermal imager at the roof joists. Areas that are lower in temperature (usually blue or green on the thermal imager screen) are likely to either be poorly insulated or suffering from water leakage. The thermal imager is far faster than a moisture meter and the source of leaks can be easily identified by the color patterns on the thermal imaging screen.