How do you Use a
Thermal Camera
for Roof Inspections?

HOW DO YOU USE A THERMAL CAMERA FOR ROOF INSPECTIONS?

Safety

If you’re a homeowner wanting to DIY your roof, putting safety first is paramount. If something happens no one will be around to help

It’s important then that you take extra caution when going up the roof. Risky areas like roof edges shouldn't be toyed with. In this regard, it’s best to observe all local approaches and corresponding tie-off requirements.

Also, this means not going up without a qualified escort. A helping hand can go a long way in getting you back safe.

IMPORTANT ADVISORY:

Bear in mind that you will have to “GO SLOW” when working with a thermal camera on the roof at night. Your eyes need time to adjust to the cam’s view screen as you are made momentarily “night blind” when viewing things from the LCD screen.

Thus, a pre-inspection daylight walk around the roof should be in order. Such should help you identify possible hazards while giving you a rough feel of what it's like working several feet above ground.  

Timing is everything!

For best results, it’s best to observe proper timing to conduct your thermal surveys. Thermal energy of the roof and any part of it is a transient matter - affected primarily by the sun and to lesser degree by its surroundings.

For low-slope roofs, summer is one of the best times to conduct a roof survey. That’s because there’s a lot of sun on these days. Making it a lot easier to let problematic areas stand out.

This is where doing the inspection an hour or two after sunset will come in handy. At this point, the roof should have cooled making the wet and dry insulations distinctively clear, due to their temperature differences. Wet insulation should be warmer making it easily identifiable.

Make sure the night is not so breezy - free of strong winds which could affect the cooling temperature of the roof. Finding the optimum weather conditions is therefore necessary to produce best thermal imaging results.

Bear in mind that technically the following four weather-related factors can make or break the integrity of your thermal readings:

Wind speed

Degree of solar loading made

Rate of temperature change (hours before the actual viewing)

The difference between the interior and the exterior temperatures (of the abode)

In general, these conditions allow for the best thermography results:

Sunny/clear weather conditions a day prior to the inspections

Winds not more than 15 mph

A drastic decrease in the home’s ambient temperature an hour or two before thermal images are collected

To be able to conduct a thorough thermal survey, the insides of your home or of any building should be at least 10°C or 18°F warmer inside than outside. Then, it goes without saying that doing a roof moisture survey in daylight is problematic right from the onset.

MATERIAL MATTERS

Being aware of the material being examined under your thermal camera’s auspices is wise. Each material has a different ability to absorb and reflect heat. This means solar loading will have a distinct effect on each and every material roofing composition.

In this regard, knowing what particular roofing insulation is used is wise. Further, you should be able to distinguish how many layers of insulation is used to make your thermal roof inspection more accurate.

This way, it would be easier for you to know the location of the leaks zeroing in on these areas in time.

Normally, a BUR or built-up roof (which usually is the case) with “bald” single-ply membrane, the prospects of using a thermography to expose moisture decay should be well and good.

As a roofer or a DIY homeowner your ultimate goal is to expose areas where moisture decay is present. You should be able to do this in one or two proven ways where the presence of wet insulation becomes apparent , thanks to the greater thermal conductivity or higher heat capacitance.

To note, you might find your thermal roof moisture survey in an uphill climb when dealing with ballasted single-ply roofs. Same goes through with newer roofing structures which utilize low-absorbency insulations.  

MARK IT UP

You could have a spray paint ready when doing the thermal inspection. That way, you would be able to mark directly wet areas identified by your infrared cam. Numbering these areas would be a great way of reference making it easier for you to plan your next step of action.

Marking makes it easier for you to factor needed repairs when daylight comes. Then, you can make the most of a core sampler or a moisture probe to further confirm your thermal findings.

You need not worry about finding the actual leak when doing the thermal inspection. As its general location is known, getting to its exact location should be a walk in the park in broad daylight.