Roof Thermography: Advanced Solution for Moisture Problems

With roof thermography, thermal imaging cameras create detailed maps of low-slope roofs, showing where excess moisture is trapped, where the source of a leak may be, or where there is soaked or compromised insulation.

When you hear the word ‘thermal imaging,’ what’s the first thing that comes to mind? 

👉 Army surveillance? 

👉 Alien vs. Predator? 

Thermal imaging is actually a powerful technology with benefits that aren’t limited to military maneuvers or bad action movies. In recent years, multiple industries have benefited from thermal imaging: facilities maintenance, construction, and especially roofing. 

In the roofing industry in particular, the infrared can detect the presence of wet insulation on flat roofs, making it easier to detect leaks before they damage a roof beyond repair. There’s even a term for it: roof thermography.

This early warning system can save you a lot of money on roof replacement because only certain sections need to be removed and repaired instead of the entire structure. Even more important, it can protect workers from injury and even death by highlighting deteriorated areas that might not support their weight. 

At Stybek Roofing, we’ve always valued two outcomes: a quality roof and safe working environment. With roof thermography, you get the best of both worlds.

Why is Roof Thermography Important?

For more than 30 years, infrared imaging has been used to detect moisture within flat or low-slope roofing systems. By graphically documenting the extent and location of subsurface moisture within a roof, thermography can provide valuable insight into its condition.

roof thermography
The red lines in this thermography image indicate significant areas of thermal bridging. The greenish-yellow areas indicate wet substrate material such as insulation and cover board.

Thermal imaging delivers multiple benefits for roof owners, some of which are highlighted below.

Exposes Safety Issues

When moisture accumulates in your roof’s system, the deck becomes rotted or rusty, compromising its structural integrity. This can pose a serious safety hazard to workers doing repairs, HVAC inspections, and other duties that require them to be on the roof. Approximately 42,000 Canadian workers are injured in fall accidents every year, many of them due to dangerous working conditions.

Over time, dampness can lead to health issues like mold, which puts your employees at risk. Exposure to mold spores may trigger allergic symptoms including coughing, difficulty breathing, fatigue, itching, runny nose, sneezing, and wheezing. A person’s sensitivity to mold can increase with repeated exposure, resulting in more severe allergic reactions.

Prevents Interior Damage

Having water intrusion in your roof system can also cause interior damage from leaks, which can impact your building’s electrical and mechanical systems. With some businesses, inventory damage can result. It all adds up to thousands, even millions of dollars worth of lost profits.

Cost Savings With Roof Thermography

Roof replacement is expensive. By using roof thermography, you can identify moisture damage and take measures while it’s still easier to fix. This may include removal of damaged sections or measures like wet insulation remediation: when roof insulation is wet, it conducts thermal energy more effectively, which raises your building’s heating and cooling costs

How Roof Thermography Works

Thermal imaging systems are designed to detect heat trapped by moisture within a roofing system. This condition creates a difference in radiant heat loss once heat gain stops. Since it takes longer for this moisture to cool than the rest of the roof system, infrared imagers can detect it.

Imaging is only effective, however, when there is an insulating deck or the insulation is sandwiched between the roof deck and the waterproofing membrane. In both cases, the insulation must be in continuous contact with the membrane underside, or the results will be unreliable.

With an infrared imager, you can monitor the heat emitted from your roof surface and surrounding equipment in real time. This is similar to how video cameras instantaneously capture visible light. Infrared imagers detect heat patterns across surfaces by converting infrared heat into visible light.

Thermography can be applied to both single-ply and built-up roofing systems. The roof membrane can be clear or gravel-covered as long as the gravel is pea-sized or smaller. It is also possible to use thermal imaging on coated and uncoated spray-applied polyurethane roofing.

Thermal roof scanning uses vivid colours to highlight areas where moisture has collected.
The orange and yellow colours in the above picture are indicating significant wet areas of substrate.

Conditions Necessary For A Successful Thermal Roof Scan

With roof thermography, certain conditions need to be in place for best results. If they aren’t, it can invalidate the scan. Below is an overview of best practices for both warm and cold weather scanning.

Warm Weather Scans

With warm weather scanning, you can measure the temperature difference between wet and dry roof insulation. This type of roof moisture survey is conducted after the sun has set during warm weather. Sunlight heats the roof and wet insulation during the summer. During the evening, when the sun has set and the dry portions of the roof have cooled, these wet areas will retain heat and appear as hot spots on thermal imaging equipment.

Cold Weather Scans

Cold weather scans are conducted throughout the year during cold weather or early in the morning. This survey measures the difference between the temperature inside and outside. Due to its higher thermal conductivity, wet roof insulation will transfer more heat out of a building when the inside is warmer than the outside.

Using Moisture Metres

You can also use a moisture metre in conjunction with thermal imaging to confirm whether there is moisture present. A thermal imager alone cannot prove moisture exists on a roof; it can only indicate where the signature of the roof surface suggests moisture may exist. A certified technician must still verify and locate the exact location of the area. 

There are two types of moisture metre: penetrating and non-penetrating.

  • A penetration moisture metre measures moisture content by probing into the roof surface. These metres are more accurate in some cases than non-penetrating ones, but they penetrate the roof surface, so repair work is required afterwards.
  • A non-penetrating moisture metre does not penetrate the roof surface and cause damage. Instead, sensors in the system measure moisture levels. While not always as accurate as penetrating moisture metres, they are still useful for verifying the presence of moisture without penetrating the roof.

How to Conduct an Inspection Using Roof Thermography

For most locations in Ontario, you’ll want to perform roof thermography after the sun sets following a clear day. An hour or two after sunset is a good time to begin the inspection if the night is clear and windless and the rooftop surface is dry. During this condition, the wet and dry insulation are at different temperatures because of thermal capacitance differences. 

Even if conditions are not ideal, you can do a roof moisture inspection at night, provided there is at least 10°C (18°F) difference between the indoor and outdoor temperatures in the building. In these conditions, heat will transfer through the wet insulation at a greater rate, causing these areas to appear warmer than the dry roof. 

To ensure complete coverage of the roof, maneuver the thermal imager across the roof in a systematic manner. The most common method of performing ground-based infrared inspections is to use a handheld thermal imager to view the top surface of the subject roof(s). In addition, thermal imagers can be operated from manned aircraft, such as helicopters or airplanes, as well as unmanned aerial systems like drones.

Detecting wet insulation is easier because it is warmer than dry insulation, but depending on the type of roof, the exact pattern will vary. In addition, it is important to know what kind of insulation is used and how many layers there are and to pay special attention to those areas when conducting the survey.

As you examine the roof, mark out possible wet areas on the surface using spray paint and numbering each section for future reference. If the owner has given permission for an invasive test, you can confirm the presence of moisture  with a moisture probe or core sampler if necessary. Just make sure the destructive test locations are properly repaired afterward.

Regardless of the situation, you’ll be working on the roof, so safety is paramount. This means:

  • Doing a preliminary walk-around during the day to do a visual inspection and identify potential hazards.
  • When working near the edge of the roof, observe all local tie-off and approach requirements to prevent a fall. 
  • Going slowly while working at night, as your eyes will adjust to the imager’s LCD screen and you can become temporarily night-blind.

Aerial Versus Ground-Based Inspections

With the advancement of technology, several types of lightweight drones can now be equipped with thermal imaging sensors, allowing millions of square feet of roofing to be inspected in a single evening.

Aerial inspections offer rapid data collection, but they are more likely to miss small anomalies. Only a walkover inspection allows correlation of thermal data with roof conditions. Because real-time verification is available during an infrared inspection, you can mark only moisture-damaged areas, saving time and avoiding the need for a return visit.

Are There Limitations With Roof Thermography? 

Roof thermography is a powerful technology, but it has some limitations under certain circumstances. For example:

  • Lack of solar load, high winds, and heavy dew make detecting thermal patterns on roofs difficult. 
  • Thermal imaging is not suitable for heavily ballasted roofs or roofs with more than one layer of insulation.
  • Thermal imaging is typically not used to inspect inverted membrane roofs.

Moisture metres also have limitations. A non-penetrating metre registers EPDM roof membranes as wet due to their high carbon content. Infrared can be used with EPDM, but a penetrating moisture metre must be used to confirm moisture levels. 

To overcome these challenges and ensure you get the information needed, retain a qualified and experienced roofing specialist to carry out your roof thermography scan and moisture detection.

What Are Roof Thermographer Qualifications?

Using infrared technology to inspect roofs is both an art and a science. Thermal imaging has become more affordable and user-friendly in recent years, but thermography is not a ‘point-and-shoot’ technology like photography or videography. A thermographer’s knowledge and skill level greatly influence the accuracy of an infrared inspection. For this reason, you should only retain experienced thermographers who understand building performance and roofing systems to conduct infrared inspections of your property.

Preventative Maintenance Can Extend the Life of Your Commercial Roof

In low-rise buildings like industrial buildings and retail buildings, the roofing system is the most expensive component that will need to be replaced over time. Moisture intrusion is one of the major factors affecting the durability and performance of roof systems. When they start failing and developing leaks, it can increase energy consumption and costs, compromise the structural integrity of the building and even worse, present a health and safety risk to occupants.

The problem is that building owners and occupants usually aren’t aware of a roof moisture problem until they notice a leak on the inside. By that point, it’s a given that the roofing membrane and insulation are already saturated by water. Visual inspections alone can’t always detect water damage before the ceiling develops a leak, and finding the exact source is often difficult, since water can move along the roof deck before existing and dripping onto the ceiling.

Roof thermography carried out by a trained professional can provide the visual insights needed to detect the source and extent of the problem, so that it can be fixed before the entire structure is compromised. With roofing systems that can’t be scanned, such as inverted roof membrane assemblies (where the thermal insulation covers the membrane), a commercial roofing specialist can recommend other ways to identify and fix problems.

Hire Stybek for Your Commercial Roofing Needs

At Stybek Roofing, we support the business owners who provide jobs and economic security to their communities by helping ensure the integrity of their workplaces. By assessing your roof system and identifying water intrusions before major structural damage occurs, our roof inspection services can:

  • Keep your employees and tenants safer
  • Protect your investment in the building 
  • Reduce your annual repair budget

When you work with us, you can count on professional and caring services from professionals who know how to use state-of-the-art diagnostics like roof thermography. Whether you need help with routine maintenance or a sudden emergency, Stybek is there when and where you need us. To learn more, give us a call at (519) 888-9676. 

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