Which Water Leak Detection Is Best?

Your roof is a serious and critical investment. For many businesses, a substantial or unnoticed roof leak could be disastrous.  Even a small, undetected leak can be devastating–wreaking havoc on the internals of a building until it has progressed into costly damage such as mold, rot, and business interruption. 

Understandably, discovering leaks in the building envelope or membrane prior to extensive damage should be your first step towards tackling repairs when investigating the health of your building. Additionally, when working with a new building, it is critical to verify the quality of roofing and waterproofing assemblies from the start.

There is more than one way to go about this process: flood testing, electronic leak detection (ELD), and thermal imaging are some of the most popular options. However, not every test method provides the same level of results.

How Flood Testing for Leak Detection Works:

Flood testing is one of the oldest methods in the book for testing horizontal waterproofing installations–but it is not intended for detecting leaks in your roof. Essentially, a controlled amount of water is added to a sealed section of the membrane to determine if that portion is watertight. The test can last anywhere from 24 to 48 hours and must be observable from below.

Flood testing works well on flat roofs and waterproofing but is difficult on a code-compliant 1/4:12 or greater slope because the water can become too deep and require the installation of temporary dams to keep the water at the proper depth. This adds to the cost and potentially damages the membrane, which is counterproductive to our goal of a leak-free membrane. Although flood testing of the drains is still a good idea. 

The complications surrounding flood testing are so numerous that the National Roofing Contractors Association (NRCA) does not recommend flood testing be used to determine the water-tightness of new roofing. Fortunately, newer methods have been developed to pick up the slack.

How Thermal Imaging (Infrared) Leak Detection Works:

Thermal leak detection relies upon infrared imaging of the subtle changes in temperature between a surface that contains moisture and one which has not. It requires the operator to use visual analysis of these thermal shifts to identify patterns in structures where moisture has invaded the building envelope.

An infrared survey report provides documentation of thermal patterns detected in the roofing system. It incorporates a subjective evaluation to aid in prioritizing repairs. An inspection is typically performed after sunset to allow the roof to cool. Areas of elevated moisture have a greater thermal mass and absorb and store larger amounts of heat than dry building materials. As the building cools, damp areas remain warm longer and will show up comparatively warmer than the surrounding dry areas in thermal images. Wet areas may as well be lit up by a neon sign to the IR Camera.

Beyond requiring a high-resolution camera with fine thermal sensitivity, leak detection using thermal imaging also requires a specialist with thermography training. While thermal imaging can detect changes in temperature that may indicate the presence of water, the visual analysis must also then be confirmed with moisture meters and/or core cuts.

Like flood testing above, infrared testing is limited in that it can only detect leaks after moisture has already penetrate the building envelope–and  not ideal for a newly installed roof. This is where electronic leak detection steps in.

Why Electronic Leak Detection (ELD) Works Best on many roofs: 

Rather than allowing water to penetrate your membrane at all, electronic leak detection protects your building from the start by ensuring your new roof is ready to weather years of service.

Rather than suffering through the costly trial-and-error methods provided by flood testing–or “putting out fires” you find through thermal detection–electronic leak detection gives you peace of mind without the need for invasive repairs. Plus, ELD methods leverage the natural conductivity of your roofing materials to detect leaks quickly.

While the two primary forms of ELD (low-voltage and high-voltage detection) are both safe and non-damaging, we prefer to utilize high-voltage detection methods following ASTM D7877 Electronic Leak Detection (ELD) Testing guidelines. The advantages of high-voltage detection over the competition are many:

• High-voltage electronic leak detection can be used on both vertical and horizontal waterproofing solutions

• Detected breaches using high-voltage methods don’t require immediate isolation during discovery

• Breaches smaller than the eye can perceive can be detected using high-voltage ELD methods

• High-voltage ELD can be used on dry surfaces, without the need to wet the membrane for detection.

While ELD methods won’t work for every membrane or deck type–the versatility provided by ELD makes it a safe and cost-effective choice for ensuring the health of your building for years to come.