How is the Weld Strength of TPO Tested?

By Thomas J Taylor PhD 01-28-2016
QUICK SHARE
Tag Icon

One of the selling points of heat-weldable single-ply membranes is that the final result is a single welded sheet of membrane covering the roof. There are no adhesive seams to pop loose and a properly welded area is often said to be twice as strong as the rest of the membrane since it's twice as thick. This all sounds good, but how does the manufacturer test weld strength? Here is a look at what we do at GAF.

The first step is to weld some TPO with the same equipment and settings that are used on a roof. In fact, we make many welds at varying speeds and temperatures to cover most conditions.

welder

We recommend roofers do a test weld at the start of each day, after lunch, and whenever conditions have changed. The strips are then cut and pulled to check quality. Here's a cross section of what a weld cut actually looks like:

At GAF, we do the exact same thing. However, instead of doing a manual pull, we use some sophisticated test equipment, which enables us to measure the actual strength. (We use a physical property tester made by Instron.) The sample gets mounted between two steel jaws and pulled as shown here:

The machine records the force needed to make the pull. If you look at the center picture, you can see that the cap layer has just broken. After that, the cap peels away from the core, as can be seen in the right-hand picture. If the weld itself opens up, then it's a bad weld. The picture on the right shows what we call a film tearing bond. We've torn the cap or core film right off the membrane, exposing the reinforcement fabric, also known as scrim.

Our tester reports the force as a graph that looks like this:

This shows that it took a peak force of around 48 pound-force to break the cap or core. Then, to peel the cap from the core, it took around 20 pound-force. These are strong numbers that demonstrate the strength our sheets.

At GAF, we quality test our membrane this way. This ensures that the product welds and is the same strength day after day, mile after membrane mile!

Learn more about TPO and which brands perform best at www.tporesults.com and watch our how-to video on hand welding.

Don't miss another GAF RoofViews post!
LATEST UPDATES
A shingle starter strip is an important part of a residential roofing system. It plays a critical role in reducing the risk of shingle blow-off along the eaves and rakes of the roof. It provides a base under the shingle at the eaves, helping the roof shed water efficiently. As its name implies, every asphalt shingle roof will start with this shingle.
A low-slope commercial roofing system is responsible for keeping the elements out of the building. During times of heavy rain, water with nowhere else to go may pond on the roof. A roof drain prevents water from ponding by providing a way for it to leave the roof.
Growing up in the northeast, tornadoes were these random events that occurred in the movies, and far off places like Kansas. But according to the National Institute of Standards and Technology (NIST), roughly 1,200 tornadoes occur in the US each year! AND they occur in all 50 states, but primarily in the lower 48 and east of the Rocky Mountains. Given that tornadoes kill more people per year in the U.S. than hurricanes and earthquakes combined, ASCE's Structural Engineering Institute revised the ASCE 7 Standard for Minimum Design Loads and Associated Criteria for Buildings and Other Structures in hopes that it will be adopted into the 2024 International Building Code.
If you're a homeowner researching new roofing options, you may be seeing a lot of information on architectural shingles as a popular choice for roof replacements. So, what are architectural shingles? Let's dive in to learn all about architectural shingles and why they are growing in popularity.
You work hard to keep that roof over your head. That's why it's important to maintain your home's longevity. Paying attention to the seasonal weather changes that affect your home will save you a significant amount of time and money. And, while you may initially think of the harshest of conditions mother nature throws our way (i.e. hurricanes, tornados, blizzards, etc.), it takes far less to cause deterioration of a home's structure over time. Luckily, an ounce of prevention is worth a pound of cure. Listed below are damaging weather conditions that arise year-round, and simple ways you (or a service professional) can protect your home.
Enjoying the beauty of winter storms—but worried about the damage it can do to your roof? By taking a few steps before and after a storm, you can protect your home and roof from icy flurries and enjoy a cozy space inside.
This blog contains information created by a variety of sources, including internal and third party writers. The opinions and views expressed do not necessarily represent those of GAF. The content is for informational purposes only. It is not intended to constitute financial, accounting, tax or legal advice. GAF does not guarantee the accuracy, reliability, and completeness of the information. In no event shall GAF be held responsible or liable for errors or omissions in the content or for the results, damages or losses caused by or in connection with the use of or reliance on the content.

Interested in sharing or republishing our content? We kindly ask you to adhere to our guidelines.