Here’s a riddle: what do a sheet of paper and a rock have in common? Aside from being equally deadly weapons in a particular zero-sum hand game, the scientific answer is that they both grow and shrink when the temperature changes around them. The phenomenon is called thermal expansion and contraction, and it plays a key role in the success (or failure) of many outdoor construction projects.
How it Works
When you heat an object up, its particles begin to move and spread out. As they spread, the object becomes bigger. This is called thermal expansion, and it happens to everything — from water to wood to metal piping. The opposite effect, thermal contraction, happens when temperatures decrease. Because cooling reduces kinetic energy, an object will shrink as the molecules slow down.
Engineers measure thermal expansion and contraction in building materials with a ratio called the coefficient of expansion. This ratio is the comparison of an object’s change in size with its change in temperature, and it varies by material. For instance, a copper rod will expand more than a cast iron rod. Polycarbonates will expand and contract even less, which is why it is a popular building material among more scientifically-conscious companies.
Though thermal expansion and contraction happens at a molecular level, there’s nothing small about the outcome.
For instance, imagine a location where temperatures fall 20 degrees Fahrenheit at night — a typical change regardless of climate. With just this 20-degree shift over the course of a day, cast iron, carbon, and alloy steel pipes will increase in volume by an eighth of an inch. Stainless steel, copper, and monel pipes will expand nearly a quarter of an inch in that same time. With the combined movement from both expansion and contraction, that’s over 15 inches of movement for such a pipe each month.
Now, add in the fact that rooftop wind and precipitation conditions are more intense than those on the ground, with rooftop temperatures in some areas swelling to 200 degrees on a summer day. You can imagine how these conditions might damage the integrity of the pipes, support systems, and surrounding rooftop areas over the course of months or years.
Can You Take the Heat?
You can’t change physics, but you can mitigate its effects. The solution is to use dynamic support systems for rooftop piping projects. These meticulously engineered systems respond to the natural expansion and contraction of metals and other materials on rooftops by spreading load and allowing room for expansion.
A roller support system, for example, absorbs the movement of the pipes through flexible components without transferring unwanted energy to the roofing envelope. These components, when crafted from the right materials for each particular usage, will ensure the longevity and durability of the support for maximum protection to the roof.
A high-quality rooftop support system for pipes should:
- Be custom-made depending on the qualities of the pipe and roof
- Protect the integrity of the rooftop and surroundings
- Meet OSHA requirements
- Have a secure but flexible support structure to allow room for expansion
Of course, there are many variables that will dictate the type of support system you implement. It’s not just the type of metal used for the pipe, but the location of the pipe — whether it’s in the shade or sun, how long it is, and whether it is a liquid, gas, or electrical line. Each scenario requires a unique approach.
Whether this is your first rooftop piping project or you’ve been using outdated supports like treated wood block, there is no better time to invest in a support system than now. With scientifically engineered structures designed by a trustworthy team, you’ll save thousands in potential damage and dramatically increases the longevity of your roof and pipes.