Why Do Small Rooftop Pipes Move?

How to Stop or Prevent Pipes from Moving on Low Slope and Flat Roofs.

As we all know, every step of a commercial roof installation is essential in protecting the building envelope, but one often overlooked element is properly providing long-term support for small rooftop pipes and conduit. Professional roofing contractors will understand that unsupported pipes do not remain stationary on a flat roof.  Below are some of the key factors that cause small rooftop pipes to move, and how to stop or prevent excessive movement.

What Are Small Rooftop Pipes?

Small rooftop pipes are defined as pipe or conduit that is 6-inches or less in diameter. Typically, these pipes are constructed of either polyvinyl chloride (PVC), cast iron, steel, or copper. While Small rooftop pipes can be used for a wide variety of purposes, some of the most common uses include:

• Lines that carry any type of liquid or industrial fluids
• Gas lines (non-liquid)
• Electrical wiring (including solar conduit)

In all cases, small rooftop pipes should be secured in a manner that safely accommodates the building’s expansion and contraction.

Why Do Small Rooftop Pipes Move?

There is no good reason to leave proper pipe supports out of a commercial roofing project. The cost for small rooftop pipe supports is not hugely significant as a percentage of the overall cost of the roofing system.  More important, with potentially dangerous or hazardous liquids or gas running through rooftop pipes, using the proper support system can help to minimize issues that could arise from moving or broken pipes.

Below are four common reasons why small rooftop pipes move:

Thermal Expansion and Contraction

The most common reason why rooftop pipes move is thermal expansion and contraction due to temperature changes from the weather. As buildings and roofs heat up, not only does the temperature of the pipe change, but the temperature of the contents inside the pipe also change. Either can cause the pipe to expand or contract. On a black or dark-colored roof that can heat to over 180° F, it’s easy to understand how the temperature can affect rooftop pipes.

When unsecured pipes move, they can generate forces and stresses that can be damaging, particularly at connections, bends, and elbows, not to mention the potential damage to the roofing cover or membrane that an unsupported pipe can cause.  

Severe Weather and Thawing

In addition to thermal expansion and contraction, strong winds and severe weather situations can wreak havoc on rooftop piping systems. Thunderstorms, torrential rainfall, hailstorms, and hurricanes, are often accompanied by strong winds, which can bend, or break pipes, and even lift them out of unsecured supports leaving them loose on the roof. In fact, even some engineered pipe supports can be affected by high winds, so it’s prudent for building owners to work with their roofing contractor to properly secure the pipe supports, particularly in high wind zones and coastal areas. In addition, drifting snow on the roof can push pipes around, causing damage that frequently goes un-noticed until the snow thaws or a pipe breaks

Deteriorating Wood Blocks

The most popular type of non-engineered pipe support is pressure-treated wood blocks with metal pipe straps to hold the pipes in place. While this option doesn’t penetrate the membrane and can be adapted easily according to the height and location of the pipes, wood block supports are not a great long-term performance option for supporting conduit and small rooftop pipes. Over time all wood blocks, including pressure-treated blocks, rot, splinter and deteriorate. Not only does this mean that the rooftop pipe that was originally being held is no longer secure, but it is also likely that the pipe is now freely moving around on the roof, along with the deteriorating wood and metal strapping. This scenario greatly increases the potential of damaging the roof cover.

Eliminating and Preventing Pipe Movement

Understanding that conduit and pipes can and do move around on the roof makes it more important to find a solution that stops or significantly minimizes rooftop movement.  

PipeGuard^®

When it comes to roofing pipe supports, nothing is faster or easier than OMG PipeGuard. Triangular shaped with integral pipe clamps and made from heavy-duty EPDM, PipeGuard units are designed to weather the elements while securely holding rooftop pipes in place.

PipeGuard units are available in five sizes and can accommodate ½- to 5-inch diameter pipes, tubes, and conduit. PipeGuards require no additional parts or tools for a simple and fast installation that generally takes less than three seconds per unit.

Height Adjustable and Strut Model PipeGuards

In addition to the one-piece ‘squeeze’ style PipeGuards, OMG also offers strut model configurations in  4-, 6- and 10-inch lengths to support multiple pipes up to 6-inches in diameter heights from 4- to 10-inches off the roof surface.

Custom Applications

If your project calls for a custom-designed solution, we can design and fabricate a pipe support system to accommodate your specifications and requirements. Contact us at 800.633.3800 to get started with your custom pipe support system.