spray foam over roofs with pipes, vents, and HVAC units

Can Spray Foam Be Installed If Vents and HVAC Equipment Are on the Roof?

So, you have a commercial building with a pretty busy roof.

Your roof has vents, pipes, skylights, HVAC units, and maybe some other boxes you don’t know what they do.

And…you’ve read about the benefits of a spray foam roof, and you think “this could be a great solution to our roofing problems”.

But you wonder if a spray foam roof can be installed on a busy roof.

If you’re looking for a quick answer:

Spray foam roofs CAN be installed on roofs with vents and HVAC equipment. The “busier” the roof, the more beneficial the spray foam roof will be versus traditional roofing systems. This is because spray foam is fluid-applied, which is easy to install (reduces installation time) and self-adheres directly to the penetration (provides a seamless water barrier).

If you’d like more details, please read below.

In this article, you’ll learn:

  • How is spray foam installed on a roof?
  • How does spray foam get installed around vents and HVAC equipment?
  • How does spray foam reduce the installation time versus other roofing systems?
  • Why is a seamless water barrier better than a non-seamless water barrier?

And just so you’re aware, we only write articles based on true events and experiences. Every piece of content written at West Roofing Systems is produced in-house. Every article is reviewed and edited by a roofer/salesman with more than 30+ years of experience in the field.

West Roofing Systems has been in commercial roofing since 1979.

How is spray foam installed on a roof?

Do spray foam contractors use jetpacks?

That would be super cool, but they do not.

It’s not too far off though.

Spray foam is created through the combination of two chemicals. These chemicals, called an “A-side” and a “B-side” are stored in 55-gallon drums.

The drums are stored in a box truck that’s parked near the building.

The chemicals are pumped through a machine and then through a hose, where they meet at the tip of a spray gun.

When the trigger is squeezed, a liquid is released.

That liquid increases 30x its size within a few seconds. This is the spray polyurethane foam product.

Here’s a video of spray foam being installed:

NOTE: A major difference between spray foam roofs and traditional roofing systems such as Metal, Single-Ply, and Built-Up roofs is that spray foam is fluid-applied. Other roofing systems use panels or rolled-out materials that are time-consuming to fit around penetrations.

How does spray foam get installed around vents and HVAC equipment?

I wanted to note that during installation, all vents and HVAC units are wrapped. This is to prevent spray foam materials from entering the building through the units.

As far as installation, the spray foam is installed around the penetrations, making them a part of the seamless roofing system.

You can see in the photo below how the HVAC curb becomes a part of the roof:

spray foam roof around an HVAC curb

How does spray foam reduce the installation time versus other roofing systems?

Since spray foam is fluid-applied, instead of rolled, it can be installed around penetrations very easily.

Where it might take a roofer installing a traditional roofing system 30 minutes to flash around a curb, spray foam can be installed in about two minutes.

Watch this video here, where it shows how easily spray foam is installed around a curb:

Since vents, HVAC equipment, and curbs get in the way of a roofing system that’s rolled out, they need to cut and custom fit the roof around these penetrations.

Installing a roofing system around a penetration is difficult. Custom cutting, termination metal, and adhesives might have to be used to install a single-ply roofing system.

Hopefully, you can see that the more HVAC units, vents, pipes, etc. that a roof has, the faster the roof can be installed with spray foam as opposed to other roofing systems.

NOTE: If your roof doesn’t have many penetrations, other roofing systems can be installed faster than spray foam.

Why is a seamless water barrier better than a non-seamless water barrier?

Spray foam fully encapsulates all penetrations, creating a seamless water barrier.

See how spray foam fully adheres to the curb? This creates a seamless water barrier.

spray foam roof around a curb

Here’s another photo of a pipe/vent on a spray foam roof. See how the pipe becomes a part of the field of the roof?

spray foam roof around a pipe or vent

Here is a TPO roof installed around an HVAC unit. Since the HVAC unit is in the way, the membrane must be cut.

This is different than traditional roofing systems, where boots, adhesives, sealants, and termination metal are used:

Here is a TPO roof installed around an HVAC unit. Since the HVAC unit is in the way, the membrane must be cut.

An adhesive and termination bar is used to make the TPO membrane watertight right up to the unit.

Source: https://www.youtube.com/watch?v=IEC3c-fHVl0

You might ask, so if they are both watertight, then what’s the difference?

The difference is that spray foam makes the penetration a part of the roof, which doesn’t have any seams or sealants.

Traditional roofing systems rely on seams and sealants to make the penetration watertight.

We aren’t saying that it’s bad to have seams and sealants, but it’s just not as good as encapsulating the area.

When a roof expands and contracts with weather fluctuations, stress is created at the seams.

NOTE: Any roofing system can work great. It’s the professionalism of the installation that matters most.

What are your next steps?

Now that you know that spray polyurethane foam is fluid-applied that can be installed around vents and HVAC units, what should you do now?

Most building owners have these questions:

West Roofing Systems has been in commercial roofing since 1979. We go all over the U.S. installing spray foam and roof coating systems. We love the challenge of your walking your unique roofing situation, diagnosing what’s wrong, and giving you several options for repair.

If you’d like to learn more about spray foam roofing, please download our cheat sheet below.

The spray foam roofing cheat sheet - download now

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