Why Spray Foam Roofs Need 2 Layers of Coating

Greg PalyaSpray Polyurethane Foam Roofing

Let’s say you need some work done…say you need your car painted.

You see if any of your friends can do it…nope.

You see if anyone in your family knows a car painter…nope.

You contemplate watching 5 hours of YouTube videos, hanging up a tarp in your garage and spending money on likely one-time-use supplies…huge nope!

Your only option is to go online, call a few paint shops, and get a few quotes.

The quotes have come in, they are:

Quote #1 = $1300

Quote #2 = $1425

Quote #3 = $400


The first thing that’s probably going through your mind is…why is this quote so cheap and how bad of a job is this going to be?

A similar scenario happened to West Roofing Systems when quoting a commercial spray foam roofing job.

In fact, the low bid on the job was lower than West Roofing Systems’ cost for the materials!

Now that’s a clear indication that the work quoted for the job was not apples to apples.

So why was their quote so much cheaper than ours?

Since West Roofing Systems has been installing spray foam roofs for 40+ years and servicing hundreds of happy clients each year, we know our prices are competitive. If not, then we wouldn’t still be around.

Let’s get into a story of how and why this happened.



What happens when you have only 1 layer of coating over a spray foam roof?

Imagine instead of your car needing to be painted, you’re the building owner of a large warehouse whose spray foam roof has been performing great the past 15 years.

Your 15-year warranty is about up, so you need to recoat your roof in order to get a new warranty.

You contact a few spray foam roofing contractors (including the contractor who performed the initial work), who, after inspecting your roof, gave you their quotes.

You already know the ending…one quote is way less than all the other ones.

But why?

It turns out that upon the roof inspection, the spray foam roof was coated only once on the initial installation.

This turns into a problem when granules were projected into that single layer of coating.

The problem is that over the years, some of the granules were worn down and removed from the roof due to wind, rain, heavy storms, foot traffic, and many other naturally occurring circumstances.

NOTE: Granules wearing down is something that happens on every single spray foam roof over the years.

Since the roof only had one layer of coating, and those granules were embedded into that coating upon application, they were ingrained into the spray foam of the roof as well.

Here’s a photo of what this looks like after initial installation:

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You can clearly see the black lines (granules) go past the topcoat of coating and get into the foam.

After years of rain, foot traffic, etc. when those granules wear away, it’ll leave the spray foam roof exposed (white lines), like this:

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While spray foam has many advantages over other roofing systems, it’s #1 weakness is UV rays. UV rays will degrade spray foam around 1/16th of an inch every year.

That’s why it’s ultra-important to have coating protecting your spray foam roof. In order to do that properly, a basecoat and a topcoat of coating are necessary.

Here’s how the foam is protected when you have the necessary two coats:

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You clearly see here, that even though the granules wore away from the topcoat, the base coat is still there to protect the foam.

Now for some real photos of what happened on that roof!

After 15 years of having the foam exposed, you can see that the UV rays damaged the spray foam roof. Here are some photos showing holes in the foam where granules used to be:

picture #3 of bad coating on a spray foam roof


picture #2 of bad coating on a spray foam roof


picture of bad coating on a spray foam roof

So why was the quote for the recoat so different between contractors?

One roofing contractor quoted to clean the roof as is and simply install new coating.

There is a huge problem.

A recoat on this roof cannot be performed like any other spray foam roof due to the damaged foam.

In order to correctly recoat this roof so that it performs how it was designed too for the next 15 years, you need to remove all the damaged foam by scarification, then spray new foam down, and then apply two coats of coating with the final coat having the embedded granules.

If the damaged foam is not removed, the roofing system will fail because the coating will peel, and the foam underneath will be exposed to UV’s again.

When you add in the removal of 40,000 sq. ft. of damaged foam, and then adding 40,000 sq. ft. of foam back onto the roof, your quote is going to be much higher than someone skipping those steps.

That’s why when you’re comparing roofing quotes, it’s important to know not only what the final cost is, but what work is being done, and if that work justifies the higher quote.

For the $400 painted car example:

That would be comparable to having one painter who’s simply going to clean your car, and then apply paint. $400.

The other painter, who’s $1300, notices you have rust which needs properly removed before painting. In the quote, they will sand the rust areas down completely, add body filler if pits are created in the metal, put a rust inhibitive primer down, then paint.

Because that painter knows if you just apply new paint over rust, it’s going to look crappy in no time, and you’ll be extremely dissatisfied.


Spray foam roofing and the recoating process

Hopefully today you learned a little about spray foam roofing, how and why it gets recoated, and why you absolutely need two coats of coating when using granules.

At West Roofing Systems, we’ve been doing initial installations of spray foam roofing over existing roofs for more than 40 years, and some of the roofs we initially foamed in the 1980’s has been recoated with West a 2nd and 3rd time.

Would you like to learn more about spray foam roofing in general?

We developed an Ultimate Guide to Spray Foam Roofing (no names or email addresses needed), which covers popular topics, such as:

  • How much does a spray foam roof cost?
  • How does a spray foam roof compare to single-ply?
  • What are the pros and cons of spray foam roofing?

And much more!

the ultimate guide to spray foam roofing

About the Author

Greg Palya

Greg Palya is the Digital Content Manager of West Roofing Systems, Inc. He has a B.S. in Marketing from the University of Akron and an MBA in Marketing from Walsh University. When he's not trying to teach others about spray foam roofing and silicone roof coatings, you can find him on the basketball court or golf course.