off ratio spray foam

The Dangers of Off-Ratio Spray Foam for Commercial Roofing

Greg PalyaSpray Polyurethane Foam Roofing

Imagine you’re a building owner and you have a roof leak.

You research all the commercial roofing systems, the pros and cons of each, pricing, etc.

You know what you want…a spray foam roof.

You get a few quotes and choose the cheapest contractor.

Spray foam installation is spray foam installation…right?

Year 3, your spray foam roof looks like a swamp, it leaks, and you barely have any money left in the budget.

You were told this roof will outlast the building, that it was renewable, etc.

What went wrong?

The answer is that your roof was installed with off-ratio spray foam.

In this article, we’re going to explain:

  • What off-ratio spray foam is?
  • Why it puts businesses in terrible financial situations
  • And how to identify a bad spray foam roofing company

There’s nothing easy when it comes to heating and mixing chemicals to produce a high performing roofing surface. At West Roofing Systems, we’ve seen plenty of other roofing contractors install off-ratio foam over the past 40+ years we’ve been in business.

Let’s get into it…


What is off-ratio spray foam?

Spray polyurethane foam is a product formed by a combination of two chemicals, a polyol resin, and an isocyanate (commonly referred to as the “A side” and the “B side”).

In order for spray foam to develop the ideal surface profile so that it performs how it’s designed to, you need a perfect one to one (1:1) ratio of the A side and B side.

Any spray foam that’s applied in anything other than a 1:1 ratio is off-ratio spray foam.

Off-ratio foam can be resin-heavy or iso-heavy.

A resin-heavy spray foam will look more like a sponge.

An iso-heavy spray foam will be more brittle and crunchier, which can crack very easily.

In either case, if you get a hole in your roof, water will be absorbed into your roofing system.

After 2-3 years of rain, that water can pass through the foam, enter your roof deck, and eventually start a leak into the interior of your building.

If your roof was installed properly, small holes and cracks would not cause a leak. Since spray foam is closed-cell, water will not pass through the system. But with off-ratio foam, the surface profile isn’t the same, meaning water has an opportunity to reach your deck.

Why off-ratio spray foam hurts businesses financially

Most companies have a budget for maintenance and building upgrades, which includes the roof.

If your company saved for 20 years to get a new roof, and that roof only lasted for 3 years before major repairs need to be made, there’s very little money in the budget.

You planned on saving for 17 more years before investing more into your roof.

You might think, “Well, I signed up for a warranty, so all repairs should be covered.”

You try and contact the roofing contractor that did your roof, and no answer. Months and months pass and eventually you’re stuck with a leaking roof and no budget to repair it.

This is why hiring a great spray foam roofing contractor is very important.

There are plenty of ways to identify a great spray foam roofing contractor, but the main characteristics are:

  • They have been in business for decades, not months or years

  • They have certifications from the SPFA, proving they have met requirements (such as team members spraying over 500,000 sq. ft. of spray foam) to achieve certain accolades

  • They have clients you can contact to ask about their roof and how it’s been performing over the years

  • They have been servicing and recoating spray foam roofs for multiple decades

Recoating may sound like a bad job was performed and the entire roof needed redone.


A recoat takes place after the initial warranty is expired.

For example, if you get a spray foam roof installed today, and you would like a 15-year warranty, 25 mils of coating will be installed on top of your spray foam roof.

This is to protect the foam from UV rays, which will degrade foam.

After 15 years, the 25 mils may be worn down naturally through foot traffic, rain, wind, etc. to around 7-10 mils.

In year 15, small cracks and holes (if any) will be sealed with coating, the roof will be cleaned (usually through power washing), and the entire field of roof will be recoated back to the original amount of coating.

In this case, your roof would be installed with enough coating to get you back to 25 mils, putting your roof under warranty for 15 more years.

A spray foam roofing contractor who has recoated the same roof is a good thing. It means they have kept the roof performing great for multiple decades.

They didn’t disappear after 3 years, essentially using your roof as a trial period to see if they can install foam correctly or not.

From a building owner’s point of view, not having to worry about your roof for multiple decades is one less headache in their lives.

NOTE: Another way to compare spray foam roofing contractors is to ask them, “How many square feet of spray foam have you sprayed?” The numbers that come back can tell you who’s the more experienced contractor.

Spray foam can easily be installed incorrectly

There are plenty of ways that off-ratio foam can be installed, including:

  • Spraying outside the manufacturer’s suggested temperature range
  • Storing your materials in the wrong temperature range
  • Improper mixing of materials
  • Improper heating of materials
  • Spraying foam over a wet surface
  • Spraying foam over wet insulation
  • Improper cleaning of spray foam equipment
  • Improper (or no) adjusting in the heating of the gun

There are plenty more, but the point is that spraying foam, while it has tremendous advantages over other roofing systems, can cause major headaches to a building owner.

A spray foam roof done right

A building owner wants the roof to perform how it’s supposed to. Leak-free, provide some energy savings, and to not have to worry about it for a long, long time.

Installing a spray foam roof with the right contractor can do just that.

If you’d like to learn more about West Roofing Systems as a company, please check out our website.

If you’re interested in starting a conversation about your current roofing issues, please fill out a request for quote form and we’ll contact you ASAP.

When we’re done with that conversation, we can send you a giant list of clients whose spray foam roofs we’ve recoated multiple times.

Request a Quote to help solve your roofing headaches

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.