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DIY Spray Foam Insulation: An Intro

DIY Spray Foam Insulation: An Intro

So, you're building a home or metal building and would like to install spray foam insulation. Congratulations! Spray polyurethane foam is energy efficient, durable, and creates a comfortable environment by keeping buildings warm in the winter and cool in the summer. With that said, there's a good chance you've stumbled upon this blog because those no-good cotton-headed spray foam contractors are bidding too darned high and now you're scouring the world wide web for information to simply install the foam yourself!

Well, you're not alone. I have had many conversations with building owners and contractors who've determined that they would rather purchase their own spray foam equipment, attempt to install foam themselves; all in an effort to trim their overall budget. - I can understand that! - I can also understand developing a sense of bravado after watching YouTube videos and speaking to a materials rep touting his 3-day spray foam certification class.

The purpose of this upcoming blog-series is to empower and enlighten anyone seeking to purchase their own high-pressure spray foam equipment for a DIY project, arm them with enough information to make an educated decision, and, if I've done my job well enough, dissuade them from following through with it.

Now, because I could write for hours and hours about the small nuances involved with spray polyurethane foam, I will use this first post as an introduction to its many important components and then use subsequent posts to dive deeper into each component.

[NOTE: You can also listen to us chat about these same topics on our podcast show @TheTitanApplicatorsPodcast]

Before I begin, let me throw in a disclaimer: This information is not intended to be a substitute for the extensive training that is necessary to become a qualified spray polyurethane foam applicator; nor will it provide key pieces of information that can only be learned through hands-on experience. Titan Applicators, including the author of this blog post, shall not be held liable for any expenses resulting from loss, damage, or accident caused by misuse of the information provide.

Areas of Focus: Upcoming Blog Topics


Manufacturing spray polyurethane foam requires the handling of hazardous chemicals. Specifically isocyanates, an allergen, and therefore a potential sensitizer. Working with isocyanates can be dangerous and may cause an allergic reaction resulting in bodily harm from exposure.

  • What type of personal protective equipment is required?
  • What kind of health risks are there for occupants of a foamed building?
  • Is spray foam combustible?

There are many factors that must be considered before, during and after the application of spray foam insulation. Many of which we will review, in depth, in a separate and dedicated blog post. In the meantime, if you wish to do your own research, there is plenty of information on-line by credible sources. Here are a link to a couple:

American Chemistry Council, Spray Polyurethane Foam Association

The Science Stuff

If you purchase a spray foam rig, you're basically purchasing a small, self-contained manufacturing facility to produce your own plastic product. Good polyurethane foam is formed by putting two unique liquid components through the correct combination of heat, pressure and spray gun configuration. The mixing occurs by impingement: meaning the A-side chemical (known as ISO or Isocyanates) collides with the B-side chemical (known as Resin or Polyol-polyether resin) at a high velocity to mix properly. - But here's the kicker: the correct combination of heat, pressure and temperatures will vary from one foam manufacturer to another, from one season to another, and one elevation to another. In addition, the correct combination of heat, pressure and temperatures will be contingent to the ambient air temperature, the humidity levels and other uncontrollable on-site variables.

  • So, what is the chemical composition of these two liquids?
  • What is the process they have to undertake to become foam?

Here is a good document from the American Chemistry Council to reference: Spray Polyurethane Foam:Guidance on Sampling Techniques for the Inspection of Installed SPF


As it was previously indicated, producing good spray foam requires the correct combination of heat, pressure and spray gun configuration. Getting even one of these factors wrong can result can cause some major, even life threatening, issues.

Spray foam systems are designed to be mixed in a 1:1 ratio by volume (within 2 percent). The proportioner (also referred to was the reactor) is designed to assure that both the "A" and "B" components are delivered to the spray gun at consistent ratios.

There are several manufacturers of spray foam proportioners. Some are air driven and other are electric/hydraulic powered. The selection of your system will largely be determined by your needs vs. the machine's output capabilities. - With that said, the necessity for auxiliary equipment, such as generators and compressors, and the necessity for auxiliary upgrades, will be directly tied to the side of the proportioner you choose.

Other important pieces of equipment, in no specific order and not limited to, are: drum pumps, heated hose, spray guns, and air dryers. - We will cover these items, in detail, in its own dedicated blog post.

  • What type of spray foam systems are there?
  • Will these systems meet your needs?
  • What kind of maintenance is required on a spray foam rig?
  • Are all spray foam guns equal?
  • Trouble-shooting, troubleshooting, troubleshooting

In the meantime, check out SPFA's technical document specific to spray foam equipment (*you will need to provide your personal contact information to view the documents): SPFA-137


A wide range of SPF systems are available in various densities, various limitations, combustibility characteristics, different approvals, and much more. Each product offers unique benefits that a professional spray foam contractor can explain to help end-users navigate which foam is most appropriate for a specific application, climate or building code.

  • Which foam manufacturer will you use?
  • How much product do you need?
  • What is a reasonable cost for material?

Once we reach this topic, we will provide a list of spray foam options and give each manufacturer an opportunity to speak for themselves and their products.

Building Science & Building Codes

If you are going to install your own spray foam insulation, you need to have a thorough understanding of two very important things: Building Science & Building Codes. Unfortunately, they don't always go hand in hand.

A very brief and small example of understanding building science is to understand vented and unvented attic assemblies. A vented attic assembly should not communicate with the conditioned space of your building. Rather, it should be coupled with the exterior. Whereas unvented assemblies fall into two categories: 1) systems where condensing surface temperatures are not controlled and 2) systems where condensing surface temperatures are controlled. Understanding these different assemblies, relative to your location, are essential for controlling things like moisture, mold, decay, ice damming.

A brief example of understanding building codes nuances is to have a firm understanding vapor barrier requirements relative to your climate zone. For example, in climate zone 5 and higher, a Class 2 vapor retarder is required on the interior of an open-cell spray foam layer. But, if you install high-density closed-cell foam, a class 2 Vapor retarder is not required for those climate zones because it already qualifies as the vapor retarder.

  • What climate zone do you live in?
  • Which IECC code does your local building department recognize?
  • Is a thermal barrier required over the foam you are installing?
  • Is an ignition barrier required over the foam you are installing?

Spray Foam Application

Once you've purchased your equipment, chose your product, confirmed your local building code requirements, how much product you will need, what type of product you will need and who is going to help you WHEN something goes wrong - it is now time for spray foam application.

If you have any apprehension and/or questions about how to apply a certain product, that should be a good indicator that you aren't prepared to perform the work. Nonetheless, questions about how to apply your product, and what conditions are optimal for a successful application, should always be directed to the supplier's customer support or technical support contacts.

If you are applying a closed-cell foam, I'd like to point out that some manufacturers are claiming to have a "high-rise" foam which allows you to install their product art greater depths per pass.  - Sounds great! Who would't want cut down their work time? - Well, in my opinion, there many factors to consider before an applicator can determine whether or not a high-rise closed-cell foam is a good idea. Not only that, but experience has proven to me that what a product representative says about their foam's capabilities will occasionally contradict what the data sheet says the foam can actually do. - Just be sure to know exactly what you are installing and how to properly install it because a foam-caused fire will be a sure way to put your project behind schedule and over budget. - Spraying bad foam may not immediately recognizable to the untrained eye.

  • How to determine if you are spraying "bad"?
  • Why isn't your spray pattern even?
  • What if your foam pulls away from the studs or falls off the wall?
  • What type of site preparation will there need to be?
  • Do you need to ventilate?


As indicated before, if you purchase a spray foam insulation rig, you are becoming a manufacturer. Unlike most other trades, spray foam is not a pre-manufactured good. You are taking raw chemicals and processing them on-site to make the finished product.  In the world of a professional spray foam applicator, its the sole responsibility of that installer and his or her business to control the factors surrounding the entire process; the equipment, the temperatures, material handling, safety of themselves and others, troubleshooting, maintaining certifications, process the chemicals properly, guarantee a well manufactured product, etc., etc..

Obviously, with most "DIY" projects, having no experience isn't always a deal breaker. I've personally made repairs and upgrades to my properties, all through DIY websites and YouTube. However, there's a subtle difference between disappointing my wife because the ship-lap is crooked and risking my family's safety by attempting a job so highly specialized that it takes years of training to handle on your own.

The choice you have between DIY and hiring a professional spray foam contractor is more than just a matter of money. It's a careful balancing act between savings and a laundry-list of factors. - Most of which I will do my best to explain in posts to come.

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