Polyurethane Spray Foam Insulation


Polyurethane spray foam insulation is a complete insulation cellular thermoset plastic material and air barrier system.  It insulates and air seals walls, floors and ceiling cavities against air movement; including spaces around electrical outlets, baseboards, and where the walls meet windows and doors. Applied as a liquid, the foam instantly expands up to 120x its original size to fill in every nook and cranny. Polyurethane spray foam insulation is a polyurethane plastic predominately made from petroleum or recycled petroleum-based products. Soy and other agricultural contents partially make up certain foams.

Solstice Liquid Blowing Agent is the latest advance in foam blowing agent technology developed by Honeywell. Solstice based formulations have a slightly different reactivity profile which makes the optimization of pressure and temperature more important. These appear to require slightly higher temperatures for processing.  A 3°F to 5°F increase in temperature using the same spray pressure of 1200 to 1400 psi appear to result in a 10 to 15 percent increase in yield as well as an improved R- Value.


When the material is burning (i.e., flaming mode) or when it is exposed to elevated temperatures without burning (i.e., non-flaming mode) is when thermal degradation can take place.  All combustible materials, whether synthetic or man-made, generally produce toxic products when burned. This document highlights toxic products that may be of concern when polyurethanes are thermally degraded, the risks of working in proximity to those toxic products and some worker safety and health precautions to consider.


  • Mix the A-side and B-side in the spray gun to create Polyurethane Spray Foam Insulation. 
  • Mixing is by impingement- A & B streams collide at a high Velocity to mix properly.
  • The spray gun creates a fine mist exiting the gun in a symmetrical pattern, most often a round pattern. To achieve patterns such as flat or spattered, you can use other types of mix chambers.
  • The most common spray gun used in the market today is the Graco AP Fusion with mix chamber sizes 1, 1 ½ , and 2 for most residential and commercial insulation jobs and a 3 for commercial roofing.
  • Within seconds the mixture foams and reacts to form a tack-free urethane foam.
  • Proper pressures and temperatures at the spray gun are important to insure a quality mix of both A&B. This is where the proper Spray Foam Reactor and supporting equipment comes into play.
  • The desired temperatures and pressures will be located on the material Technical Data Sheets.
  • Desired temperatures may need to be adjusted depending on the ambient air temperature, humidity and other uncontrollable conditions. Graco Reactor 2 can assist in storing these recipes to fine tune your spraying. This saves much wasted time tinkering with pressures and temperatures.
  • The material in the drums should be at 70 to 80 degrees.
  • Pressures and temperatures will vary from one foam manufacture to another. Therefore, if you are spraying XYZ company one week and ABC’s the next pay attention to the data sheets provided by that material supplier.


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