Lake Austin Build Along: Foam Insulation

Lake Austin Build Along

Foam Insulation

Our Lake Austin build passed its city inspection this week and had open cell foam insulation blown in yesterday. Stone masons were busy working on the home all week and a large group of workmen were on site. By the time the Best Insulation crew had their trailer set up on site, the home was a beehive of activity. Because all windows were covered with plastic sheeting, the house got hot quickly.

foam insulation

What is Open Cell Foam

The type of spray Polyurethane foam (SPF) used in the build distinctly impacts project costs, application methods, and building performance. When foam is installed in a home a cellular plastic is being made on site. For simplicity, think of it as bubbles in a bubble bath. The insulation cures very quickly and of course is dry once cured, unlike the bubbles in a bubble bath.

Open  vs. Closed Cell Structure

Open-cell foam consists of tiny bubbles or cells that aren’t fully encapsulated; they are broken, torn or ripped. Because they’re broken, air fills the open space inside the bubble, which results in a soft, spongy material.

Closed-cell foam differs in that every bubble or cell that makes up the foam is completely encapsulated and packed tightly together. The bubbles aren’t filled with air, but rather a gas that aids foam expansion and insulation properties. This results in an altogether harder material than open-cell foam.

The blowing agent, which aids in forming the bubbles or cells that make up  foam structure, is usually water for open-cell and high-R-value chemicals for closed-cell. Closed-cell foam is roughly four times as dense as open-cell for insulation applications.

Why Open Cell Foam?

Open cell foam insulation is a high performance building material that offers advantages over traditional fiberglass insulation.

Here are a few advantages:

  • Reduced labor and waste
  • Sound proofing qualities
  • Easy application over curved and irregular surfaces
  • Resistance to water damage
  • All-in-one insulator and air barrier
  • Improved indoor air quality
  • Savings on heating and cooling cost

The Install

We sprayed a two-component open cell foam in the lake house. First, two chemical ingredients were mixed together on-site using special trailer mounted equipment. Then, heated hoses conveyed the components to a mixing gun that sprayed the chemicals on the surfaces to be insulated. A chemical reaction began as soon as the chemicals were mixed. The liquid spray  mixture foamed, expanded, and eventually hardened to fill all the void spaces.


Adrian, our project manager, cut this video of spray day. Notice the installers wearing Tyvek™ suits and respirators for protection from chemicals and noxious fumes.


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