Open Cell vs Closed Cell Polyurethane: Which Application is Best for Each?

The commitment of significant resources is required to pull back the curtain and reveal how thermal and acoustic events behave inside buildings. In turn, manufacturers have an intimate understanding of just how the air flows and sound propagates within a structure. Open cell and closed cell polyurethane compounds are the spray-in-place formulation of choice here, with each insulating medium delivering slightly different heat insulating and sound deadening characteristics, properties that target everything from an improved R-Factor to a superior moisture barrier.

Exploring Physical Characteristics

First of all, both polyurethane forms are popular insulating solutions, but they differ in consistency and function. The open cell type cures as a spongy mass. It’s lightweight, gives slightly to the touch, and makes for a formidable sound absorbing barrier. Closed cell products require a special blowing agent, a chemical that hardens fast so as to prevent the bubbles (cells) from bursting. You can imagine the denser closed cell as a tiny sealed chamber holding an inert gas (typically carbon dioxide), and this seal providing both a physical and gaseous barrier, one that ramps the R-Factor up to a whopping 6.5 while adding dense mechanical strength. Of course, open cell and closed cell polyurethane have more to offer, with the affordability of the open form providing a tempting selling point, for sure.

Clarifying Application Differences

Let’s not ignore the handy features that are available when you install an open cell insulating product. Open cell insulating sprays cost less, and the accessible structure increases airflow while cancelling noise. Water transmission is possible and humid air can escape. Popular in roofing projects, this important feature stops wood from rotting. Additionally, the sponge-like consistency is forgiving when seasonal creep causes structural parts to expand and contract. But this isn’t a competition, only an explanation of important differences. For example, closed cell foams are denser, which is a desirable reinforcing feature, meaning it adds structural strength. Closed variants are also far less permeable than their open cousins, which equals a product that can be used inside or outdoors. For strength and thermal insulation, lean towards the closed bubbles but do consider the open form when seeking noise attenuation.

Both forms act as powerful barriers, but open cell and closed cell polyurethane forms carry significant differences. One is slightly permeable; the other is not. Additionally, blowing agents cause concern. Environmentally superior in this one aspect, open cell foams use plain water, but a closed cell spray requires chemicals to ensure the material hardens quickly.