Currently Reading

Open or Closed Cell Insulation: The Age-Old Question


Open or Closed Cell Insulation: The Age-Old Question

Both insulation types are proven and effective commercial solutions, but each product has its own unique set of qualities

July 12, 2012

While both open cell and closed cell spray foam insulation are proven and effective commercial solutions, each product has its own unique set of qualities and is more ideal for certain applications. Armed with this knowledge, specifiers can make better educated decisions when it comes to product selection.

A typical 0.5 lb per cubic foot light density open cell product forms into a soft and flexible, yet air tight seal, and therefore accommodates a building’s normal structural movement and shifting over time. As a vapor permeable application, it supports bi-directional assembly drying and provides better sound absorption than its closed cell counterpart. Open cell is also a lower cost product and uses an eco-friendly water-based blowing agent for application.

Meanwhile, 2.0 lb per cubic foot medium density closed cell SPF offers a higher R-value of 6.0 per inch (as compared to open cell’s 3.7 per inch), impact resistance, and a hard, rigid texture which increases the wall racking strength. Furthermore, its low vapor permeance qualifies it as a class II VDR (vapor diffusion retarder), enabling building owners to meet International Code Council building code requirements for vapor retarders where required.

For example, in Marine Zones 4 and 5, ICC codes require Class I (less than 0.1 perms) or Class II (between 0.1 and 1.0 perms) vapor retarders on the interior side of framed walls. While closed cell fits the bill, open cell would require a separate vapor retarder. 

As a side point regarding open cell, a 6 mil poly vapor retarder is commonly used with fiberglass insulation materials. However, the material requires seeming and can be punctured during application of the drywall. Consequently, the use of vapor retarder paint directly over the insulation surface is recommended.

Another important rule of thumb for open vs. closed cell is the fact that open cell is limited to interior applications whereas closed cell can be installed on the building’s exterior as well.

While these are some general guidelines, each project must be evaluated by its own unique set of requirements, including climate, budget, and performance requirements.


Written By

Sr. Engineer

John Broniek is Senior Engineer with Icynene and has been involved in improving the energy efficiency and durability of buildings throughout North America since 1990. During that time he has gained valuable experience in building science, research, project management, field work and industry training. He is currently responsible for providing product use recommendations to external audiences including designers, applicators and building owners as well as being a building science technical resource.

Related Stories

Sponsored Pink Next Gen™  Fiberglas™

Owens Corning® Unveils PINK Next Gen™ Fiberglas™ Insulation

Owens Corning, the insulation industry's most trusted brand, announces the introduction of PINK Next Gen™ Fiberglas™ insulation, an advanced…


OX-IS Structural Insulated Sheathing

Rely on all-in-one OX-IS to deliver high R-values while meeting building code requirements for sheathing, insulation, and water-resistive and air…

Sponsored Roost - Nudura ICF Project on Bainbridge Island
Building Envelope

Thoughtfully Designed Homes With ICF

Houses designed with authenticity, thoughtfulness, and materials that were beneficial to both the residents and the environment. ICF construction with a tight building envelope.


More in Category


Create an account

By creating an account, you agree to Pro Builder's terms of service and privacy policy.

Daily Feed Newsletter

Get Pro Builder in your inbox

Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox.

Save the stories you care about

Lorem ipsum dolor sit amet lorem ipsum dolor sit amet lorem ipsum dolor sit amet.

The bookmark icon allows you to save any story to your account to read it later
Tap it once to save, and tap it again to unsave

It looks like you’re using an ad-blocker!

Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. There are two ways you can keep reading:

Disable your ad-blocker
Disable now
Subscribe to Pro Builder
Already a member? Sign in
Become a Member

Subscribe to Pro Builder for unlimited access

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.