Closed-Cell Insulation Thickness in Oregon

Closed-Cell Insulation Thickness

Choosing a bad spray foam contractor in Oregon could cost you a lot more money than you think. Make sure you get the right advice on Closed Cell Insulation Thickness from a trusted and reputable spray form contractor.

The answer is 2” closed cell spray foam in the walls and 3” closed cell spray foam under the roof.

All reputable spray foam companies would recommend the same. Unfortunately, we have a lot of spray foam companies under pricing and under delivering, providing incorrect information and supplying poor quality workmanship. Be careful on choosing the right spray foam company in Oregon.

Above is the Heat Flow Reduction chart that illustrates why there is no need to install any more than 3” closed cell spray foam. This amount provides a heat flow reduction of 96%. If we double that thickness, the heat flow only goes up a little over 1% which equated to an almost immeasurable/insignificant amount of energy savings. This is the diminishing rate of return of foam and why we only recommend 2” closed cell spray foam in the walls (94% heat flow reduction) and 3” closed cell spray foam under the roof.

While you will receive a 94% heat flow reduction with only 2” of closed cell spray foam insulation, we recommend a minimum of 3” under and roof deck or in any attic assembly.

A typical roof assembly is subject to a significant increase in temperature due to the radiant heat gain from the solar exposure of the roofing material. The 3” of Closed Cell Spray Foam will guarantee the 96% heat flow reduction which is needed for this increased heat gain.

Large temperature swings in a roof assembly could cause an increase in moisture or vapor drive and the 3” of Closed Cell Spray Foam will almost eliminate the thermal drive which carries the moisture. (Vapor drive=latent moisture driven through an assembly by a thermal drive). This Vapor drive will vary from area to area based on the climate zones and the average heat days per year and is generally calculated by a WUFI scale for condensation.

Business owners looking for Commercial insulation or home owners looking for residential spray foam insulation can save thousands of dollars by following the data provided by The Energy Modeling Agency.

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R-value per inch in practice

The research and data provided from The Energy Modeling Agency shows how little spray foam is need compared to what code required. For more information please view the The Energy Modeling Agency website.

The ideal thickness depends on the application and climate, but general recommendations are:

The thicker the insulation, the higher the R-value and the better it prevents heat loss, air leakage, and moisture infiltration.

Closed-cell spray foam has an R-value of approximately 6.0–7.0 per inch , making it one of the most efficient insulation materials available.

Thickness requirements vary based on local building codes, but most residential and commercial projects need at least:

Yes! Spray foam is applied in layers, allowing for additional thickness if needed. However, each layer must be properly cured before applying the next.

Yes. Over-applying spray foam can lead to diminishing returns, unnecessary costs, and improper curing. The recommended thickness ensures maximum efficiency without waste.

Thicker insulation provides a better moisture barrier, reducing the risk of condensation, mold, and mildew—especially in basements, crawl spaces, and roofs.