Open Cell vs Closed Cell Spray Foam

Before we dive into the pros and cons of open cell vs closed cell foam insulation, it’s important to note that they’re both superior in their own ways. It is in light of this that industry experts recommend using a combination of insulating materials.

In this guide we will examine open cell vs closed cell foam and help you pick the best option for your project.

What’s the Difference Between Open Cell and Closed Cell Foam Insulation?

Open and closed cell foam have different strengths and weaknesses, and one is not necessarily better than the other. Across residential and commercial properties, different types of insulation will be needed to get the best of the property.

We can categorise the properties of cell foam insulation into the following categories: structure, application, density, U-Value and expansion.

Let’s start by looking at the differences between open and closed cell foam.


Open cell foam insulation has a lighter ‘foamier’ texture than its counterpart. The cell composition of this component is not completely encapsulated, allowing for a flexible and versatile spray foam insulation.

On the other hand, closed cell foam insulation takes a more rigid format. The cells are completely closed to provide ultimate robust and rigid properties whilst locking out any forms of moisture, water and humidity.

These two cell foam insulators hold opposing structures that can be applied in different areas for optimum results. For example, in areas that are typically susceptible to water damage, it would be preferable to use closed cell insulation in order to contain and prevent water leakage.

However, the open-cell foam works better to absorb sound, so can be used to prevent the transfer of sound between rooms, neighbours, or even the outside environment such as cars and planes.


Both methods of insulation should be applied by a fully trained and accredited expert, such as those found at Eco Spray-Foam Systems. The two components that form the insulant are run through the pipes into the application device, combined with a blowing agent and applied to the area. It’s the reaction between the two products that give the products their expansive capabilities, completing a full fill to build an air barrier and stop air leakage.

Residential properties mostly use open cell foam insulation due to the cells' ability to get in all the nooks and crannies, because of its lightweight and flexible components. This option is also a great money saver as areas usually only require one coating of open cell foam insulation, the foam spreads rapidly covering the entire areas desired. Due to its open-cell buildup, this variation of spray foam insulation holds a much sought after soundproof component. This form of insulation is great for soundproofing, and therefore is commonly used in attic floors, roofs, and above grade exterior walls.

On the contrary, closed cell foam insulation is specifically suited to commercial and industrial properties. Due to its inherently strong, robust and rigid nature, it provides the perfect structural assistance for these types of properties. However, this is not to say that it can’t be used in residential properties. Given that roofing areas are subject to heavy rainfall, they will benefit from using closed cell foam insulation. Other applications of closed cell insulation would be basements, crawl spaces, pole barns, metal buildings and exterior applications.


On average, open cell foam insulation has around a 0.5lbs per cubic foot density. This provides a cell formulation with the flexibility and lightweight properties previously mentioned.

In contrast, closed cell foam insulation can reach over 3x its counterpart, averaging at 1.75lbs per cubic foot, or more. This density allows for a more robust cell composition, providing rigid features and structural integrity.


The U-Value of an insulation material indicates how much heat is transferred through a product. Therefore, the lower the number, the less heat is travelling through the product - the better the material is acting as an insulating product. Our open-cell products have a standard U-Value of 0.038.

In regard to closed cell foam insulation, this product thrives on its U-Value, and the fact that it’s a superior heat-resistant and insulating material. Our closed-cell products have a standard U-Value of 0.025-0.027, depending on the thickness of insulation used. A standard 25mm application is normally enough to eliminate the risk of condensation and moisture build-up. When the insulation depth is increased in inhabited spaces, we recommend a depth of at least 50mm.


As previously mentioned, open cell foam insulation products expand monumentally, averaging 100x its liquid state. This allows it to cover and create an airtight environment. Open cell insulation is designed to reach 100mm of thickness, with only one layer of application.

On the other hand, closed cell products are denser and therefore expand less. This insulation is considered air impermeable at around with a 50mm application, which is around 40x its liquid state. The thicker the insulation the lower u-value you can achieve.

So Which Insulation Should I Use?

In most cases, the answer isn’t as straightforward as saying open or closed cell-spray foam. This is because it will depend on many factors, including the properties and structure of the property you're insulating, what the property will be used for, and your budget.

You can speak to one of our experts to get a better handle on what type of insulation is right for your specific requirements. Please see below for our contact information.

Bespoke Spray Foam Insulation Services

We can deliver state-of-the-art spray foam insulation for all kinds of properties. Whether it's closed-cell or open-cell you're after, residential or commercial, Eco Spray-Foam Systems have got you covered. Our latest spray foam technology can give you the thermally efficient, mould free and water-resistant property that you dream of. Moreover, our spray foam products are environmentally friendly, water-blown and highly effective.

We’ve successfully completed projects across London, Manchester, Essex, Kent and beyond. If you’d like some more information regarding closed cell and open cell spray foam, or any other of our products, then please contact us today.