On the market, spray-on foam is a popular insulation material option. This material itself comes mainly in two types: open and closed forms. Each has its own characteristics, benefits, and drawbacks.
Below, you will specifically read about the closed foam and get your questions answered, such as what is this particular material or is closed cell foam waterproof. Continue reading to find out.
What Is Closed Cell Foam
Spray-on foam insulation is made by entrapping gas within a liquid, in which it is given heat and pressure to transform it into a solid form. Depending on its type, the foam can carry a lot of beneficial characteristics such as sound deadening, shock absorption, surface cushioning, and many more.

As you inspect foam closely, you’ll notice that it consists of tiny bubbles. In the case of closed cell foams, these tiny bubbles aren’t connected to one another as every single of them has a minuscular pocket containing gas. Compared to the open cell foam type, the bubbles are tinier in size and more densely packed. This results in a more suitable and durable nature for heavy-duty usage purposes.
There are many types of closed cell spray foam you can find, each of which has different properties and purposes. Below are four of the most commonly available types:
- Polyurethane foam
Polyurethane foam is among the most widely available category of closed foams. It has the characteristics of being extremely stiff. It tends to be able to maintain shape well, but it can also crumble. Depending on the production process, it may come in a different texture. In the industry, it is used for packaging, knee pads, etc.
- Polyethylene foam
This type of closed foam is extremely versatile in use due to its water-resistant and mildew/mold-proof. Usually, closed cell polyethylene foam is used as sound or heat insulation, protection, or impact dampening material. You can find this material used for broadly varying purposes such as packaging components, water woggle, climbers’ crash pads, to marine safety & flotation devices.
- FloTex foam
In terms of rigidity, this foam is considered medium level. It has a sort of rubbery texture and is used conveniently in the industry for various items such as boat cushions, camping pads, life preservers, boat cushions, and many more. It is a suitable material for marine application as it has water-repelling characteristics.
- EVA foam
While it is quite firm on its own, EVA foam material is a bit softer compared to polyurethane foam. It easily springs back to its original shape, which makes it ideal for different usages such as boating bumpers, sporting tools, helmets, shin guards, knee pads, hot tub insulation, and plenty of other purposes.
Is Closed Cell Foam Waterproof
In comparison to its open-celled cousin, closed foam material has far better water-resistant characteristics. It is due to how the material’s cell structure is so dense, resulting in a natural resilience towards moisture. However, there is also a slight possibility that most types of materials clumped under the closed foams category will experience some water absorption at times.
If you are looking for a waterproof spray on foam, opt for closed foams with the highest density in terms of cell structure. This type of foam is typically applied for water shields inside vehicles or door panels.
Having some questions regarding spray-on insulation foam, such as is closed cell foam waterproof, is very normal, especially for those unfamiliar with the whole insulation material industry. Doing short and quick research regarding the topic can help to make a more sound, informed decision to achieve the desired results.