Difference Between Open Cell and Closed Cell Foam (With Table)

Insulation is very important if anyone wants to build an object inside the building. Insulation that is used in buildings is basically for thermal use, i.e. thermal insulation. Besides that, there are other insulation as well like fire insulation, acoustic insulation, impact insulation etc. Insulation is very important both for the environment as well as for economic purposes. Two types of foams are used for insulation, i.e. open-cell and closed-cell foam.

Open Cell Foam vs Closed Cell Foam

The difference between open-cell and closed-cell foam is that the composition of the open-cell foam is very light, and the composition of closed-cell foam is very dense. Open-cell foam, as the name is, its cells are open, which makes the foam softer and flexible material. Whereas in closed-cell foam, as the name is, cells are closed. This puts pressure on the cells, which makes it’s so rigid, hard and more stable than open-cell foam.

Open-cell foam has a wider application, and majorly it is used in medical packaging, electronics, furniture upholstery, seat cushions, power equipment etc., for shock absorption, insulation and sound absorption. The most common foam which has open-cell in it is polyurethane foams. This foam is considered one of the strongest open-cell forms because of its resistance power with oxygen. They are usually very lightweight and are less dense, and are soft and spongy in looks.

Closed-cell foam is a very strong, dense material that is closely knit together. They are very flexible for the plastic rubber material. Closed-cell foam cells are so close that they are like a bubble or like balloons trapped together, but they are not connected. Their density is three times more than the open cell, which is about 1.75 pounds per cubic foot or more. It can expand up to 1” of thickness as its R-value is very much higher in comparison with open-cell foam.

Comparison Table Between Open Cell and Closed Cell Foam

Parameters of ComparisonOpen Cell FoamClosed Cell Foam
Blowing agentWaterChemical
AdvantagesHigher moisture absorption and interconnectivity.Higher cushioning
DisadvantagesWeaker in structure and can breakdown materialsHas undesirable chemicals.

What is Open Cell Foam?

Open-cell foam consists of cells that are not encapsulated, i.e. not closed. So because of it, it becomes a very much soft and flexible material. The density of the open-cell foam is very much less in comparison with closed-cell foam, i.e. .5 pounds per cubic foot. Its R-value is very much limited, and so because of that, its usefulness of insulation becomes lower. But it can expand three times in thickness, and its expansion is higher than closed-cell foam.

Open-cell foam benefit is that because of its larger expansion, it can move to areas that are hard to reach in a home. It is considered very good for soundproofing and absorption as it can fill every area between studs. They are very much affordable in comparison with closed-cell foam. Open-cell foam cannot be used in the house or in places where there is an extreme weather condition. It is not suited for it. Polyurethane foam sheets are the best example of it because of their sponge-like appearance and soft cushioning.

Because open cell foam is porous in nature, they are not resistant to water vapours. It is very durable, which means that it will not shrink, break or diminish. Open-cell foam doesn’t have any ozone-depleting gases and doesn’t contain any volatile compounds. It has a lot of uses like low-cost furniture upholstery, Soundproofing for buildings, Foam protective packaging, Vapor, moisture and air permeable required application and Interior design projects.

What is Closed Cell Foam?

Closed-cell foams are completely encapsulated and are compressed together. It is so much compressed that even moisture and air can’t pass through it. It is very much dense, strong and rigid than open-cell foam. It has three times more density than an open cell, i.e. 1.75 pounds per cubic foot. Its R-value is very much higher, i.e. 6 to 7 per inch, which makes its rating higher and more convenient it can keep the heat in and outside the structure.

Closed-cell foam has a minimal expansion rate, i.e. 1” thickness when water is sprayed. It has a lot of benefits, like it is best for robust insulation where space is limited. Their closed-cell foam can reach its maximum capacity, i.e. 2x and become rigid and stronger. Because of its rigidity, closed-cell foam is successful in maintaining the structural integrity of the building. It also acts as a vapour barrier, so very little chance is there that water and moisture can penetrate through it.

It also protects buildings and houses from water damage. Closed-cell foam can be made up of many materials ranging between polyethene, polystyrene, EVA, rubber to polypropylene etc. It is extremely reliable for any kind of environment, whether exterior or interior. It is best for providing sound and heat insulation. It has excellent resistive nature towards leakage. They have very popular uses like cushioning, padding, insulation, and gaskets.

Main Differences Between Open Cell and Closed Cell Foam

  1. Open Cell foam has a very light composition. It is soft and durable. Closed-cell foam has a very dense composition which makes it strong and rigid.
  2. The blowing agent of open-cell foam is water. The blowing agent for closed-cell foam is chemicals.
  3. The expansion rate of Open cell foam is three times higher than closed-cell foam. The expansion rate of Closed-cell foam is very minimal.
  4. The R-value of open-cell foam is lower, i.e. 3.5 per inch, which limits its insulation. The R-value of closed-cell foam is higher, i.e. 6 to 7 per inch.
  5. The advantages of open-cell foam are that it has higher moisture absorption and interconnectivity. The advantage of closed-cell foam is that it has higher cushioning.
  6. The disadvantage of open-cell foam is that it has a weaker structure and can break down materials. The disadvantage of closed-cell foam has undesirable chemicals.


Both open-cell and closed-cell foam are cellular materials that are made up of foam. Both are similar in appearance, but they should not be mistaken as one product. As both have different properties and their performance on a product is also different. Both have different applications. Open-cell foam is less costly than closed-cell foam. 

Closed-cell foam can be used in all weather conditions, but open cells cannot. Both have an air seal. Open-cell foam has a sound dampening capacity which is minimal in closed-cell foam. Closed-cell foam is considered best for insulation because of its rigidness and resistivity to water vapours.


  1. https://www.sciencedirect.com/science/article/pii/S135964549900097X
  2. https://link.springer.com/article/10.1007/s11661-018-4867-x
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