Open-Cell vs Closed-Cell Spray Foam Insulation: The differences that matter

Going with spray foam insulation for home? Baffled over which one is best – Open-Cell spray foam vs Closed-Cell spray foam? We’re here to clear all your doubts.

Speaking straightway, no-two spray foams – Open-Cell or Closed-Cell are better than the other. Anyone or combination of two could be the best solution. Learn the differences between two to make better choices for lifetime. After all, foam insulations are just a one-time expense in a lifetime. 

In this quick post, you’ll learn key things that matter before purchasing open-cell or closed-cell foam insulation.

Open-Cell vs Closed-Cell Spray Foam Insulation

Difference between Open-Cell and Closed-Cell Spray Foam

Merely looking, both open cell foam and closed cell foam may seem the same. However, both of them insulate the house differently.

The difference lies in small bubbles that expand after spraying the liquid. Both the sprays are liquid chemical solutions that are applied with a sprayer at jobsite.

 

Open-Cell Spray Foam Insulation

Closed-Cell Spray Foam Insulation

Nature

Soft, flexible, lightweight, breathable

Rigid

Compressibility

High

Low

Water-Permeability

Water can pass-through

Water cannot pass-through

Durability

Poor

Excellent

Spray Expansion Rate

Fast and big

Slow and small

R-value

3.5

7

Price

Inexpensive

Expensive

Air-seal

Attainable per 3.75 inch thickness

Attainable per 1 inch thickness

Climate zone

Warmer regions

Extreme climate conditions

Key-features

High sound-resistance

Rigid, stays solid even when bumped with heavy equipments

Ideally,

Where to use

Nooks & crannies

Exposed exteriors, basement, etc

Future-Proof

Good for future renovations like infusing electric wires through open-cell

Good to avoid mildew and mould in high humidity regions

Let’s look deeper into it.

Open-Cell Spray Foam

When it is sprayed, the bubbles in Open cell foam insulation expands rapidly leaving behind the points at which a bubble connects with the other. So, there is plenty of air gap left between each bead.

It has an average density of 0.5 pounds per cubic foot.

Pros

  • It is inexpensive
  • It is soft, flexible, lightweight, and breathable
  • On an average, it has lesser R-value of 3.5 per inch
  • High expansion rate, meaning you require overall lesser foam to insulate
  • High compressibility. When pierced or punched, easily returnable to its original state
  • Provides air-seal per 3.75 inch thickness
  • Easy-to-cut or Easily trimmable
  • It has good sound-resistance. Twice as when compared to closed-cell.
  • Perfect for filling awkward gaps, nooks, & crannies
  • Popularly used for attic insulation, wall insulation, vaulted/cathedral ceilings, and similar
  • Easy-to-work with. Making electrical wiring through open-cell is easy
  • Perfect for warmer regions

Cons

  • It is water-permeable, meaning water & moisture can easily penetrate through it, if exposed. Effectiveness intact when dried up
  • Not Ideal for climate zones with extreme weather conditions. Eg, Extreme colder regions, floody areas
  • It is highly flammable but flame doesn’t spread swiftly
  • OFF-gassing, when not applied properly, causing health-risks

Closed-Cell Spray Foam

When it is sprayed, the bubbles in Closed-cell don’t expand as suddenly, leaving behind interconnected closed air pockets. So, there is less air space between the two cells as bubbles are densely packed.  

It has an average density of 1.75 pounds per cubic foot.

Pros

  • It is expensive
  • It is rigid
  • On an average, it has a higher R value of 6.5 – 7 per inch
  • It is 100% moisture & water-impermeable, meaning it blocks water & mildew, if exposed
  • It is highly durable. Stays intact even when bumped with machinery or hard items
  • Acts as a vapour barrier
  • Provides air-seal per 1 inch thickness
  • Popularly used for exposed exteriors, basement, roofs, stud cavities, etc
  • Perfect for smaller areas where space is an issue
  • Perfect for colder regions

Cons

  • Slow expansion rate, meaning you require overall more foam to insulate, consequently more labour costs
  • Low compressibility
  • Difficult to trim
  • It is highly flammable but flame doesn’t spread swiftly
  • OFF-gassing, when not applied properly, causing health-risks

Note: Fire hazards are rare, and almost nil on proper application by labour

Open-Cell vs Closed-Cell Spray Foam: Head-to-Head Comparison

Types

Open-Cell Spray Foam:

It is soft and pliable. As bubbles rupture leaving behind struts at which two beads connect each other, the open cell foam insulation does expand at massive-fast rates.

There is plenty of air-space in between two cells, that is why it is extremely breathable. Also, the presence of a lot of air makes it super lightweight.

Closed-Cell Spray Foam:

It is rigid. As bubbles don’t rupture leaving behind interconnected closed air pockets, the closed cell foam does expand at slower rates.

There is less air-space in between two beads, that is why it is hard & solid. Consequently, it is a bit heavier in weight when compared with open-cell spray foam.

R-Values

Open-Cell Spray Foam:

As it is thin and light, R value is lowest in open-cell. On average count, it ranges between 3 to 3.5. Though R value also depends on manufacturer brands. A high-quality open-cell spray foam can have a little good R value and a cheap-quality open-cell spray foam can have extremely poor R value.

Closed-Cell Spray Foam:

As it is thick and rigid, R value is highest in closed cell foam insulation. On average count, it ranges between 6 to 6.5. Though R value also depends on manufacturer brands. A high-quality closed cell insulation spray foam can have the highest R value up to 6 or 7. Meaning, due to good thermal performance, you get better air-conditioning inside home and high energy-savings.

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Life Expectancy

Open-Cell Spray Foam:

It is Short-lived when compared to closed-cell spray foam insulation. As water can penetrate through open-cell, it is prone to discolour and damage. Also, it can attract mould, mildew, and ants (To avoid ants, pests, rodents, & termites, do not fix it in the basement). Even though, when water dries up, the open-cell gets intact, no efficitivity compromised.

Closed-Cell Spray Foam:

It is durable when compared to open-cell spray foam insulation. One reason behind it is that closed cell foam insulation is rigid and hard. Because of rigidity, it blocks water paving its way inside. Water seeps through its open cracks but just puddles on the top.

Density

Open-Cell Spray Foam:

It has a density of 0.5 pounds per cubic foot.

Closed-Cell Spray Foam:

It has a density of 1.75 pounds per cubic foot or even more in case of some brands.

Expansion

Open-Cell Spray Foam:

It has a high expansion rate, almost more than 100-300 times its actual size. As bubble cells rupture leaving behind only its struts, it is thinner by appearance and has lesser air-sealing capacities.  

Closed-Cell Spray Foam:

It has a low expansion rate, almost 33 times its actual size. As bubble cells don’t rupture leaving behind closed interconnected air pockets, it is more dense by appearance and greater air-sealing properties.

Blowing agents

Open-Cell Spray Foam:

It uses water as a blowing agent.

Closed-Cell Spray Foam:

It uses other chemicals as a blowing agent.

Moisture-permeability

Open-Cell Spray Foam:

It allows moisture & water to penetrate through it. A good-brand open-cell spray foam retains up to 5% of its weight in water. A cheaper-quality open-cell spray foam insulation retains almost up to 75% of its weight in water.

Closed-Cell Spray Foam:

It blocks moisture & water. Closed-cell spray foam insulation is 100% water-impermeable.

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Sound-sealing properties

Open-Cell Spray Foam:

It absorbs sound waves so blocks the sound to greater extents.

Closed-Cell Spray Foam:

As it is dense & tight, it cannot block sound waves as well as open-cell.

Cost

Open-Cell Spray Foam:

Open cell foam is quite cheaper than closed cell foam as you require less material due to high expansion rate.

Closed-Cell Spray Foam:

Closed cell foam is more expensive than open cell foam as you require more material due to low expansion rate.

When to use Open-Cell insulation?

You can use Open-cell insulation in small corners, awkward gaps, nooks, narrow passageways, & crannies. This way, it insulates the hard-to-reach places in a good way!

Remember ! : When applying Open-cell insulation, insert additional vapour barrier to avoid condensation.

When to use Closed-Cell insulation?

You can use closed-cell to insulate the basement, attic insulation, enclosed existing walls, floors & ceilings, non-vented low-slope roof areas, foundation walls, unfinished walls, etc. As it is 100% non-porous, it always keeps the main home areas safer.

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What is cheaper Open-Cell vs Closed-Cell?

One cannot predict price affordability in first-look. You may think, “open-cell is cheaper and closed-cell is expensive”. However, that’s not the right scenario! After project completion, you may pay higher with open-cell and vice-a-versa.

As open-cell spray foam insulation accommodates larger spaces with smaller material, it could be cheaper. The reason being the labour & installation costs are also cheaper as effort & time-required is lesser. However, an open cell foam insulation may require an additional vapour barrier too which can increase costs.

As closed-cell spray foam fills smaller spaces, it could be expensive. The reason being the labour & installation costs are also expensive as effort & time-required is more. However, it is water-impermeable, causing water fall over it to block, spread otherwise, and create bigger problems & costs in the future.

Also, both open-cell and closed-cell might require a shield with thermal barrier to prevent fire dangers, which is an additional cost.

In short, both can be cheaper if you do the smart work! After all, it’s a one-time cost providing lifetime benefits too. Use closed cell foam for the basement, wall insulation, etc. Use open-cell for nooks & crannies. Reduce the overall project cost by increasing lifetime durability!

What is better Open-Cell vs Closed-Cell? The Verdict

Anything can be best when it matches your budget and requirement! The best thing is that it doesn’t sag or settle over time. Evaluate everything based on your climate zone, home area, price budget, purpose of insulation, maintenance, durability, efficiency of spray-foam, building-code requirements, and similar.

Closed-cell could be good for colder climates whereas Open-cell could be good for warmer climates. Open-cell is inexpensive but has lower R-value whereas Closed-cell is expensive but has higher R value. It all solely depends on your needs.

Selecting a combination of open-cell and closed-cell could be great! A hybrid combo!

  • Use closed-cell for basement, exterior wall insulation, attic insulation, roof-tops, etc.
  • Use open-cell for awkward gaps, holes, nooks, & crannies.

In a nutshell, go for the Best insulation that Best-suits your Best budget & requirements! Refer to this short post to get answers quickly.