Which Type Of Spray Foam Insulation Is Best?

If you want to use spray foam insulation for your project, you want to choose the right kind. But how many kinds of spray foam are there? Is one type of spray foam insulation better than another?

South Central Services has insulated hundreds of projects with spray foam insulation. Our team installs closed cell spray foam, open cell spray foam, and even pour foams. The truth is that which spray foam insulation is best for your project depends on several factors. We are well-versed in these considerations and discuss product options with every customer.

In this article, we'll examine these factors and the different types of foam. By the time you finish reading, you'll know which foam is best for your situation. Specifically, you will learn:

• What types of spray foam insulation exist
• Factors influencing which spray foam to choose
• Which spray foam insulation is best for you

Spray Foam Insulation Has Two Variations

There are two types of spray foam insulation: open cell and closed cell. The main difference between open cell spray foam and closed cell spray foam comes from the cellular structure of the foams.

These cellular differences determine the properties of the foams. Because of its cell structure, closed cell spray foam is more versatile than open cell spray foam. This does not mean that closed cell is the best type of spray foam. Rather, this means that closed cell is sometimes the better, or only, spray foam option due to its features.

Let's examine the differences between open cell and closed cell spray foam in more detail.

Closed Cell Spray Foam

Closed cell gets its name from its cellular structure. If you look at closed cell spray foam on the cellular level, you can see cells tightly packed together.

Because of its densely packed cell structure, closed cell spray foam does not expand to great depths, can create a vapor barrier, and can add some structural backing due to its density. At approximately an inch of depth, closed cell can also create an airtight seal.

Open Cell Spray Foam

Like closed cell, open cell spray foam is also named by its cellular structure. On a cellular level, open cell has loose cells of varying sizes, which are not condensed together.

This cell structure means that open cell spray foam expands more than closed cell. Open cell can also absorb and dampen some sound waves. However, it is less dense than closed cell and cannot create a vapor barrier. At approximately 3.5 inches of depth, open cell creates an airtight seal.

Factors Influencing Which Spray Foam You Should Choose

It would be foolish for contractors to recommend a particular insulation product without any details. Insulation does not exist or function inside a vacuum.

Insulation is a necessary component of a comfortable and energy-efficient building. Buildings are constructed in different climate zones and house people with varying budgets.

To determine which type of spray foam is best for you, ask yourself these questions:

• What's the climate and weather like where I live?
• How much can I afford to invest in premium insulation?
• Which areas of my home am I planning to insulate?

Your answers to the questions above will determine if you must use closed cell spray foam, or if open cell spray foam is a better option.

Let's walk through these questions together.

Consider Your Geography & Climate Zone

South Central Services operates in Climate Zone 5. Specifically, we service counties in southern Pennsylvania, Maryland, Virginia, and West Virginia.

Climate Zone 5 can be described as a colder northern climate. We have distinct seasons and weather patterns depending on the time of year. While we may complain about the dry summer heat in the dead of July, our summers are very different from the humid ones experienced further south.

Your climate zone will influence how your insulation needs to function.

Our recommendations are in the context of Climate Zone 5. If you live in a different climate, your insulation will have different goals to accomplish. For example, our geography requires careful attention to vapor barriers and how they function. Contractors in other states may not need to consider vapor barriers due to their weather patterns.

Consider The Type Of Project You're Completing

Even in our climate zone, our recommended insulation product will change based on what our customer wants to accomplish.

A homeowner trying to boost energy efficiency in their historic home will receive a different recommendation than someone building a new house. Even if we recommend the same product to both customers, the reasoning for using that product varies with the project.

There are several considerations related to the type of project you're completing, such as:

1. Is my project above or below the ground?
2. Is my project easy to access for spraying?
3. What type of surface will the foam will adhere to?

Your answers to these questions can determine which types of spray foam are available for your project, let alone if one is better than the other.

Let's dive into how these details impact the type of spray foam you choose. 

1. Above-Grade vs. Below-Grade

Projects are either above-grade or below-grade. While we may not always label or lead with this description, an insulation project will always fall into one of these two categories.

Above-grade projects are above the ground. Anything on your ground floor level or above fits this description.

Below-grade projects are below the ground. When your project surface is surrounded by dirt and soil, the project is considered below-grade.

Above-grade projects can have either closed cell or open cell spray foam insulation. Below-grade projects, on the other hand, can only have closed cell spray foam. When the moisture content of the ground influences your insulating surface, vapor barriers become vital. Closed cell spray foam can act as a vapor barrier, but open cell spray foam cannot.

If your project is below the ground, the best spray foam insulation to use is closed cell spray foam.

2. Accessibility

When you build a new house, you can put plenty of insulation inside your walls. Before installing drywall, the house is a blank canvas for whatever insulation product you want. After the project is finished, changing the insulation would require demolishing your walls.

There are a few areas in a house that contractors can access for insulation without demolition. Attics, basements, and crawl spaces are the three places you can insulate with relative ease.

For areas in your home that are easily accessible, spray foam insulation can be the best choice for you. Would the project you have in mind would require demolition to create accessibility? If so, spray foam is only an ideal product if you are willing to create that accessibility.

If you want to insulate the exterior walls of your current home, spray foam insulation is not the product you need. Consider a less-invasive insulation like injection foam. However, we can only recommend injection foam if your walls have no existing insulation.

3. Type Of Substrate

In our climate zone, open cell spray foam has limited applications. Open cell is not only reserved for above-grade projects but is also only suitable for some substrates. The substrate is the surface against which spray foam is sprayed.

For Climate Zone 5, open cell spray foam is only installed against wood or a layer of closed cell spray foam. The properties of open cell foam will not allow it to adhere and perform well on some substrates in our climate.

There are situations where open cell spray foam could be installed against metal, but those are the exception, not the rule.

Meanwhile, closed cell spray foam can adhere to wood, metal, masonry, concrete, and brick. Depending on where you are located and what material you are spraying, closed cell is more likely to be the better spray foam insulation.

If you are not insulating against wood, the best spray foam insulation is most likely closed cell. Verify what substrates are suitable for open cell and closed cell spray foam in your climate zone.

Consider Your Budget

So far, you have addressed how where you live and what you plan on insulating will affect your choice between open cell and closed cell spray foam.

At this point, you fall into one of two categories.

1. You must use closed cell spray foam due to climate, project location, or substrate.
2. You could use open cell or closed cell for your project and don't know which is better.

If you fall into the second category, since your situation allows for closed or open cell spray foam, this final factor can help determine which spray foam is best for you.

For readers whose project can use either closed cell or open cell spray foam, the best spray foam insulation is open cell spray foam. Of the two options, open cell foam is cheaper to install.

Open cell does not have as many features as closed cell spray foam. However, we have established that your project does not need those features. If you want to save money on your insulation project, choosing open cell spray foam could cut approximately 30% of your material costs.

Why is open cell spray foam cheaper? The primary reason is due to yield. Starting with the same amount of raw materials will result in more open cell foam as a finished product compared to closed cell.

Our Spray Foam Recommendations For Climate Zone 5 Projects

This section will address common insulation projects and which spray foam insulation we recommend based on our climate zone.

If you live outside of Climate Zone 5, connect with a spray foam insulation contractor in your area who can recommend products based on your weather and climate.

For Attics In Climate Zone 5, We Recommend Open Cell Spray Foam.

You can still insulate your attic with closed cell spray foam. However, if you are looking to save some money on your project, open cell spray foam is the choice product for attics. You will receive all of the necessary and premium benefits of spray foam insulation at the lowest possible cost.

For Basements In Climate Zone 5, We Recommend Closed Cell Spray Foam.

Basements walls are below-grade areas of the home. As such, the only insulation product we can recommend is closed cell spray foam. Closed cell spray foam has vapor barrier capabilities to help manage vapor and moisture content in your basement.

For Crawl Spaces In Climate Zone 5, We Recommend Encapsulation.

Crawl spaces are also below-grade areas of the home, meaning the best–and only–option for insulation is closed cell spray foam. For homeowners in our service area, we recommend encapsulation for crawl spaces.

The encapsulation method includes closed cell spray foam and a thick plastic vapor barrier. These two materials are joined and sealed to create temperature and moisture-controlled space.

Many homeowners have a cramped space somewhere else in their home that is located above-grade. While you may refer to this as a crawl space, it functions differently than a below-grade crawl space. For these spaces, either spray foam is available. Like with attics, you may choose open cell spray foam to save some money on insulating.

The Bottom Line About The Best Spray Foam Insulation

Closed cell spray foam is a more versatile insulation than open cell spray foam. However, the best spray foam insulation is relative to your situation and project. Your budget, climate zone, and project details will all influence which spray foam insulation is best for you.

If you live in Climate Zone 5, we generally recommend open cell for above-grade applications and closed cell for below-grade ones.

Now that you know which type of spray foam is best for you, your next step is to:

• Estimate the cost of spray foam for your attic, basement, or crawl space
• Compare DIY and professional spray foam insulation
• Learn when not to use spray foam insulation