Is 2 Inches Of Closed Cell Spray Foam Enough?

Spray foam insulation is one of the best insulation products available. Spray foam offers high performance that lasts. However, spray foam is also quite expensive to invest in. You may have heard that two inches of closed cell spray foam will be enough. If true, you could save a lot of money on your investment. But will two inches of closed cell really deliver the performance you need?

South Central Services has insulated hundreds of projects in southern PA and areas of Maryland, Virginia, and West Virginia. The truth is that two inches of closed cell isn't always enough insulation. This article will dive into why.

By the end of this article, you will understand:

• The idea behind two inches of closed cell
• Where two inches of closed cell is usually enough
• Why you may need more than two inches of closed cell

Don't have time to read right now? Check out everything you need to know at a glance.

The Right Amount Of Insulation Depends On Several Variables.

Blanket statements about insulation are usually false. Even when we make claims about insulation on our website, we often include disclaimers about climate zones. We also prescribe insulation solutions based on solving a problem.

A universal claim that two inches of closed cell spray foam is enough neglects the variables that influence our homes.

Two inches of closed cell spray foam might be enough insulation for some applications. However, for other applications, only two inches will not be able to deliver the results you need.

So, what are these variables that influence the right amount of insulation? Here's a preview.

1. Climate zone
2. Usage of space

Let’s break down each of these in more detail.

1. Climate Zone Determines Your Insulation Needs.

South Central Services operates out of southern Pennsylvania. We insulate homes and commercial buildings in Climate Zone 5. We are well-versed in the building science rules for our climate zone.

However, driving further south into a warmer climate can change those rules. Different climate zones have different R-value requirements and weather patterns.

In southern PA, our winter days can reach well below freezing. We also have humid summer heat that surpasses 100 degrees Fahrenheit. In the more extreme seasons, there are huge differences in the temperature outside and the thermostat temperature.

Some sources will claim that 2 inches of closed cell spray foam is enough for any application. These sources include charts showing the insulation's efficiency essentially maxing out at 2 inches. However, these charts fail to account for a dynamic Delta T or change in temperature.

These charts assume that the temperature difference between the outside and inside of a home stays constant throughout the year. However, anyone living in a climate like Climate Zone 5 experiences wildly different temperatures depending on the season.

While two inches of closed cell foam might be enough on a mild spring day, it cannot stop heat from pressing into your home during a July heat wave.

Some climate zones with more consistent temperatures may have fewer concerns regarding Delta T. However, for our customers, Delta T dramatically impacts the amount of insulation an area in your home will require.

2. How You Plan To Use Your Space Changes Your Insulation Needs.

Only some homeowners we work with are looking to maximize their home comfort. Sometimes, we insulate a garage or workshop with the goal of making it moderately more temperate.

When you install insulation, your goals have to be kept in mind. Insulation is not just a product that you stuff into your walls. Ideally, insulation is solving a problem. High energy bills, inconsistent temperatures, poor air quality, and cold drafts are all examples of issues you may want to solve.

If you're researching the effectiveness of two inches of closed cell spray foam, you likely want two things.

1. Lower energy costs
2. Maximized comfort

After all, if you can achieve the same amount of performance with less insulation, why wouldn't you save your money?

However, if your goal is to lower your energy costs and be more comfortable in your home, two inches of closed cell might not cut it. Depending on the area of your home and your climate zone, you may need more. Otherwise, you are insulating to solve your problem for certain parts of the year.

In Some Applications, 2 Inches Of Closed Cell Isn’t Enough.

How can you know when two inches of closed cell spray foam will solve your problem? Once you've considered your climate zone and goals, you can examine where you plan to insulate.

In our climate zone, Climate Zone 5, two inches of closed cell is often enough for basements, crawl spaces, exterior walls, and metal buildings. Basements and crawl spaces are both below-grade, so they don't experience significant shifts in Delta T throughout the year. However, these areas could receive up to four inches of foam, depending on other factors unique to your project.

Two inches of closed cell is not enough for an attic. Attics are above-grade spaces. The Delta T that attics experience fluctuates throughout the year. Especially in summer, attics take on a lot of heat. Without insulation, an attic could quickly reach 140 degrees Fahrenheit in our climate zone.

Since the Delta T is higher during some parts of the year, attics need more closed cell spray foam.

The Bottom Line About How Much Insulation You Really Need

Many online experts claim that two inches of closed cell spray foam is enough for any project. These experts present data and charts to demonstrate the efficiency of insulation reaching a reasonable high at two inches. However, these charts assume that the difference between your thermostat and the weather outside is constant all year long.

Whether or not two inches of closed cell is enough for your project is a more complex question. You have to consider your climate zone, weather patterns, and your goals. If you want your home to stay comfortable year round, then the greatest Delta T will factor into how much insulation you need. If the project is an attic, you will need more than two inches of foam in our climate zone.

Now that you understand why the question of how much insulation is more complex, your next step is to:

• Estimate the cost of spray foam insulation for a home project
• Learn whether or not spray foam can really make a home more comfortable
• Discover why homeowners trust South Central Services for their insulation solution