Best Insulation For Your Walls

So, your walls need some insulation. Which insulation should you choose? You could opt for something budget-friendly or splurge on a premium insulation product. What is the best choice for your walls?

South Central Services has insulated hundreds of projects in and around Greencastle, PA. The best insulation for your walls will depend on several factors. By the end of this article, you'll know which product is best for your walls.

Exterior Walls vs. Interior Walls: What's The Difference?

Before diving into different insulation products, we must discuss the differences between exterior and interior walls.

You may think that a wall is a wall, but these two types of walls perform vastly different functions for your home.

An exterior wall is part of your thermal envelope. These walls are responsible for managing temperature differences. Exterior walls may also be concerned with soundproofing to avoid neighborhood noise pollution. As a general rule, exterior walls need high-performing insulation.

An interior wall is not part of your thermal envelope. These walls make up the division of rooms in your home. There are no significant temperature differences to manage from room to room. Interior walls are almost always concerned with soundproofing to help offer privacy. Interior walls usually do not need high-performance insulation.

In milder climates, the performance of thermal envelope insulation is less prevalent. You can think of exterior wall insulation like a coat for your house. If you live in a climate where you only need a light jacket in the winter, you might not need high-performance insulation in your walls. However, if you often have to bundle up in the winter months, your exterior walls must "bundle up" too.

Now that we've examined the differences between exterior and interior walls, let's look at insulations individually.

Fiberglass Batt: A Good Sound Barrier For Interior Walls

Fiberglass batt is a budget-friendly insulation product. Batt insulation is widely available and commonly installed as a DIY. One of the biggest strengths of batt insulation is its sound attenuation capabilities. The structure of fiberglass batts helps to muffle and absorb sound waves.

When renovating, fiberglass batt is almost always an affordable option for interior walls. Our team often installs batt insulation in interior walls in new construction homes. Fiberglass batt is a good option if your interior walls can be accessed.

The biggest drawback of fiberglass is its insulating performance. While fiberglass can offer a high R-value initially, this R-value usually drops over time as the insulation settles or sags. This drop in performance is not a significant concern for interior walls, but it can be problematic for exterior walls.

If you are not concerned with the insulation performance of your exterior wall insulation, fiberglass is a reasonable option. However, if your exterior walls need high-performance insulation, there are better choices than fiberglass.

Dense Pack Cellulose: An Option For Interior & Exterior Walls

Dense pack cellulose can work well for both interior and exterior walls. Some insulation contractors will install dense pack in all the walls of a new construction home.

Dense pack delivers better performance than batt insulation while also delivering excellent sound attenuation. Another advantage of dense pack cellulose is its ability to conform to unique cavities. Batt insulation can be a pain to install in nonstandard cavities, but dense pack can easily fill those spaces.

One drawback of dense pack cellulose is its messy, dusty installation process. Dense pack is most commonly installed in new construction homes or homes undergoing significant renovations. You would not want to have dense pack installed in a home where you are also living because the installation would leave your belongings covered in dust.

Another drawback of dense pack cellulose is its cost. Unlike fiberglass batts, dense pack is not as affordable of an insulation option.

Depending on your climate zone and the needs of your exterior walls, dense pack could be an excellent option. Discuss dense pack cellulose with your insulation contractor.

Hybrid System Insulation: For Exterior Walls Under Renovation

Hybrid system insulation tries to deliver the best of both worlds. Fiberglass is incredibly affordable but lacks in performance. Other insulations are high-performing but quite expensive. An ideal option emerges by combining these two categories into a hybrid system.

In a hybrid system, exterior walls receive a layer of high-performance insulation. This could be two inches of closed cell spray foam or dense pack cellulose. Once the thin layer of more expensive insulation is installed, the remainder of the cavity is filled with a more affordable batt.

Hybrid insulation can be an excellent choice when building a new home or renovating an existing one. The cost is usually less than using spray foam or dense pack alone, while the performance is better than just a fiberglass batt.

It is important to note that a qualified insulation contractor must install hybrid insulation. If the layer of high-performance insulation is too thin, the wall could experience problems in certain climate zones. Discuss your wall insulation options with your insulation contractor.

Closed Cell Spray Foam: Best For Below-Grade Walls

When it comes to below-grade walls, closed cell spray foam is the ideal choice. Below-grade refers to any area below the ground. These walls face excessive moisture and cold due to their location. Below-grade walls are also usually composed of concrete blocks or stone, which are porous materials. For below-grade walls, moisture management is critical.

As long as your basement or crawl space walls are not dealing with standing water issues or liquid water leaks, closed cell spray foam is your best option for insulating. Closed cell spray foam offers a vapor barrier at two inches depth. The vapor barrier helps to manage vapor transfer in these areas of the home.

There are many ways to insulate basement walls, depending on how you plan to use your basement. While you could use fiberglass batts or blankets, the safest option is closed cell spray foam. Unfortunately, closed cell is a pricey insulation option. However, opting for closed cell will be best for your home's health and your investment's longevity.

Open Cell Spray Foam: A Great Choice For Above-Grade Walls

For above-grade exterior walls, open cell spray foam is an excellent choice. Above-grade walls are above the ground and have fewer concerns about vapor transfer and moisture management. While exterior walls may still need high-performing insulation, the need for a vapor barrier is less certain.

Open cell spray foam is the less expensive option between open and closed cell spray foam. Depending on the demands of your climate zone and your weather patterns, you may be able to use open cell spray foam in your exterior walls upstairs.

Injection Foam: For Uninsulated Exterior Walls

Sometimes, your walls aren't exposed and ready for insulation. Not everyone can afford to build a brand-new house, and tearing down drywall is expensive. If you aren't already undergoing renovations, you might be unable to prepare your walls for these other insulations.

Injection foam insulation is a product designed to bridge that gap. Exterior walls still need insulation, even if you can't easily expose the walls for insulation. The goal of injection foam is to insulate exterior walls while being minimally invasive.

Unfortunately, injection foam does not consistently deliver on its promises. While insulating an otherwise inaccessible wall is appealing, there are risks associated with filling a wall cavity you can't see inside. When exterior walls already have some insulation, injection foam is not the best choice. This slow-expanding foam may miss a spot or trap moisture and mold inside your walls.

South Central Services only recommends injection foam as an option for exterior walls that never had any insulation before. Older and more historic homes may qualify for injection foam. When the wall cavities are entirely empty, there is less risk of problems with the insulation.

The Bottom Line About Which Insulations Are Best For Walls

The best wall insulation depends on many factors: where the wall is, what climate you live in, and your goals for the insulation. Exterior walls tend to need more performance, which means a product like spray foam or dense pack insulation. Interior walls are more concerned with sound attenuation, making fiberglass batts and dense pack ideal options.

We recommend connecting with a qualified insulation contractor to discuss your options. These specialists can help determine your goals and which insulation best fits your needs and budget.

Now that you understand which insulations are best for walls, your next step is to:

• Weigh the pros and cons of fiberglass in an exterior wall
• Compare hybrid system insulation with flash and batt
• Learn more about the best insulations for new construction