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Attic Insulation vs Wall Insulation: What’s the Difference?

When most people make a plan to insulate their homes, the attic is the first place they think to install that fluffy pink material.

But did you know that improperly insulated walls can also cost you time, energy, and money in the long run? That’s because walls, like attics, are major components in regulating heat flow in your home. 

For the most cost-efficient, comfortable living environment, it’s best to insulate both your attic and your walls. That said, there are important differences between attic insulation and wall insulation that you should know about.

In this short guide, we’ll cover the important differences are location, type, and R-value requirements.

Location, Location, Location

It may seem obvious that attic insulation is installed in the attic, while wall insulation is installed in the walls. However, given the unique features of both spaces, it’s worth going over their layouts in more detail before you start replacing your existing insulation.

Attic Insulation

In many modern homes, the attic is the large rectangular or square space beneath the roof and above the main living space. The following are the main components of the typical attic:1

  • Rafters
  • Perpendicular joints
  • Sheathing made of plywood

To properly insulate your attic, install new insulation between the attic’s perpendicular joists. You may also want to do an attic insulation installation between wall joists and around windows. 

Walls

Although there are several types of walls, wooden walls are the most common in the modern home. A wooden wall’s layout dictates where insulation should go.

Most wooden walls contain the following:2

  • Top and bottom plates
  • Studs (wall, cripple, and trimmer)
  • Fire blocks

To properly insulate your walls, install home insulation in the spaces between wall studs. You may also need to hand-cut smaller pieces of insulation so that you can insulate small cavities around windows and doors.

Material Type

Given the distinct layouts of attics and walls, you’ll likely need different types of insulation to properly insulate these two spaces. This is because walls are largely uniform in terms of the spacing between studs while attics may feature irregular spacing or obstacles between joists.

Below, we’ve broken down the most common home insulation types for attics and walls.

Attics

As stated above, an attic space is often irregularly spaced. Due to this layout, the following insulation types are most commonly used in attics:

  • Loose-fill – Perfect for small spaces and irregular cavities, loose-fill insulation is constructed from various recycled materials, including fiberglass and plastic. The most common way to install loose-fill insulation is with a hose and blower. The loose-fill installation is simply blown into spaces in need of adequate insulation. However, if you’d like to save money, you can install loose-fill insulation by hand instead of hiring a professional for blown installation.
  • Blanket – When most people think of easily installable insulation for an attic space, they picture blanket insulation. This type of insulation comes in two forms: batts and rolls. Batt insulation is insulation cut into panels, while roll insulation comes in pre-cut rolls. If the space between joists is relatively uniform, blanket insulation can be ideal. However, if the space is irregular or filled with obstacles, blanket insulation may not cover every square inch.

Walls

While blanket and loose-fill insulation can be good for walls, the best insulation for walls is foam board or rigid foam insulation.3

This is because foam board insulation is moisture resistant, making it perfect for basement walls and/or walls exposed to the elements.

Foam board insulation has the following properties:

  • Constructed from various synthetic resins, such as polystyrene
  • Easy to apply with a special adhesive made specifically for foam boards
  • High R-values compared to the material’s thickness

R-Value Requirements

An insulation material’s R-value is a measurement of its ability to regulate heat flow. The higher its R-value, the more efficient the insulation material is at reducing heat flow.

Due to their different properties, attics and walls have different R-value requirements. These requirements largely stem from the home’s location, but, in general, wall R-value ranges are lower than attic R-values.

Let’s take a look at a few R-value ranges for attics based on location:4

  • Zone 3 – Comprising most of the South, Zone 3 homes have attic R-values between R30-R60. 
  • Zone 5 – Homes in Zone 5 are largely located in the West and Mid-Atlantic. They require attic R-values ranging between R38-R60.
  • Zone 7 Constituting the northernmost parts of the contiguous U.S., homes in Zone 7 have attic R-values between R49-R60.

While these three zones have three different sets of insulation R-value requirements for attic spaces, homes in any geographic area can benefit from wall insulation with R-values between R13-R15 for 2X4 walls and R19-21 for 2X6 walls.

Attic Construction: For All Your Insulation Needs

So, which kind of new insulation will make the biggest difference in your air quality and energy bills? Properly insulating your walls and your attic with appropriate material can make all the difference in your comfort and your energy expenditure. 

Instead of stressing over the differences between attic insulation vs wall insulation, let Attic Construction help. 

In addition to providing high-quality services ranging from crawl space cleaning to insulation removal, Attic Construction gives you the knowledge to make the best decisions for your family, home, and wallet.

Get in touch with us today to see how we can insulate your attic and walls the right way. 

 

Sources:

  1. Fine Homebuilding. Open attic storage. https://www.finehomebuilding.com/2001/07/01/open-attic-storage
  2. HomeTips. How Walls Are Built. https://www.hometips.com/how-it-works/interior-wood-wall-paneling.html
  3. Bob Vila. All You Need to Know About Types of Insulation. https://www.bobvila.com/articles/types-of-insulation/
  4. John Manville. What R-value Do I Need? https://www.jm.com/en/homeowner-insulation/homeowner-faq/what-r-value-do-i-need-/

 

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