How To Install Rigid Foam Insulation On Interior Walls

The insulation in your home keeps you warm in the winter and cool in the summer. Insulation made of rigid foam board can be used throughout the house if you want to install insulation in your home but are unsure how to go about it. Fortunately, we are here to assist you in properly installing the insulation by sharing our research with you.

To properly install your rigid foam insulation on your interior walls, you can follow these simple steps;

  1. Examine the interior walls for any flaws.
  2. Attach the strips
  3. Install the insulation panels
  4. Secure your insulation boards

The steps for installing rigid foam insulation are outlined in this article. We will also go over the various types of rigid foam insulation and their advantages and disadvantages. So continue reading to find out more.

How To Properly Install Rigid Foam Insulation On An Interior Wall? 

Construction worker installing styrofoam insulation sheets and filling space between with expanding foam on house facade wall for thermal protection

In your home, rigid foam insulation acts as a blanket. It increases thermal resistance in your household, lowering your heating bills. You can place it almost anywhere in your home. This also strengthens the structure of your walls, transforming them into a sturdy, energy-efficient component of your home. 

The steps for installing rigid foam insulation are as follows: 

Step 1-Examine The Interior Walls For Any Flaws

Inspect the interior walls before installing rigid foam insulation. Apply waterproof paint to the affected area of the interior walls to resolve any moisture issues. If you believe the issue you discovered while inspecting the interior walls is serious, seek professional assistance.

Step 2-Attach The Strips

Start attaching the furring strips after you have finished inspecting and correcting any moisture problems on your interior wall. Furring strips, which can be made of wood or metal and are specifically designed to support surfaces once installed, can be used.

Attach the furring strips 16 inches apart to the walls using adhesive or a ramset. This type of strip provides a level surface to which you can attach the insulation and any covering drywall or paneling you may want to use.

Since irregularities in the walls are inevitable, you will need to use shim material to level and rectify the irregular walls. Shims are typically thin wood wedges sold for a low price or recycled wood scraps, but they can also be metal. Shimming the furring strips into place levels them.

Click to see Ramset on Amazon.

Step 3-Install The Insulation Panels 

Mark the necessary size on the rigid foam insulation panels. Cut the foam with a knife or a saw, following the mark as a guide. Check that the panels fit snugly against the furring strips that have been installed.

Following that, insert the panel between the strips. Make sure there is no space or gap between the insulation boards as protection for your boards. Fill in any gaps or spaces in the wall with adhesive tape or caulk.

Step 4-Secure Your Insulation Boards

Plastic insulation provides additional protection for rigid foam insulation panels. This keeps water vapor from penetrating the panels and causing additional damage.

When stapling the plastic insulation, be careful not to snag it on the furring strips and perforate it unnecessarily. You can now cover the insulation by attaching the drywall or paneling to the furring strips.

What Are The Different Types Of Rigid Foam Insulation?

There are several types of rigid foam board insulation. Each has its own applications, but professionals will frequently have to choose between them depending on the project or customer requirements. 

Extruded Polystyrene (XPS)

Worker placing XPS polystyrene insulation boards on the flat roof

Extruded polystyrene rigid foam board insulation is the most widely used foam board insulation. It's available in three colors: blue, green, and pink. 

The most recognizable type of rigid foam board insulation is extruded polystyrene foam board, most commonly used in walls and below-grade areas. It comes in a variety of finishes, including various plastic facings and none at all.

Since it does not entirely absorb moisture, XPS does not function as a complete vapor barrier. As a result, the R-value may gradually decrease over time due to moisture absorption. However, this problem is slow and will not be apparent for many years.

One advantage of the XPS rigid foam board is that it is recyclable. As a result, it is a more environmentally friendly option than many other types of insulation.

Click to see Extruded Polystyrene on Amazon.

Expanded Polystyrene (EPS)

Sheet of expanded polystyrene on the concrete floor for house thermal insulation during constructions

For homeowners, EPS foam board insulation is a great option. It is suitable for insulating walls, roofs, floors, and basements. Since EPS is water-resistant and does not absorb, you can use it on the ground and below grade.

EPS acts as a vapor barrier and aids in the prevention of insects and other pests. Furthermore, the R-value does not degrade over time. As a result, its efficiency is the same on the first day it is installed as on the last day it is used.

Contractors commonly use EPS to insulated concrete forms and structural insulated panels. It complies with or exceeds all building and energy codes. However, it is thermoplastic and may degrade at extremely high temperatures.

Click to see Expanded Polystyrene on Amazon.

Polyisocyanurate (Polyiso, ISO)

The polyisocyanurate foam has the highest R-value. This rigid foam typically has a reflective foil facing on both sides, allowing it to function as a radiant barrier. 

Polyiso is not recyclable and has a high permeability. It has a foil vapor barrier on the back and a white foil finish on the front, which provides quality insulation while also giving the space a clean, finished look.

For those worried about safety and the environment, Polyiso's flame retardant is less toxic than those used in other insulations. The disadvantage is that it is the most expensive of the options discussed here. Furthermore, because it absorbs water, it is unsuitable for below-grade applications.

Click to see Polyisocyanurate on Amazon.

What Are The Advantages And Disadvantages Of Rigid Foam Insulation?

Advantages and disadvantages of rigid foam insulation, How To Install Rigid Foam Insulation On Interior Walls

The following are some of the advantages and disadvantages of using rigid foam insulation:

Advantages Of Rigid Foam Insulation

The following are some of the benefits of rigid foam insulation:

Energy Efficiency

Interior wall insulation adds another layer of energy efficiency to your home. Insulated interior walls prevent thermal stress that can break drywall. These insulated rooms will also maintain their temperature for a longer period.

Interior wall insulation can reduce heat transfer and help you save money on your utility bill in rooms that aren't used often, such as guest rooms or storage rooms.

Air Leaks 

Rigid foam insulation creates a continuous seal on your home's exterior, preventing unwanted air leaks that can lead to inefficiencies. 

Additionally, this insulation can prevent air from entering and exiting your home. Most seals prevent only one of these things, but rigid foam insulation prevents both.

Sound Protection

Insulation has many advantages besides providing a barrier between indoor and outdoor temperatures. It also serves as a soundproofing barrier. 

Insulation helps keep sound from traveling through walls that separate apartments or condos. Insulated interior walls are also beneficial in bedrooms that require a quieter setting, such as a nursery.

Moisture Control

While not all rigid foam board insulation can act as a vapor barrier, they all aid in moisture control. They not only keep the interior wood or framing from coming into contact with exterior rain or humidity, but they also keep the interior sheathing warm enough to prevent moisture accumulation.

Disadvantages Of Rigid Foam Insulation

Builder installing rigid styrofoam insulation board for energy saving

Despite all of the benefits, foam board insulation will pose a few difficulties to homeowners. Keep these factors in mind when deciding on the best insulation for your home.

UV Light Sensitivity

UV light, such as sunlight, can damage rigid foam board insulation. However, this is not a problem after installation.

It is essential to store it correctly before installation to avoid damage. Contractors will manage this for you, but it is something you should think about as a homeowner. 


Rigid foam board insulation is generally more expensive than other popular types. As a result, the initial costs of foam board insulation may be relatively high, but the benefits usually outweigh this disadvantage.

There is a positive return on investment if you have the funds to pay for the insulation up front. Lowering utility bills and preventing moisture damage will usually more than offset the initial cost of materials and installation.

Proper Installation Required

The benefits of rigid foam board insulation are negligible unless properly installed. Fortunately, no special equipment is required for installation. However, it would help if you did it correctly.

Furthermore, rigid foam board insulation installation and sealing are governed by building codes. Moisture and air can penetrate the insulation if it is not present. 

Not Very Strong Structurally

Insulation made of rigid foam board adds structural strength. However, it is not as firm as plywood.

Fortunately, you can layer rigid foam boards and wood sheathing to provide insulation and structural stability. If you do not intend to use wood sheathing with your insulation, you will need to find another bracing to help improve the insulation's structural performance. 

It's A Wrap!

Rigid foam board insulation is simple to use and performs a critical function. Installing foam board insulation is a great do-it-yourself project for developing new skills. You need to ensure that your rigid foam insulation is installed properly and correctly to avoid having to rework it and get the most out of its benefits.

If you enjoy this topic, you can check this other article for more information:  

Is Expanding Foam Waterproof, Heat Resistant, & Good For Insulation?

How To Attach Fiberglass Insulation To Concrete Wall

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