Is Spray Foam Insulation Waterproof?

When it comes to insulation, most homeowners and builders ask, ‘Is spray foam insulation waterproof?’ This question is important if you are concerned about spray foam insulation’s water-resistant properties and how it affects the effectiveness of insulation.

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In this article, we will discuss the following important aspects of waterproof spray foam insulation:

  • Importance of waterproof insulation.
  • Factors affecting spray foam’s water resistance.
  • How to ensure proper installation of waterproof spray foam insulation.
  • How to find the right waterproof spray foam insulation.

Why is It Important to Have Waterproof Insulation?

Water is one of the major causes of damage in every home. Moisture causes mold growth and mildew in the home, which reduces the structural strength of the building. Additionally, according to research done by, in  2021, floods and flash floods caused over three billion U.S. dollars worth of property and crop damage across the United States. Using waterproof insulation helps to protect your home from moisture damage and also improves energy efficiency. 

Waterproof insulation saves energy costs caused by water seeping through walls, holes, or gaps. Water conducts heat better than air, and when it comes into the building, it causes a faster transfer of heat, leading to high energy consumption. By preventing water from entering the building, waterproof insulation reduces energy consumption. 

Water destroys insulation materials by displacing air trapped in them. By creating a moisture barrier, waterproof insulation maintains the effectiveness of the building’s insulation. Waterproof insulation is vital in areas prone to flooding or high rainfall by maintaining insulation durability and building structure. 

Factors Affecting Spray Foam Insulation's Water Resistance

Spray foam insulation is a reliable waterproofing foam for every building. Spray foam insulation adds that extra layer of protection from moisture in your building. Nevertheless, there are factors that affect spray foam insulation’s water resistance.

Infografik Factors Affecting Spray Foam Insulation's Water Resistance

Type of Foam Used (Open Cell vs. Closed Cell)

Closed-cell spray is more efficient for waterproof insulation because it is denser and offers a tight cell that retards water. The two types of spray foam insulation offer excellent thermally insulating properties, but the closed-cell spray foam is watertight

This article on closed-cell vs. open-cell spray foam explains the peculiar benefits of both types of spray foam insulation. 


The thickness of the insulation is a factor that determines the water resistance properties of spray foam insulation. The thicker the insulation, the more the ability to resist water from seeping through the building. 

Quality of Installation

The quality of installation is important, as proper installation is vital when it comes to spray foam insulation. When spray foam is not installed properly, it can lead to complications affecting its water resistance ability.

Gaps or Voids

Gaps, holes, and voids in the building affect the spray foam’s water resistance ability. As a result, water can seep into the building through these gaps and voids, reducing the effectiveness of spray foam insulation. 

What are the Benefits of Waterproof Spray Foam Insulation?

For maximum comfort, every building needs to be protected from heat and excess moisture all year round. Spray foam insulation is the best waterproof insulation that protects against heat transfer, noise, and moisture. Some of the benefits of waterproof spray foam insulation include the following:

Infografik_What are the Benefits of Waterproof Spray Foam Insulation

Improved Energy Efficiency

Waterproof spray foam insulation improves energy efficiency by maintaining a consistent building temperature. In addition, waterproof spray foam insulation provides excellent thermal resistance by sealing holes, gaps, and crevices that cause building leakages and heat loss. 

Increased Durability

Waterproof spray foam insulation offers more durability than other insulation methods. Spray foam insulation is long-lasting, and it does not shrink over time. Waterproof spray foam insulation maintains the structural integrity of the building. For example, a roof insulated with waterproof spray foam will last longer.

Eliminates Condensation

Condensation in buildings is a result of moisture buildup. Waterproof spray foam insulation helps to eliminate condensation that can lead to mold growth and mildew. Spray foam insulation is one of the most reliable ways to deal with condensation problems in your home.

How to Ensure Proper Installation of Waterproof Spray Foam Insulation?

Proper installation of waterproof foam insulation is essential to its effectiveness. When done right, waterproof spray foam is the right insulation system for any building. However, it can be messy when not properly installed. The following guidelines will help you ensure the proper installation of waterproof spray foam insulation:

Many drops of water on a dark tree

Hire a Professional or DIY

To get the best out of expanding foam insulation, you need the services of a licensed professional. However, you can carry out foam insulation as a DIY project. Licensed professionals have the necessary equipment and training for a successful installation.

Prepare The Surface  

Before installing waterproof spray foam insulation, make sure the surface is dry and clean. Debris, dust, and even moisture should be removed before applying the insulation.

Applying the Insulation

When installing waterproof spray foam, fill all gaps, holes, and voids. In addition, spray foam should cure properly to prevent the release of toxins. 

Ensure Proper Ventilation

Proper ventilation is vital when installing waterproof spray foam to protect you from the release of harmful chemicals. In addition, proper ventilation prevents the accumulation of moisture that can lead to mold growth in the building.

Inspect The Insulation

After installation, the next step is to inspect the insulation to make sure the spray foam is applied correctly. 

Maintain The Insulation

Proper maintenance of insulation is essential to ensure its effectiveness over time. Any damages or deterioration should be checked regularly and repaired or replaced as needed.

How do I Find The Right Spray Foam for Waterproofing? 

The quality of the spray foam used also play a significant role in the effectiveness of waterproof spray foam. Kraken Fast Coat Spray foam is all you need for your waterproof spray foam, and it comes with an R-value of R5.66 per 1-inch thickness. The Fast Coat Product is a closed-cell spray foam suitable for all insulation types, such as roof, garage, wall, or crawl space insulation. For easy DIY spray foam insulation, order the Fast Coat Product now!

KrakenBond Waterproof Fast Coat insulation Can


What type of expanding foam is waterproof?

Closed-cell spray foam is waterproof. It is dense and repels water for an extended amount of time.

Is Open-Cell Spray Foam Insulation Waterproof?

No, open-cell spray foam insulation is not waterproof. Open-cell spray foam insulation absorbs water and has a low density.

Is Closed-Cell Spray Foam Insulation Waterproof?

Yes, closed-cell spray foam insulation is waterproof because of its high density. 

Can spray foam insulation get wet?

Spray foam insulation can get wet, but the type of spray foam installed will determine the extent to which it can deal with moisture. For example, closed-cell spray foam insulation has a higher water resistance than open-cell spray foam.

Does spray foam insulation seal out water?

Closed-cell spray foam insulation can seal out water because it is water impermeable.

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Author : Krakenbond Team

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