Moisture barriers are essential components in construction, designed to protect buildings from the damaging effects of water infiltration. Whether used in walls, floors, or roofs, these barriers prevent moisture from compromising the structural integrity of buildings, causing mold growth, and deteriorating materials. Understanding the different types of moisture barriers available and their specific applications can help you choose the right solution for your construction needs. This blog provides a comprehensive explanation of various moisture barriers, detailing their characteristics, advantages, and best use cases.

Types of Moisture Barriers

Polyethylene Sheeting

Description: Polyethylene sheeting is a flexible plastic film commonly used as a moisture barrier. It comes in various thicknesses, with thicker sheets offering greater durability and protection.

Advantages: This type of barrier is affordable, easy to install, and widely available. It is effective in preventing moisture vapor from penetrating surfaces.

Best Uses: Polyethylene sheeting is ideal for use under concrete slabs, in crawl spaces, and as a vapor barrier in walls and ceilings.

Asphalt-Saturated Felt

Description: Asphalt-saturated felt, often referred to as tar paper, is made by saturating a base of organic or fiberglass material with asphalt. This creates a durable, water-resistant layer.

Advantages: This barrier is known for its durability and resistance to water. It also allows some breathability, helping to prevent moisture buildup within walls.

Best Uses: Commonly used as an underlayment for roofing and as a moisture barrier in exterior walls, particularly in residential construction.

Building Paper

Description: Building paper is a heavy-duty paper treated with asphalt or tar to provide water resistance. It is similar to asphalt-saturated felt but lighter and more flexible.

Advantages: It provides good moisture resistance while allowing the structure to breathe. Building paper is also easy to work with and install.

Best Uses: Typically used as a moisture barrier in wall assemblies and as an underlayment for siding and roofing materials.

House Wrap

Description: House wrap is a synthetic material, usually made of woven or non-woven polyethylene fibers. It is designed to be both water-resistant and breathable.

Advantages: House wrap effectively prevents water penetration while allowing vapor to escape, reducing the risk of mold and mildew. It is also lightweight and easy to handle.

Best Uses: Widely used as an exterior moisture barrier in residential and commercial buildings, particularly under siding.

Liquid-Applied Barriers

Description: Liquid-applied barriers are coatings that can be brushed, rolled, or sprayed onto surfaces to create a seamless, flexible moisture barrier.

Advantages: These barriers form a continuous, seamless layer that conforms to the surface, filling gaps and cracks. They are highly effective in complex shapes and areas with many penetrations.

Best Uses: Ideal for use on walls, roofs, and foundations, especially in areas with complex geometries or where traditional sheet barriers are difficult to apply.

Self-Adhered Membranes

Description: Self-adhered membranes are rolls of flexible material with an adhesive backing. They are applied directly to surfaces, creating an instant moisture barrier.

Advantages: Easy to apply and form a tight seal, these membranes provide excellent moisture protection and are highly durable. They are also effective in bridging cracks and gaps.

Best Uses: Commonly used in roofing, around windows and doors, and in foundations to prevent moisture penetration.

By understanding the different types of moisture barriers and their specific applications, you can make informed decisions about the best products to use in your construction projects. Each type of barrier offers unique benefits, and selecting the right one ensures effective moisture management, protecting your building from the harmful effects of water infiltration.

Understanding the various types of moisture barriers is essential for selecting the right one for your construction or renovation project. Each type offers unique properties and benefits, making them suitable for different applications. This section focuses on polyethylene sheeting, one of the most common and versatile moisture barriers available.

Polyethylene Sheeting

Description and Characteristics

• Made from Plastic Polyethylene: Polyethylene sheeting is a flexible, plastic film composed of polyethylene, a durable and water-resistant material. It is engineered to provide an effective barrier against moisture.
• Available in Various Thicknesses (Mil Ratings): This sheeting is available in a range of thicknesses, measured in mils (thousandths of an inch). Thicker sheeting offers greater durability and moisture resistance, with common thicknesses ranging from 6 mils to 20 mils.

Benefits

• Cost-Effective and Widely Available: One of the major advantages of polyethylene sheeting is its cost-effectiveness. It is an affordable option that is readily available at most hardware and construction supply stores.
• Easy to Install: Polyethylene sheeting is user-friendly and can be installed with basic tools. Its flexibility allows it to conform to various surfaces, making it easy to handle and apply.
• Provides a Solid Moisture Barrier: This sheeting creates a robust barrier that effectively prevents moisture from penetrating surfaces. It helps to protect structures from water damage, mold, and mildew.

Applications

• Crawl Spaces: Polyethylene sheeting is commonly used in crawl spaces to create a vapor barrier that prevents ground moisture from rising into the structure. It helps to maintain a dry environment, reducing the risk of mold and structural damage.
• Basements: In basements, polyethylene sheeting can be applied to walls and floors to prevent moisture infiltration. This is particularly important in below-grade areas where water seepage is more likely.
• Under Concrete Slabs: When constructing concrete slabs, polyethylene sheeting is often laid beneath the concrete to act as a vapor barrier. This prevents moisture from the ground from wicking up into the slab, which can lead to cracking, efflorescence, and other issues.

Polyethylene sheeting is a versatile and reliable moisture barrier that can be used in a variety of applications. Its affordability, ease of installation, and effective moisture protection make it an excellent choice for many construction and renovation projects. By selecting the appropriate thickness and ensuring proper installation, polyethylene sheeting can provide long-lasting protection against moisture and help maintain the integrity of your building.



Understanding the different types of moisture barriers is crucial for ensuring effective moisture control in various construction projects. Each type has unique characteristics, benefits, and applications. Here’s a comprehensive guide to some of the most commonly used moisture barriers.

Polyethylene Sheeting

Description and Characteristics:

• Made from Plastic Polyethylene: This flexible plastic film is made from polyethylene, known for its durability and water resistance.
• Available in Various Thicknesses (Mil Ratings): Thicknesses range from 6 mils to 20 mils, with thicker sheets offering greater durability and moisture resistance.

Benefits:

• Cost-Effective and Widely Available: Polyethylene sheeting is affordable and readily available at most hardware and construction supply stores.
• Easy to Install: It is user-friendly and can be installed with basic tools, conforming easily to various surfaces.
• Provides a Solid Moisture Barrier: Creates a robust barrier that effectively prevents moisture from penetrating surfaces.

Applications:

• Crawl Spaces: Used to prevent ground moisture from rising into the structure.
• Basements: Applied to walls and floors to prevent moisture infiltration in below-grade areas.
• Under Concrete Slabs: Acts as a vapor barrier to prevent ground moisture from wicking up into the slab.

Liquid-Applied Moisture Barriers

Description and Characteristics:

• Applied as a Liquid and Dries to Form a Solid Barrier: These barriers are applied in liquid form and dry to create a seamless, solid barrier.
• Types Include Asphalt Emulsions, Latex, and Rubber-Based Coatings: Various formulations are available to suit different application needs.

Benefits:

• Seamless Application: Forms a continuous barrier without seams, reducing potential leak points.
• Excellent Adhesion to Various Surfaces: Adheres well to a wide range of substrates, ensuring durability.
• Suitable for Complex Shapes and Penetrations: Ideal for areas with many penetrations or irregular shapes.

Applications:

• Foundations: Protects against moisture intrusion at the base of the structure.
• Roofs: Used to seal and waterproof roof surfaces.
• Exterior Walls: Applied to exterior walls to prevent water infiltration.

Foam and Foil-Backed Barriers

Description and Characteristics:

• Comprised of Foam Insulation with a Foil Backing: Combines foam insulation with a reflective foil surface.
• Reflective Surface Helps in Thermal Insulation: Enhances thermal insulation by reflecting radiant heat.

Benefits:

• Provides Both Moisture and Thermal Barrier: Offers moisture protection while also improving energy efficiency.
• Easy to Handle and Install: Lightweight and easy to cut and fit into place.
• Suitable for Retrofitting: Ideal for adding insulation and moisture protection to existing structures.

Applications:

• Attics: Used to improve insulation and moisture protection in attic spaces.
• Roofs: Installed under roofing materials to provide additional insulation and moisture protection.
• Walls: Used in wall assemblies to enhance thermal and moisture performance.

Asphalt-Coated Paper

Description and Characteristics:

• Paper Material Coated with Asphalt for Waterproofing: Known as roofing felt or tar paper, it provides waterproofing by combining paper with an asphalt coating.
• Commonly Known as Roofing Felt or Tar Paper: A traditional material used in many roofing applications.

Benefits:

• Durable and Water-Resistant: Offers strong resistance to water penetration.
• Provides Additional Protection for Roofing Systems: Acts as an extra layer of defense under shingles or other roofing materials.
• Inexpensive and Easy to Use: Cost-effective and simple to install.

Applications:

• Roof Decks: Installed under shingles to provide a moisture barrier.
• Under Siding: Used behind siding materials to prevent moisture infiltration.
• Floors: Applied as an underlayment in certain flooring applications.

House Wrap

Description and Characteristics:

• Synthetic Material, Typically Made from Polyethylene or Polypropylene Fibers: A breathable, flexible material designed for exterior use.
• Breathable, Allowing Moisture Vapor to Escape While Keeping Liquid Water Out: Balances moisture control and ventilation.

Benefits:

• Enhances Energy Efficiency: Helps maintain consistent indoor temperatures by reducing air leakage.
• Protects Against Wind and Water: Provides a barrier against external elements while allowing the building to breathe.
• Easy to Install: Lightweight and easy to cut, making installation straightforward.

Applications:

• Exterior Walls: Commonly used under siding to protect the building envelope.
• Under Siding: Installed beneath various types of siding to provide an additional moisture barrier.

By understanding these different types of moisture barriers, their benefits, and appropriate applications, you can make informed decisions to protect your building from moisture-related issues. Each type offers unique properties that make it suitable for specific uses, ensuring optimal performance and longevity for your construction project.



Selecting the right moisture barrier is crucial for protecting your building from moisture-related damage. The choice depends on several factors, including the type of project, climate conditions, and compatibility with building materials. This guide will help you navigate the key considerations when choosing a moisture barrier for your construction or renovation project.

Project Type and Location

Residential vs. Commercial Projects:

• Residential Projects: In residential construction, moisture barriers are often used to protect areas like basements, crawl spaces, and exterior walls. Polyethylene sheeting and house wrap are commonly used in these settings due to their cost-effectiveness and ease of installation.
• Commercial Projects: Commercial buildings may require more robust moisture barriers, such as liquid-applied barriers or self-adhered membranes, to withstand higher traffic and more demanding environmental conditions. The scale and complexity of commercial projects often necessitate durable and long-lasting solutions.

Indoor vs. Outdoor Applications:

• Indoor Applications: For indoor moisture control, particularly in basements or beneath concrete slabs, polyethylene sheeting is a popular choice. It effectively prevents ground moisture from penetrating the structure.



• Outdoor Applications: Exterior applications, such as protecting walls, roofs, and foundations, often require more resilient materials like house wrap, asphalt-coated paper, or liquid-applied barriers. These materials are designed to handle exposure to the elements and provide long-term protection.

Climate and Environmental Conditions

Humidity Levels:

• High Humidity Areas: In regions with high humidity, it is crucial to select moisture barriers that can effectively prevent moisture vapor from infiltrating the building. House wraps and liquid-applied barriers are excellent choices for such conditions due to their breathability and moisture resistance.
• Low Humidity Areas: In drier climates, moisture barriers still play a vital role in preventing occasional rain or snow from causing damage. However, the primary focus may be on barriers that offer ease of installation and cost-efficiency.

Temperature Variations:

• Extreme Temperatures: Areas with significant temperature fluctuations require moisture barriers that can expand and contract without losing effectiveness. Foam and foil-backed barriers and certain liquid-applied membranes are designed to handle these conditions.
• Moderate Temperatures: In regions with stable temperatures, most types of moisture barriers can perform effectively. The choice may then depend more on other factors such as ease of installation and cost.

Exposure to Elements (e.g., Rain, Snow):

• Heavy Rain or Snow: Buildings in areas prone to heavy rain or snow need robust moisture barriers like asphalt-coated paper or high-quality house wraps to prevent water intrusion and protect the structural integrity.
• Mild Weather: In regions with mild weather, lighter materials such as polyethylene sheeting may suffice, provided they are correctly installed and maintained.

Building Materials and Structures

Compatibility with Existing Materials:

• Material Compatibility: It is crucial to choose moisture barriers that are compatible with the existing building materials. For example, asphalt-coated paper works well with wooden structures, while liquid-applied barriers may be more suitable for masonry or concrete.
• Adhesion and Integration: Ensure that the chosen moisture barrier adheres well to the surfaces and integrates seamlessly with other materials used in the construction. This prevents gaps and weak points that could allow moisture penetration.

Impact on Structural Integrity:

• Structural Considerations: The moisture barrier should not compromise the structural integrity of the building. Lightweight materials like house wrap are ideal for walls and siding because they add minimal weight.
• Load-Bearing Surfaces: For load-bearing surfaces like foundations and concrete slabs, thicker and more durable barriers such as polyethylene sheeting or liquid-applied barriers are necessary to provide adequate protection without affecting the structural performance.

By considering these factors—project type and location, climate and environmental conditions, and building materials and structures—you can select the most appropriate moisture barrier for your needs. This ensures that your building is well-protected from moisture-related damage, contributing to its durability and longevity.

When installing moisture barriers, avoiding common mistakes is crucial to ensure their effectiveness and longevity. Proper installation, selecting the right materials, and considering climate conditions are key factors in achieving optimal moisture protection. This section highlights some of the most common mistakes and provides guidance on how to avoid them.

Incorrect Installation

Importance of Following Manufacturer Instructions:

• Adhering to Guidelines: Each type of moisture barrier comes with specific installation guidelines provided by the manufacturer. These instructions are designed to ensure that the barrier performs as intended. Ignoring these guidelines can lead to improper installation, reducing the barrier’s effectiveness.
• Step-by-Step Process: Carefully follow each step outlined in the instructions, from surface preparation to final sealing. Ensure that all recommended tools and materials are used as specified.

Common Pitfalls and How to Avoid Them:

• Inadequate Surface Preparation: Failing to clean and smooth the surface before installation can prevent the barrier from adhering properly. Always ensure the surface is dry, clean, and free of debris.
• Improper Sealing: Gaps and overlaps in the barrier should be sealed thoroughly with appropriate caulk, sealant, or tape. Skipping this step can allow moisture to penetrate.
• Insufficient Overlaps: Overlaps between sheets of moisture barrier should be adequate, typically 6-12 inches, to prevent gaps. Ensure overlaps are securely taped or sealed to create a continuous barrier.
• Incorrect Fastening: Using the wrong type or insufficient number of fasteners can lead to the barrier becoming loose or torn. Follow the manufacturer’s recommendations for the type and spacing of fasteners.

Using Inappropriate Materials

Risks of Selecting the Wrong Type of Barrier:

• Ineffectiveness: Choosing a barrier that is not suited for the specific application can render it ineffective. For example, using a barrier designed for indoor use on exterior walls may not provide adequate protection.
• Damage to Building Materials: Incompatible materials can interact negatively with other building components, leading to damage or reduced performance. For instance, some barriers may trap moisture against wooden surfaces, causing rot.

Ensuring Material Compatibility with the Project:

• Assess Requirements: Evaluate the specific needs of your project, such as the type of construction, location, and environmental conditions. Select a moisture barrier that meets these requirements.
• Consult Experts: If unsure, consult with professionals or manufacturers to determine the best material for your project. Compatibility charts and technical support can help in making an informed decision.

Overlooking Climate Considerations

Impact of Local Climate on Barrier Effectiveness:

• Humidity and Temperature: Local climate conditions, including humidity levels and temperature variations, significantly impact the performance of moisture barriers. High humidity requires barriers that can effectively block moisture vapor, while extreme temperatures demand materials that can expand and contract without degrading.
• Exposure to Elements: Areas with heavy rainfall, snow, or wind require more robust and weather-resistant barriers. Failing to account for these factors can lead to premature failure of the moisture barrier.

Tips for Choosing Climate-Appropriate Barriers:

• Research Local Conditions: Understand the climate and environmental conditions specific to your area. This includes average rainfall, humidity levels, temperature fluctuations, and wind exposure.
• Select Suitable Materials: Choose moisture barriers that are designed to perform well under your local climate conditions. For example, house wraps are ideal for areas with moderate weather, while liquid-applied barriers are suitable for regions with severe weather conditions.
• Consider Long-Term Performance: Opt for materials that offer long-term durability and resilience against the local climate. This ensures ongoing protection and reduces the need for frequent maintenance or replacement.

By avoiding these common mistakes—incorrect installation, using inappropriate materials, and overlooking climate considerations—you can ensure that your moisture barrier performs effectively, providing robust protection for your building. Proper installation, material selection, and climate awareness are key to achieving a durable and reliable moisture barrier system.



Selecting the right moisture barrier for your construction or renovation project is essential to ensure effective moisture control and protect your building from damage. Various factors need to be considered, including the type of project, climate conditions, and compatibility with building materials. This guide will help you understand these critical factors and make informed decisions for your moisture barrier needs.

Project Type and Location

Residential vs. Commercial Projects:

• Residential Projects: In residential construction, moisture barriers are commonly used to protect basements, crawl spaces, and exterior walls. For these applications, materials like polyethylene sheeting and house wraps are often preferred due to their affordability and ease of installation. Residential projects may not require the same level of durability as commercial projects but still need effective moisture protection to prevent mold and structural damage.
• Commercial Projects: Commercial buildings typically demand more robust and long-lasting moisture barriers to handle higher traffic, larger spaces, and more stringent building codes. Materials such as liquid-applied barriers or self-adhered membranes are often used in commercial settings due to their superior performance and durability. These projects may also involve more complex installations requiring professional expertise.

Indoor vs. Outdoor Applications:

• Indoor Applications: Moisture barriers used indoors, such as in basements or under concrete slabs, must effectively prevent ground moisture from penetrating the interior. Polyethylene sheeting is a popular choice for these applications due to its cost-effectiveness and ease of use.
• Outdoor Applications: Exterior applications, including protecting walls, roofs, and foundations, require more resilient materials that can withstand exposure to the elements. House wraps, asphalt-coated paper, and liquid-applied barriers are suitable for these conditions, providing long-term protection against water infiltration and weather-related damage.

Climate and Environmental Conditions

Humidity Levels:

• High Humidity Areas: In regions with high humidity, it is crucial to select moisture barriers that can effectively prevent moisture vapor from infiltrating the building. House wraps and liquid-applied barriers are excellent choices for such conditions due to their breathability and moisture resistance. These barriers help to prevent mold growth and structural deterioration caused by excessive moisture.
• Low Humidity Areas: In drier climates, moisture barriers still play a vital role in preventing occasional rain or snow from causing damage. However, the primary focus may be on barriers that offer ease of installation and cost-efficiency. Polyethylene sheeting may be sufficient in these environments, provided it is installed correctly and maintained.

Temperature Variations:

• Extreme Temperatures: Areas with significant temperature fluctuations require moisture barriers that can expand and contract without losing effectiveness. Foam and foil-backed barriers and certain liquid-applied membranes are designed to handle these conditions, maintaining their protective properties despite changes in temperature.
• Moderate Temperatures: In regions with stable temperatures, most types of moisture barriers can perform effectively. The choice may then depend more on other factors such as ease of installation and cost, rather than specific performance requirements.

Exposure to Elements (e.g., Rain, Snow):

• Heavy Rain or Snow: Buildings in areas prone to heavy rain or snow need robust moisture barriers like asphalt-coated paper or high-quality house wraps to prevent water intrusion and protect the structural integrity. These barriers are designed to withstand prolonged exposure to moisture and provide a durable solution for harsh weather conditions.
• Mild Weather: In regions with mild weather, lighter materials such as polyethylene sheeting may suffice, provided they are correctly installed and maintained. These barriers offer adequate protection in less demanding environments and are typically more cost-effective.

Building Materials and Structures

Compatibility with Existing Materials:

• Material Compatibility: It is crucial to choose moisture barriers that are compatible with the existing building materials. For example, asphalt-coated paper works well with wooden structures, while liquid-applied barriers may be more suitable for masonry or concrete. Ensuring compatibility helps to prevent any adverse reactions between materials that could compromise the effectiveness of the barrier.
• Adhesion and Integration: Ensure that the chosen moisture barrier adheres well to the surfaces and integrates seamlessly with other materials used in the construction. This prevents gaps and weak points that could allow moisture penetration, maintaining the overall integrity of the moisture barrier system.

Impact on Structural Integrity:

• Structural Considerations: The moisture barrier should not compromise the structural integrity of the building. Lightweight materials like house wrap are ideal for walls and siding because they add minimal weight and do not affect the structural load. These barriers are easy to handle and install, making them suitable for various applications.
• Load-Bearing Surfaces: For load-bearing surfaces like foundations and concrete slabs, thicker and more durable barriers such as polyethylene sheeting or liquid-applied barriers are necessary to provide adequate protection without affecting the structural performance. These materials offer enhanced durability and strength, essential for maintaining the stability of load-bearing elements.

By considering these factors—project type and location, climate and environmental conditions, and building materials and structures—you can select the most appropriate moisture barrier for your needs. This ensures that your building is well-protected from moisture-related damage, contributing to its durability and longevity.