If you’re planning to build a new home or remodel your current residence, you might be considering materials that will help the structure withstand weather conditions while protecting the interior against moisture, water vapor, and air leaks that could cause damages in the long run.

Source: halind.com

Before the siding is installed, a strong, durable material needs to be built-in, and this is where building paper comes in such a scenario. In this article, we’ll provide you with everything you need to know about Grade B building paper to ensure you’re choosing the right product for your building.

What is a Grade B Building Paper?

Building paper, also commonly referred to as a weather-resistant barrier, WRB, or house wrap, is a strong, durable, fibrous paper sheet that is made from Kraft paper. It is constructed from wood pulp and saturated or coated using waterproofing asphalt, which is the same product used to bind aggregate together in asphalt pavement.

Asphalt is a stable black or brown petroleum-based material, which has a consistency ranging from highly viscous, semi-form to glassy solid petroleum.

A building paper is classified into four categories: namely Grade A, Grade B, Grade C, Grade D, and Grade F building paper. 

Grade A building paper is classified as a high water/vapor resistant, self-adhering, and self-sealing material, while Grade C building paper is categorized as non-commercialized, water-resistant material. Grade D building paper is water and vapor permeable, while Grade F building paper is a non-combustible paper material that has been discontinued in use. 

A Grade B building paper, on the other hand, is a weather-resistant barrier classified as moderate water-vapor resistant material. It has a water vapor permeability of a maximum 6 rating, which is measured in grams PSM (per square meter) per 24-hour period, and it has a water resistance measured in hour rating—not less than at least 16 hours.

Grade building papers are rated in the amount of time it ‘wicks’ or how long the moisture-sensitive indicator changes color when a sample looking like a small boat is floated on the water. Common grades of these building papers are 10, 20, 30, and 60 minutes. The higher the grade or rating, the more moisture-resistant and heavier the building paper is.

A common 20-minute building paper weighs about 3.3 pounds per square, a 30-minute building paper weighs 3.75 pounds per square, and a 60-minute building paper weighs about 6 pounds per square.

Uses of Grade B Building Paper

Grade B building paper is commonly used in building construction, acting as a barrier layer or moisture and vapor barrier to protect the building materials by blocking the water, wind, and moisture coming from the outside to penetrate the walls. 

It acts as a cover or drainage layer that allows air or water vapor to exit from the inside while inhibiting exterior water and moisture penetration and keeping the building materials dry, which prevents the growth of mold, mildew, rot, and bugs inside the walls caused by the buildup of moisture.

It’s also commonly used for frame construction, between the exterior wall sheathing and stucco, masonry, brick, vinyl, aluminum, or wood siding, acting as a separation later to prevent stresses created between the two surfaces.

Benefits of Grade B Building Paper

Here are some of the various benefits of using Grade B building paper.

Weather Protection

Grade B building paper provides temporary weather protection of buildings, as it can be used to wrap the structure and cover all types of gaps and cracks between the exterior sheathings and wall surface.

Installing this type of building paper helps reduce the expansion and contraction of wood by preventing the penetration of water through the stucco or masonry surfaces. Since harsh weather conditions can easily damage the structure of the building, using layers of building paper helps reduce the risks of damages like cracks. 

Moisture Control

It also helps provide moderate to better moisture control in residential and commercial applications by preventing water or rain from seeping into the wall while allowing the water vapor to pass through. It strengthens the lifespan of the building because it reduces any threats caused by the build-up of moisture within the cavity walls.

Energy Efficiency and Increased Comfort

Grade B building paper provides better insulation performance for buildings, as it helps control the airflow through the walls of a structure or building.

It also enhances the energy efficiency of the building by inhibiting air drafts from going in and coming out, keeping the humidity and heat out in the summer, and keeping the warm air during colder months, thereby lowering the energy consumption, cooling, and heating costs.

When installed, it also helps keep the indoor air quality good and reduces allergens by acting as a barrier to elements, which enhances the overall comfort inside the building. 


Grade B building papers are also sustainable because most brands are made of recyclable materials. They also provide UV radiation protection, which makes the building safer and helps reduce health risks. 

How Much Does a Grade B Building Paper Cost?

In general, a Grade B building paper costs about $0.41 to $0.97 per square foot and $120 to $300 per roll. The pricing only includes the materials alone. If the materials, labor, and installation costs are included, the pricing of a building paper cost can range from $250 to $990, enough to cover a 2,500-square-foot home. 

The accurate pricing of the building paper may vary, depending on the brand, size, and location of the installation area.

How to Install a Grade B Building Paper

Before installation, make sure you have all the necessary tools and materials, including a hammer stapler, a hammer, a sharp knife, and a roll of building paper.

Make sure you have already cut the building paper with a measurement appropriate to the installation surface size, and you can also cut them into workable sizes. Align the building paper and staple it—ensure to start working from the bottom and work your way up. Make sure the building paper lies flat to the sheathing as well. 

Next is to overlap the pieces—the bottom layer by a minimum of six inches horizontally and vertically on the sill plate to seal the seams and enhance the protection. It’s also good to pull the building paper tight to prevent puckers, creases, and wrinkles. Make sure to avoid tearing the paper while tucking and stapling it.

Once the building is completely covered, use seam tape to seal all penetrations and laps. You can also check for tears and wear, and if there are any, seal it with seam tape and smoothen them to ensure it adheres properly.

Applying Building Paper for Home and Building Construction

Grade B building papers are a great barrier layer alternative for residential and commercial applications as it helps provide weather protection by blocking water vapor, moisture, and air leaks from penetrating the walls of the building. They also keep the building materials dry, which inhibits the growth of damaging elements like rot, mold, mildew, and insects. 

Learning about the uses, benefits, and proper installation of Grade B building paper will help you save money, create a more comfortable environment while reducing energy use. 

Editorial Contributors
Matt Greenfield

Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

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