Grade B Building Paper: Everything You Need to Know

Building paper is an essential component in construction, providing vital protection against moisture while allowing structures to breathe. Understanding the various types of building paper and their specific applications can significantly enhance the durability and efficiency of construction projects. In this guide, we will explore the different types of building paper, their uses, technical features, and much more to help you make informed decisions for your home improvement projects.

Comparison of Types and Applications of Building Paper

Type of Building Paper	Application	Features
Grade D Building Paper	Underlayment for roofs and walls	Cost-effective, moisture-resistant
Asphalt-Saturated Kraft	Walls under various siding materials	Breathable, sheds water, high durability
Two-Ply Building Paper	Heavy-duty applications, high moisture areas	Superior strength, long-lasting protection
Vapor Barrier Paper	Under concrete slabs and in crawl spaces	Prevents moisture transfer, high density
Reinforced Bitumen Paper	Flat roofing and temporary protection	Excellent waterproofing, UV resistant

Understanding Building Paper

Building paper is typically made from asphalt-saturated kraft paper, designed to act as a weather-resistant barrier (WRB). Its primary function is to shed water while allowing water vapor to escape, which is crucial in preventing mold and structural damage. According to HAL, building paper is effective when applied in single or double ply configurations, particularly in exterior wall applications beneath various types of siding, including wood, stucco, brick, and vinyl (source: www.halind.com).

Types of Building Paper

1. Grade D Building Paper

Grade D building paper is commonly used as an underlayment for roofs and walls. It is a cost-effective option that provides moisture resistance, making it suitable for a variety of construction projects. While it does not offer the same level of durability as higher-grade options, it serves well for basic applications.

2. Asphalt-Saturated Kraft Paper

This type of building paper is designed to be breathable, allowing moisture vapor to escape while preventing water infiltration. It is ideal for use in exterior walls and is compatible with materials like wood siding and stucco. Its durability and moisture resistance make it a popular choice among contractors.

3. Two-Ply Building Paper

For more demanding applications, two-ply building paper offers enhanced strength and moisture resistance. It is particularly effective in areas that experience high moisture levels, providing long-lasting protection against the elements. This type is recommended for use in heavy-duty construction projects.

4. Vapor Barrier Paper

Vapor barrier paper is essential in preventing moisture transfer in areas such as crawl spaces and beneath concrete slabs. Its high density makes it effective in blocking water vapor, which helps preserve the integrity of structures and prevent mold growth.

5. Reinforced Bitumen Paper

Reinforced bitumen paper is predominantly used in flat roofing applications and as temporary protection during construction. It is known for its excellent waterproofing capabilities and resistance to UV radiation, making it suitable for outdoor use.

Applications of Building Paper

Building paper is versatile and can be used in numerous applications, including:

• Underlayment: Provides a moisture barrier beneath roofing materials and siding.
• Vapor Barrier: Used in crawl spaces and under concrete slabs to prevent moisture penetration.
• Temporary Protection: Shields structures from the elements during construction.
• Insulation Underlay: Acts as a vapor check in insulated wall cavities.

Technical Features of Building Paper

Feature	Grade D Building Paper	Asphalt-Saturated Kraft	Two-Ply Building Paper	Vapor Barrier Paper	Reinforced Bitumen Paper
Thickness	15 mil	30 mil	60 mil	10 mil	40 mil
Moisture Resistance	Moderate	High	Very High	Very High	Excellent
Breathability	Low	High	Moderate	Low	Low
Typical Uses	Roofing, siding	Wall applications	High moisture areas	Crawl spaces	Flat roofs
Durability	Moderate	High	Very High	High	Very High

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Conclusion

Understanding the various types and applications of building paper is crucial for any construction or home improvement project. From Grade D to reinforced bitumen paper, each type serves unique purposes and offers different levels of moisture resistance and durability. Whether you’re looking to protect your home from the elements or need a reliable vapor barrier, there is a building paper that fits your needs.

As you plan your projects, consider the insights provided in this guide to select the right building paper, ensuring the longevity and safety of your home.

FAQ

What is building paper?
Building paper is a moisture-resistant barrier used in construction to protect structures from water infiltration while allowing moisture vapor to escape. It is typically made from asphalt-saturated kraft paper.

What are the different types of building paper?
The main types include Grade D building paper, asphalt-saturated kraft, two-ply building paper, vapor barrier paper, and reinforced bitumen paper, each designed for specific applications and moisture resistance levels.

Where can building paper be applied?
Building paper is commonly applied on the exterior walls of wood frame buildings, under roofing materials, in crawl spaces, and as underlay for various siding materials.

How does building paper differ from house wrap?
While both serve as moisture barriers, building paper is generally thicker and less breathable than house wrap. House wrap is often used in high-performance applications where breathability is crucial.

Is building paper waterproof?
Building paper is moisture-resistant but not entirely waterproof. It is designed to shed water while allowing water vapor to escape.

What is the thickness of Grade D building paper?
Grade D building paper typically has a thickness of about 15 mils, making it suitable for general underlayment applications.

How does the vapor barrier work?
A vapor barrier works by preventing moisture from passing through it, reducing the risk of mold growth and structural damage in areas like crawl spaces and basements.

Can building paper be used in retrofitting?
Yes, building paper can be used in retrofitting projects to improve moisture resistance and energy efficiency, particularly when adding insulation or new siding.

How is building paper installed?
Building paper is typically installed by overlapping sheets and securing them to the framing of the structure using staples or nails, ensuring a continuous moisture barrier.

What should I consider when choosing building paper?
Consider the type of application, moisture levels, and the specific requirements of your project, such as breathability and durability.