roof sheathing thickness

Posted On: June 15, 2024

How to Determine the Best Roof Sheathing Thickness for Your Roof

Roof sheathing is a critical component of any building structure, providing support, stability, and a foundation for roofing materials. When it comes to selecting the appropriate thickness for your roof sheathing, there are several factors to consider, including:

  • Climate
  • Building codes
  • The type of roofing material you plan to use

In this blog post, we’ll delve into the various considerations involved in determining the best roof sheathing thickness for your specific needs.

Understanding Roof Sheathing

Before diving into thickness considerations, it’s essential to understand the role of roof sheathing. Roof sheathing, also known as roof decking, is the layer of material that sits on top of the structural roof framing and beneath the roofing material itself. It serves as a base for attaching shingles, tiles, or other roofing materials, while also providing structural support to distribute the load of the roof evenly across the framing members.

Common materials used for roof sheathing include plywood and oriented strand board (OSB). These materials are chosen for their strength, durability, and suitability for various weather conditions. Both plywood and OSB come in different thicknesses, typically ranging from 3/8 inch to 3/4 inch, although thicker options are available for specific applications.

Factors to Consider

  • Climate: The climate in which your building is located plays a significant role in determining the appropriate thickness of roof sheathing. In regions prone to high winds, heavy snow loads, or frequent storms, thicker sheathing may be necessary to provide additional structural support and resist damage from extreme weather conditions.
  • Building Codes: Building codes and regulations set forth minimum requirements for roof sheathing thickness based on factors such as roof slope, building height, and local climate conditions. It’s essential to consult local building codes to ensure compliance and determine the minimum thickness required for your project.
  • Roofing Material: The type of roofing material you plan to use can influence the thickness of the roof sheathing required. Heavier roofing materials, such as clay tiles or slate, may require thicker sheathing to support the added weight adequately. Additionally, some roofing materials may have specific installation requirements that dictate the minimum thickness of the sheathing.

Calculating Load Requirements: 4 Steps

To determine the appropriate thickness of roof sheathing for your project, you’ll need to calculate the anticipated load that the roof will need to support. This includes the weight of the roofing materials, as well as any additional loads such as snow, wind, or equipment placed on the roof.

1) Dead Load:

The dead load refers to the weight of the roofing materials themselves, including shingles, tiles, or metal panels. This weight varies depending on the type and thickness of the roofing material chosen. Consult the manufacturer’s specifications for the dead load of your chosen roofing material.

2) Live Load:

The live load accounts for additional weight that the roof may need to support, such as snow accumulation, equipment, or maintenance workers. Local building codes typically specify the minimum live load requirements based on factors such as roof slope and climate conditions.

3) Wind Load:

In areas prone to high winds, the roof sheathing must be able to withstand significant wind loads without failure. Thicker sheathing may be required to provide the necessary strength and stability to resist wind uplift forces.

4) Snow Load:

For regions with heavy snowfall, the roof sheathing must be capable of supporting the weight of accumulated snow without buckling or collapsing. Thicker sheathing may be necessary to distribute the snow load evenly and prevent overloading of the roof structure.

Consulting Structural Engineers

In complex or high-risk projects, it’s advisable to consult with a structural engineer to assess the specific load requirements and determine the appropriate thickness of roof sheathing. A structural engineer can perform detailed calculations and analysis to ensure that the roof sheathing meets or exceeds the necessary strength and stability requirements for the project.

Choosing the Right Material

Once you’ve determined the appropriate thickness of roof sheathing based on load requirements and other factors, it’s time to select the right material for the job. Plywood and oriented strand board (OSB) are the most common options for roof sheathing, each with its own advantages and considerations.


Plywood is made from thin layers of wood veneer that are glued together in alternating grain patterns to improve strength and stability. Plywood is known for its dimensional stability, resistance to moisture, and ease of installation. It is available in various grades and thicknesses to suit different applications.

Oriented Strand Board (OSB):

OSB is made from compressed strands of wood fiber that are bonded together with adhesive and wax. OSB is known for its strength, affordability, and consistent quality. It is typically less expensive than plywood and is available in larger panel sizes, making it ideal for covering large roof areas quickly.

Considerations for Installation

Proper installation of roof sheathing is essential to ensure optimal performance and longevity of the roofing system. Follow these guidelines to achieve a successful installation:

  • Ensure proper ventilation: Adequate attic ventilation is essential to prevent moisture buildup and prolong the life of the roof sheathing. Install ridge vents, soffit vents, and/or gable vents to promote airflow and reduce the risk of condensation.
  • Use the correct fasteners: Choose corrosion-resistant nails or screws that are appropriate for the thickness and type of roof sheathing being installed. Follow manufacturer recommendations for spacing and placement of fasteners to achieve the required holding strength.
  • Follow manufacturer guidelines: Always refer to the manufacturer’s installation instructions and guidelines when installing roof sheathing. Proper installation techniques are crucial to achieving the desired performance and durability of the roofing system.

Get The Recommended Roof Sheathing Thickness

Selecting the appropriate thickness of roof sheathing is a critical decision that can impact the structural integrity and longevity of your roofing system.

Consult with building professionals, such as structural engineers and roofing contractors, to ensure that your roof sheathing meets or exceeds the necessary strength and stability requirements. With careful planning and proper installation, you can enjoy a durable and reliable roofing system that provides years of protection and peace of mind.Contact Northface Construction to get started!


Work With Minnesota's Top Roofing Contractors

Let's Get Started