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Posted by: Hook Agency

Roof Sheathing Thickness: Options, Tips, & More

Calender 09/26/2023
Clock 5 min READ

Are you ready to start your next roofing project?

But need some help determining the ideal roof sheathing thickness for your home or commercial building? We’ve faced and gained a solid understanding of the same challenge.

This article will guide you to choose the best thickness based on factors like your chosen material – plywood or oriented strand board (OSB). The minimum allowable roof decking thickness is as slim as 3/8 inches! So let’s plunge into this pool of knowledge.

Understanding Roof Sheathing Thickness

beautiful single family home

Roof sheathing thickness is an essential consideration for both residential and commercial buildings. It determines the strength and stability of the roof, as well as its ability to withstand wind, snow, and other weather conditions.

Standard roof sheathing thickness for residential and commercial buildings

Residential and commercial buildings typically follow legal guidelines regarding roof sheathing thickness. For these structures, experts recommend a thickness of ⅝ inch, while conventional roofing often ranges from ½ inch to 5/8 inches thick.

Choosing less than the suggested ⅝-inch thickness could lead to bowing between framing, negatively affecting the structural integrity of your building. In the case of metal roofs, we see a typical range between 22 and 29 gauge in terms of standard thickness.

And more importantly, codes dictate that sheathing should be at least 19/32-inch thick as a minimum requirement for optimal safety and durability standards.

Minimum thickness requirements

Upon choosing materials for roof sheathing, the minimum thickness considered is vital to ensure stability. The least allowed sheathing thickness should be ⅜ inch, whether you opt for plywood or OSB types.

This standard applies when setting up roof structures like trusses or rafters, offering adequate strength and support.

Further specifications illustrate that 19/32 inch forms the barest thickness that sheathing must maintain. Common choices in residential roofing involve either 1/2 or 5/8-inch thick roof sheathings, while a preference for OSB often settles on its 7/16 variant.

These selections of roof sheathing thickness guarantee both resilience and high performance under various weather conditions.

Factors influencing sheathing thickness

Several factors can influence roof sheathing thickness, such as the material used. Plywood, oriented strand board (OSB), wood boards, concrete, and exterior gypsum board have different thickness requirements based on their specific properties.


Close up to plywood roof

Plywood is a popular choice for roof sheathing due to its strength and flexibility. It comes in various thicknesses, typically 3/8″ to 3/4″. The chosen thickness depends on load requirements, span distances, and roofing materials.

Plywood’s durability is well under heavy snow or wind loads, making it ideal for roofs in harsh climates. Its resistance to shrinking, twisting, and warping adds to the longevity of your roof.

Proper installation of plywood is crucial, as improper fitting can compromise the performance and safety of the roof structure. Therefore choosing the right-sized plywood ensures optimal lifespan for your roof.

Oriented Strand Board (OSB)

Oriented Strand Board (OSB) is a popular choice for roof sheathing due to its durability and cost-effectiveness. OSB has become a common building material for walls, floors, and roofs made from thin wood strands bonded with water-resistant resin.

It is used in residential structural design for safe and efficient home construction. Unlike plywood, which can delaminate over time, delaminations are virtually nonexistent in OSB.

It’s important to note that OSB has higher thickness swelling under extreme conditions than plywood. Overall, OSB provides a solid option for roof sheathing that balances strength and affordability.

Wood boards

Wood boards are popular for roof sheathing due to their durability and affordability. They come in various thicknesses, the most common being 1×4 or 2×6 boards. These boards are typically installed perpendicular to the rafters or trusses, providing a solid base for the roofing materials.

It is important to note that wood boards may require additional support if they need to be thick enough, as they can sag under heavy loads. Therefore, it is crucial to choose the appropriate thickness based on factors such as roof slope and climate conditions.

Wood boards offer a cost-effective option for roof sheathing while still providing structural integrity and support.


close up to concrete mix

Concrete is a significant factor to consider when determining the thickness of roof sheathing. The International Building Code (IBC) mandates that corrosion-resistant metal with a minimum thickness of 0.019″ should be used for roofing sheathing, which also applies to concrete.

In the City of Healdsburg, complete information about proposed sheathing products must be submitted for review, including those involving concrete. When researching roof sheathing thickness options, it’s important to note that relevant searches often include millimeters measurements and choices available for Oriented Strand Board (OSB) sheathing.

Building codes also regulate wall sheathing thickness for load-bearing capacity and structural support purposes.

Exterior Gypsum Board

Exterior Gypsum Board is a specialized drywall panel commonly used in single-family homes. It has a moisture-resistant, noncombustible core covered by glass-mat facers on both the front and back.

This type of sheathing can be an alternative to plywood for roof applications. Additionally, it offers the benefit of being fire-resistant when using a type X gypsum board. The thickness of exterior gypsum sheathing will depend on factors such as the material, application, and environment of the roof.

When considering roof sheathing options, exploring all available choices is essential to ensure you select the best one for your specific needs and requirements.


Knowing the right roof sheathing thickness ensures structural integrity and durability. The recommended thickness of ⅝” provides sufficient strength and prevents bowing between framing.

It’s important to note that the minimum thickness requirement is 3/8 inch. Factors such as plywood, oriented strand board (OSB), wood boards, concrete, and exterior gypsum board can influence the sheathing thickness.

By understanding these options and tips, you can make informed decisions when choosing the right roof sheathing for your residential or commercial building.

Keep the quality and performance of your roofing project high. Contact us today and explore our exceptional range of roof sheathing materials. Build with confidence and make your roof the crowning glory of your home.

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