What is Roof Sheathing? (And Why it Matters)

What is Roof Sheathing

Your roof is much more than its shingles. A roofing system consists of numerous and necessary components. Much like a home, a roof requires a foundation to depend on. Roof sheathing serves this exact purpose. 

Adam Vaillancourt Roofing is here to help break down the ins and outs of roof sheathing and why it matters. At the end of the day, your roof plays a key part in protecting your home and those within from various weather elements and extreme conditions. Sheathing is a big part of that. 

What is Roof Sheathing?

Also known as roof decking, roof sheathing is a sturdy layer of wood boards attached to the roof’s trusses and joints for additional levels of support. The roof’s shingles are attached to the sheathing tiles or planks of wood. 

Plywood, EPDM rubber boards, and other specialty materials are commonly used to make sheathing what it is today. 

Types of Roof Sheathing Materials

As mentioned, sheathing is curated through several different types of materials. Each of these materials comes with pros and cons. Factors such as durability cost, sustainability, type of building, and local climate all play a role with each type of roof sheathing material. 

Let’s look at each type of roof sheathing material and showcase their pros and cons. 

  • Plywood

Plywood is a roof sheathing material made up of thin composite layers of wood held together by glue. Each layer is meticulously angled with each other to prevent warping. The most common variation of plywood used for sheathing is CDX plywood. 

CDX plywood is known for its superior levels of durability and the ability to withstand extreme weather, even though it can be up to 19% lighter than EPDM rubber boards. Additionally, when CDX plywood swells with moisture, it dries out at a quick rate, preventing fast degradation. 

 On the other hand, plywood is one of the more expensive options. 

  • EPDM Rubber Boards

Oriented strand boards are wood paneling made with wood strands and waterproof heat-cured adhesives. 

EPDM rubber boards use the parts of trees that typically aren’t able to be used in other wood materials and are often between eight and 15 centimeters long. 

EPDM rubber boards are notably less expensive than the plywood variety. And because this material is heavier, thermal conductivity is also enhanced. 

Unlike CDX plywood, oriented strand boards act like a sponge. So when moisture is present, they take longer to dry out and end up degrading faster. Additionally, because this material is heavier, the installation process tends to be more labor-intensive. While CDX plywood looks like real wood, EPDM rubber boards look more like strips of wood, which could be an area of focus for select homeowners. 

  • Other specialty materials

Other materials like concrete, ​​exterior gypsum boards, or plasterboard panels have been used for roof sheathing in certain situations. Concrete is commonly used when the highest level of support and durability is needed. Exterior gypsum boards or plasterboard panels were much more popular in the past but are still marketed as the cheaper alternative to CDX plywood and EPDM rubber boards. 

How Roof Sheathing Protects Your Home 

To protect your home and maintain the roof’s integrity, roof sheathing provides a stable base for roof materials. While shingles play a role in the protection of your home, the combination of the two systems provides proper reinforcement.

The reinforcement and durability of sheathing also hold steady against excessive weight of snow, wind, and other weather conditions. Along similar lines, the addition of sheathing to a roof also improves insulation and energy efficiency.

How to Know When Your Roof Sheathing Needs Replacement

Since roof sheathing isn’t always accessible or visible, how do you know when it needs to be replaced? Here are some indicators it’s time for replacement: 

  • Sections of the roof sagging
  • Leaks
  • Water damage in nearby areas
  • Soft or spongy spots on the roof
  • Visible spots of rotting 
  • Mold 

Damaged roof sheathing is much like other areas of damage in your home, putting it off has the potential to spiral out of control. Even the smallest leak, a section of sagging, and a spot of water damage can swelter and cause bigger issues for your home. 

Whether those issues call for costly repairs or the roof’s integrity is compromised, these are far more difficult to deal with, piling on stress and costing you more. Certain problems like mold growth can also hinder the health of your home’s occupants, making it a health concern as well. 

Roof Sheathing and Building Codes

It’s important to note roof sheathing has to follow certain building codes and regulations. The 2018 International Residential Code states roof coverings (materials) shall be applied in accordance with applicable provisions of this section and the manufacturer’s installation instructions.

This residential code is important because your local roofing contractor must abide by all the installation instructions from the material’s manufacturer. Examples include the requirement that more than a 1/8” gap between the planks must be replaced before nails and fasteners can be applied to the material, per the manufacturer’s installation instructions. Not following these codes could void the warranty on the materials purchased. 

It’s not uncommon for poor roofing contractors to incorrectly follow nailing patterns and spacing. Not only can this void the warranty, but the roof’s structural integrity could be at risk. This creates opportunities for sheathing issues and damages to become more likely. This makes the need for a professional and experienced roofing contractor all the more important when it comes to all facets of roof sheathing. 

The Cost of Roof Sheathing

The cost of roof sheathing is dependent on multiple factors. Material costs, labor costs, complexity of installation, pitch of the roof, and building height are the main set of factors affecting the price of roof sheathing. 

The biggest set of factors known for increasing the cost of sheathing are materials and the complexity of installation. The choice of CDX plywood will cost more in terms of the material choice but will be easier to install, decreasing labor costs. Oriented strand boards are cheaper upfront but because of their heavy nature, the installation process is more complicated, leading to a rise in labor costs. Depending on the building’s height and design, costs may vary higher or lower. 

Get Your Roof Inspected by Our Expert Roofers

Roof sheathing, but more importantly, high-quality sheathing is a necessary layer of support for your roof. Sheathing creates a sturdy foundation to withstand large amounts of weight, withstand adverse weather conditions, add insulation, and boost energy efficiency within your home. 

When you’re looking to get your home’s roof sheathing inspected in Massachusetts and southern New Hampshire, choose Adam Vaillancourt Roofing. Contact us today for expert roof inspections and professional advice.

Adam Vaillancourt Roofing proudly offers other residential roofing services such as roof repair, roof cleaning, roof rejuvenation, roof replacement, inspections, metal roofing, and gutter services.