Roof Decking vs. Sheathing: What’s the Difference?

When planning a roofing project, you’re bound to encounter technical terms that might seem the same but are actually different. Roof decking and sheathing are perfect examples of this. Although both are crucial components of a roof’s structure and the terms are used interchangeably, they refer to specific parts that are distinct from each other. 

In this post, we clarify the difference between decking and sheathing and discuss their relevance to your roofing system.

Roof Decking

Roof decking serves as the foundation layer upon which all other roofing materials are installed, including underlayment and shingles. It’s essentially the base that connects the roof structure, including trusses and joints, creating a solid surface. Typically, it is made from sheets of plywood or OSB (oriented strand board), with thickness and type selected based on local building codes and the specific requirements of the roofing material.

Roof Sheathing

While sheathing is often used interchangeably with decking, it specifically refers to the panels that form the first layer attached to the roof’s rafters. Sheathing plays a pivotal role in distributing weight evenly across the roof and providing a flat surface for roofing materials. To minimize the need for a roof repair, both sheathing and decking must be installed properly.

Plywood vs. OSB

Roof decking and sheathing materials should not only be strong but resistant to moisture and temperature changes. Plywood, known for its superior resistance to moisture, is often preferred in areas with high humidity or frequent rainfall. OSB, while more cost-effective, expands and contracts more with changes in moisture levels, which can affect your roof’s long-term durability. 

Considerations for Installation

Attention to detail during the installation of sheathing can prevent issues such as warping or swelling due to moisture. For both decking and sheathing, the material must be installed with no gaps. They must be properly secured to the roof’s structure to ensure the longevity of the roof. Hiring a reputable roofing contractor ensures the proper installation of these components and the entire roofing system.

A1 Roofing & Construction understands the nuances between roof decking and sheathing. You can count on us to ensure that each step of the installation process is executed with precision. Call us at (401) 265-1019 or fill out our contact form to schedule a consultation. We serve clients in Providence and Warwick, RI, as well as New Bedford, MA.