What is Roof Decking vs Roof Sheathing?
What is Roof Decking vs Roof Sheathing?
In roofing, the terms roof decking and roof sheathing are often used interchangeably, leading to some confusion. Both play critical roles in providing the necessary structural support for the roof, but there are differences in their usage, materials, and purpose.
Understanding the distinction between roof decking vs roof sheathing is essential for builders, homeowners, and contractors to ensure proper roof installation, durability, and protection against environmental elements.
Roof Decking vs Roof Sheathing
Roof decking and roof sheathing serve similar functions by providing a solid foundation for roofing materials like shingles, metal panels, or tiles. However, they differ in their materials, structure, and applications.
- Roof decking typically refers to the structural base layer of the roof, providing strength and rigidity to the roofing system. It supports the roofing material and transfers loads from the roof surface to the framing beneath.
- Roof sheathing refers to the layer of board or sheet material attached to the roof rafters or trusses. It provides a surface for attaching the roofing materials, such as shingles or metal sheets, and protects the roof from external elements.
| Aspect | Roof Decking | Roof Sheathing |
|---|---|---|
| Definition | Structural base layer supporting the roof. | Protective layer attached to roof rafters. |
| Purpose | Provides strength and transfers loads. | Protects against environmental elements. |
| Materials | Plywood, OSB, steel, or concrete. | Plywood, OSB, or wood planks. |
| Position | Below the roofing material. | Below the decking or directly under roofing material. |
Roof decking vs roof sheathing distinctions primarily revolve around their placement and function. Roof decking is often the term used for commercial roofing systems, while roof sheathing is more common in residential roofing terminology.
Is Sheathing the Same as Decking?
Many wonder, “Is sheathing the same as decking?” While the terms are frequently used interchangeably, they are not exactly the same. The difference lies in how these layers interact with the structure of the roof.
- Sheathing typically refers to the board or material that forms the outermost layer, directly beneath the roofing materials like shingles or tiles.
- Decking, on the other hand, is more often referred to as the structural layer providing rigidity to the overall roofing system.
In some cases, roof decking can refer to a specific type of roof sheathing designed for heavier loads or commercial structures. Therefore, while sheathing and decking are related, they serve slightly different functions based on the type of roof and its design.
Roof Sheeting vs Roof Sheathing
Another common comparison is roof sheeting vs roof sheathing. Roof sheeting refers to the outermost protective layer on the roof, such as metal sheets, which act as the final barrier against environmental elements. Roof sheathing, meanwhile, forms the base layer under the roof covering.
| Aspect | Roof Sheeting | Roof Sheathing |
|---|---|---|
| Definition | Outer covering of the roof (e.g., metal sheets). | Base layer supporting roofing materials. |
| Purpose | Shields the roof from weather and elements. | Provides attachment surface for roofing. |
| Materials | Metal, corrugated iron, polycarbonate. | Plywood, OSB, or wood planks. |
While roof sheeting forms the top layer of protection, roof sheathing provides a stable surface for the sheeting or shingles to be installed.
What is the Decking of a Roof?
So, what is the decking of a roof exactly? Roof decking is the foundation layer of the roof system that spans across roof joists or trusses, providing a solid platform for the installation of shingles or roofing materials. It acts as the structural backbone, ensuring that the roof can handle loads such as wind, snow, and even the weight of people walking on it during maintenance.
Common Materials for Roof Decking:
- Plywood: Used extensively in residential roofing for its durability and flexibility.
- Oriented Strand Board (OSB): A cost-effective alternative to plywood that is also lightweight and strong.
- Steel Decking: Used in commercial and industrial roofing, providing extra durability and load-bearing capacity.
- Concrete Decking: Found in larger commercial buildings, offering high fire resistance and stability.
The choice of material for roof decking will depend on the building’s use, location, and budget. For example, steel decking is preferable for industrial applications due to its strength and resistance to heavy loads.
Roof Deck and Roof Top Difference
A common confusion arises between roof deck and roof top. The roof deck refers to the structural base of the roof system, while the roof top is the exterior surface visible from the outside, typically covered with roofing materials like shingles, tiles, or metal sheets.
| Aspect | Roof Deck | Roof Top |
|---|---|---|
| Definition | Structural base supporting the roof system. | Outer surface of the roof visible from outside. |
| Materials | Plywood, OSB, steel, or concrete. | Shingles, tiles, or metal sheeting. |
| Purpose | Provides support for the roof system. | Protects building from weather elements. |
The roof deck is hidden beneath the roof top, but its importance in the overall integrity and durability of the roof structure cannot be understated.
Roof Decking vs Sheathing
The question of roof decking vs sheathing comes down to their individual roles in roof construction. Roof decking tends to be thicker and stronger since it is the foundational structure, while roof sheathing serves as a protective layer on top of the decking, securing the roof covering materials.
Key Differences:
| Aspect | Roof Decking | Roof Sheathing |
|---|---|---|
| Thickness | Thicker and stronger for structural support. | Lighter material used to hold roofing. |
| Function | Structural layer supporting roof weight. | Attaches roofing materials to the deck. |
| Installation | Installed over roof rafters or trusses. | Installed over decking or directly on rafters. |
While both are integral parts of the roofing system, roof decking plays a more structural role, whereas sheathing focuses on providing a base for roof covering attachment.
Roof Sheathing vs Decking
Another way to compare is by looking at roof sheathing vs decking from the installation perspective. Roof decking often requires heavier materials that can support the entire roofing load, while sheathing materials are lighter, designed to support the shingles or other roofing materials securely.
| Aspect | Roof Sheathing | Roof Decking |
|---|---|---|
| Installation Purpose | Holds roofing materials (shingles, tiles). | Provides overall structural support. |
| Material Type | Plywood, OSB, or other lightweight materials. | Plywood, OSB, steel, or concrete. |
| Placement | Placed above decking or directly on rafters. | Placed directly on the rafters or trusses. |
Although sheathing is often used synonymously with decking, understanding their distinct roles ensures better roofing performance and longevity.
Wall Sheathing and Roof Sheathing: Are They the Same?
Wall sheathing and roof sheathing are similar in function but differ in their placement and sometimes their material. Wall sheathing is applied to the vertical surfaces of a building, while roof sheathing is applied horizontally across the roof structure.
Differences Between Wall and Roof Sheathing:
| Aspect | Wall Sheathing | Roof Sheathing |
|---|---|---|
| Purpose | Provides structural support to walls. | Provides structural support to the roof. |
| Materials | Plywood, OSB, or other panel materials. | Similar materials, but may require waterproofing. |
| Position | Vertical installation along walls. | Horizontal installation across roof structure. |
Both are essential components in their respective applications, but they have different performance requirements due to the differences in orientation and exposure to elements.
Roof Sheathing and Roofing: Are They the Same Thing?
While some may ask, “Are sheathing and roofing the same thing?”, the answer is no. Roof sheathing refers to the structural layer beneath the roof covering that supports and holds the roofing material, whereas roofing refers to the external covering itself, such as shingles, tiles, or metal panels.
| Aspect | Roof Sheathing | Roofing |
|---|---|---|
| Definition | Structural layer beneath the roof covering. | External layer of shingles, tiles, or metal panels. |
| Purpose | Provides base for attaching roofing material. | Protects the building from weather. |
Without proper roof sheathing, roofing materials would not have the
necessary support for effective installation or long-term performance.
Conclusion
The distinction between roof decking vs roof sheathing is subtle but important for understanding how a roof is constructed. Roof decking forms the structural base, while roof sheathing is the layer that supports the roof covering. Each has its specific purpose and materials, and both play essential roles in ensuring a roof is safe, durable, and long-lasting. Understanding these terms helps homeowners, builders, and contractors make informed decisions about their roofing projects, ensuring the roof performs effectively and stands up to environmental challenges over time.