Your roof is made up of more than the visible roof cladding, such as asphalt shingles that all serve to protect it from the elements. The roof decking is one of these important parts that serve as the base layer of your entire roof surface.
Roof decking is a term used to describe the structural layer that provides the surface on which a roof’s weatherproofing materials are applied. The layer sits on top of the roof’s structural support and beneath the roofing materials.
Types of roof decking
The roof decking is an important element of a roof’s construction, as it provides the necessary support and stability for the roofing materials. There are several types of wood decking used for roofing, each with their own unique characteristics and features.
There are several materials that are commonly used for roof decks, including wood, concrete, and steel. Each of these materials has its own unique characteristics and benefits, and the best material for a particular roof deck will depend on the specific requirements of the project.
Wood
Wood decking is a popular choice for outdoor spaces due to its natural beauty and durability. It is also a relatively inexpensive option compared to other materials like composite or stone. Decking can be made from several materials including cedar, pressure-treated lumber, and hardwoods like ipe and mahogany.
Pressure-treated lumber is the most commonly used material for wood decks. It is treated with chemicals to protect it from rot and insect damage, making it a durable and long-lasting choice.
Cedar is another popular option, as it is naturally resistant to rot and insects. It also has a beautiful natural color and a pleasant aroma. However, it can be more expensive than pressure-treated lumber.
Hardwoods like ipe and mahogany are more expensive than pressure-treated lumber and cedar, but they are also more durable and long-lasting.
- Ipe, also known as “Ironwood,” is known for its extreme durability and resistance to rot and insects. It is also resistant to fire, making it a popular choice for areas with a high risk of wildfire.
- Mahogany is another popular hardwood for decking, as it is resistant to rot and insects and has a beautiful, rich color.
Concrete decking
Concrete roof decking is a type of flat roof construction that uses concrete as the primary structural component. It is a popular choice for commercial and industrial buildings due to its strength, durability, and fire resistance.
One of the primary benefits of concrete roof decking is its structural strength. Concrete is a very strong and durable material, and it is able to withstand heavy loads and harsh weather conditions. Due to the enormous weight of machinery, equipment, and other building materials that flat roofs are subjected to, this makes it perfect for use on them.
Concrete roof decking also has the advantage of being fire resistant because it is non-combustible, which means it won’t burn and won’t aid in spreading a fire. It is, therefore, the best option for structures that must adhere to severe fire code criteria.
Concrete roof decking is not only sturdy and fireproof, but it also requires little upkeep. It has a very long lifespan (in fact, some decks have lasted for 50 years or more) and requires little to no care or repair over that time.
Steel decking
Steel decking is a type of construction material used in the construction of buildings, particularly in the construction of roofs. It is a versatile and strong material that offers a number of benefits over other types of decking materials.
One of the primary benefits of steel decking is its strength and durability. Steel is a very strong and rigid material, and it is able to withstand heavy loads and harsh weather conditions. This makes it ideal for use on floors and roofs, which are subjected to heavy loads from equipment, machinery, and other building materials.
Another benefit of steel decking is its fire resistance since steel is a non-combustible material, which means it does not burn and will not contribute to the spread of fire. This makes it an ideal choice for buildings that need to meet strict fire code requirements.
In addition to its strength and fire resistance, steel decking is also relatively low maintenance. It does not require regular maintenance or repairs and has a long lifespan, with some decks lasting for 50 years or more.
Types of steel decking
Several types of steel decking include ribbed decks, waffle decks, and solid decks.
- Ribbed decks have a series of ribs or beams that run perpendicular to the deck surface, which provides additional strength and stiffness.
- Waffle decks have a similar structure, but the ribs run in both directions, creating a waffle-like pattern.
- Solid decks are single, solid slabs of steel with no ribs or beams.
Ultimately, the best material for a roof deck will depend on the project’s specific requirements. The roof deck’s intended usage, weight, and type of loads, local climate, and budget should be considered.
Types of wood decking
Plank decking
Plank decking is the most common type of wood decking used for roofing. It is made up of long, narrow boards that are typically 1″ to 2″ thick.
Plank decking is typically made from pine, spruce, or fir, although other species of wood may also be used. Plank decking is usually applied in a horizontal orientation, with the boards running parallel to the length of the roof.
It is commonly installed with nails or screws and a vapor barrier to prevent moisture from collecting under the decking.
Sheet decking
Sheet decking is another common type of wood decking used for roofing. It is made up of large sheets of wood that are typically 3/4″ to 1″ thick.
Sheet decking is typically made from plywood or oriented strand board (OSB). It is usually installed with nails or screws and a vapor barrier to prevent moisture from collecting under the decking.
Glued-laminated timber
Glued-laminated timber, also known as glulam, is a type of wood decking made from layers of lumber that are glued together. It is typically made from Douglas fir, but other species of wood may also be used. Glulam is stronger and more stable than timber since it is made by laminating wood layers with a moisture-resistant adhesive.
One of the main benefits of glulam is its strength and stability. It is commonly used in long-span applications, such as bridges and large commercial buildings, where traditional lumber may not be sufficient. It is also relatively low maintenance and has a long lifespan, as it is resistant to rot and decay. However, glulam can be more expensive than traditional lumber and may not be suitable for all applications.
When should you replace your wood decking?
The lifespan of wood roof decking depends on several factors, including the type of wood used, the local climate, and the quality of the installation.
In general, plank and sheet decking should be replaced when it becomes structurally unsound or when it is no longer able to provide a stable base for the roofing materials. Signs that roof decking may need to be replaced include rot, decay, or visible damage to the wood.
How much does wood decking cost?
| Type | Cost |
| Plank decking | $3 and $7 per square foot |
| Sheet decking | $5 and $11 per square foot |
| Glue-laminated timber | $6 to $34 per linear foot |
The cost of wood roof decking depends on the type of wood used and the size of the roof. Plank decking is usually cheaper than sheet decking, depending on the type of wood.
On average, plank decking costs between $3 and $7 per square foot, while sheet decking costs between $5 and $11 per square foot. These costs do not include the cost of labor or any additional materials, such as vapor barriers or fasteners.
Codes that have to do with roof decking
There are several codes and regulations that pertain to roof decking. These include the International Building Code (IBC), which sets minimum standards for the design and construction of buildings, and the International Residential Code (IRC), which sets minimum standards for the construction of single- and multi-family dwellings.
These codes specify the roof decking’s minimum thickness, wood type, fastener size, spacing, and type. Before starting a roofing project, check with your local building authorities for additional roof decking requirements.
In addition to the IBC and IRC, there are several other codes and standards for roof decking. These include the National Roofing Contractors Association (NRCA) Roofing and Waterproofing Manual, which provides guidelines for the installation and maintenance of roofing systems, and the American Wood Council’s (AWC) National Design Specification (NDS) for Wood Construction, which provides design values and load tables for structural wood products.
NRCA Roofing and Waterproofing Manual
The NRCA Roofing and Waterproofing Manual include guidelines for installing roof decking, including requirements for the spacing and size of fasteners, the minimum thickness of the decking, and the type of wood that should be used. The manual also provides recommendations for the installation of vapor barriers, which are used to prevent moisture from accumulating beneath the decking.
American Wood Council (AWC)
The AWC NDS for Wood Construction provides design values and load tables for structural wood products, including wood roof decking. The NDS specifies the minimum design values for various species of wood based on their strength and stiffness and provides load tables for calculating the capacity of wood members. Designers and engineers use these design values and load tables to ensure that the wood used in a roof’s decking system is capable of supporting the loads it will be subjected to.
Local building codes
In addition to these national codes and standards, local building codes may also have additional requirements for roof decking. It is important to check with your local building department to ensure that you are complying with all relevant codes and regulations when installing roof decking. Overall, it is important to follow all codes and guidelines related to roof decking to ensure that the roof is properly supported and able to withstand the loads it will be subjected to.
