What Is Roof Decking?

Tom Gaffey
by Tom Gaffey

The structure of a building can be quite complex. Your eye normally only sees the walls, exterior and roof shingles. There is, however, a plethora of more intricate structures and networks hiding behind the facade.

If you consider your home as a structure, the roof is certainly one of the most important elements involved. When you look at the roof you only see the shingles, which fight against the natural elements in order to keep the home dry and insulated. Shingles are only the first line of defense. It is the roof decking that is perhaps the most critical part of your roof and its success.

Roof decking is the material that connects to the structural components of your roof. It also serves as the flat surface for your roof’s shingles to be placed. Roof decking should be able to withstand a certain amount of weight in order to prevent a roof collapse. There are many materials used for roof decking. The most popular are wood, concrete, and steel.

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Roof Decking Defined

Roof decking is the part of your roof that connects your roof to your house. In other words, roof decking is the foundation of your roof. This means that quality roof decking is very crucial.

More specifically, roof decking is the boards or tiles that fill the space between the rafters, trusses, and beams. Roof decking also provides a flat surface where the remaining elements of the roof can be placed.

If you do not have solid roof decking then the foundation of your roof may be weak. This can lead to several issues, the most serious of which is the collapse of your roof.

Is Roof Decking The Same As Sheathing?

You may hear the roof foundation referred to as roof sheathing, or simply as “sheathing.” Do not be confused, as these terms mean the same thing. Both roof decking and roof sheathing refer to the underlying structure that connects the roof to the structural elements of the house.

Where You Will Find Roof Decking

Roof decking is an important part of a building’s structure, but you likely will not see it. The only time you will see roof decking is likely when you see a home being built. That is because roof decking is located just above the rafters of your home.

Above the roof decking is where the underlay and shingles for your roof are placed. The shingles are the only part of the roof you see, but the roof decking is a critical part of the strength and stability of your roof.

Different Types Of Roof Decking

Roof decking can be made of all sorts of materials. There is no law when it comes to what material you must use. However, some zoning and housing codes may require a certain type of material to ensure durability and safety. Although you can use many types of materials for roof decking, there are a few materials used most commonly.


Concrete is one common material used when it comes to roof decking. It is a very strong and durable material. Concrete roof decking will often be used if there are plans to use the roof for a functional purpose (i.e. a roof deck that can hold weight). Using concrete roof decking is also a good option when a building may continue to be built upon. If you plan to build another story to your home you will likely use concrete roof decking.


Sheets of steel are another popular type of roof decking. Steel, like concrete, is fairly durable. Although it cannot hold the weight of a concrete can, it is still strong. Steel is also lighter than concrete. In fact some types of steel roof decking are incredibly light weight while still obtaining the ability to withstand strong impacts. This makes it one of the better options when it comes to roof decking material.


Wood is the most popular material for roof decking. It is fairly light weight, and also often the most economical of the roof decking options. There are several rules, however, when it comes to using wood as a roof decking material. Be sure the type of wood is up to code if you plan to use it for this purpose. There are specific types of wood that are less flammable and more water-resistant than others.

Why Roof Decking Is Necessary

Not only is roof decking necessary, but it is arguably the most important component of the entire roof. The necessity for roof decking is twofold. First, roof decking provides a flat and stable surface that helps adhere the roof. This layer also provides the vessel between the core structure of the house and the rooftop. Roof decking even provides an added and secure layer of defense against outdoor elements.

When You Should Replace Roof Decking

As you likely know, roofs need to be replaced from time to time. Depending on the type of roof shingles you have, you will likely replace yours anywhere between every 10 to 25 years. This all depends on the type of materials you use for the shingles.

Roof decking does not always need to be replaced at the same time as your roof shingles. The best route to take is to investigate the quality of your roof decking once the old shingles have been removed.

Sometimes, due to water damage or poor installation, roof decking will need to be replaced at the same time as the roof. Keep in mind that the quality of the materials you used for the initial roof decking also play a role in its longevity.

Signs That Your Roof Decking Needs To Be Replaced

It is always a good idea to check your roof decking when you replace your roof. It is often the only time you have a chance to see its integrity with your own eyes. There are, however, several other signs that indicate your roof decking needs to be replaced.

  • Visible Mold, Mildew, or Other Signs of Moisture Leakage in Your Attic
  • Roof Shingles Falling Off 
  • Visible Exposed Patches On Roof
  • Water Stains On Your Walls
  • Noticeable Insect Infestations
  • Holes Or Water Leaks In Roof

If you witness any situation like those listed above it is wise to contact a roofing specialist immediately. The roof decking likely needs attention and may need to be completely replaced. Even if the issue is not the roof decking, mold and water damage likely will only worsen over time. It should be addressed sooner than later.

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Putting A Lid On It

Roof decking, although often unseen by the homeowner, is an intricate part of a building and its integrity. Simply defined, roof decking is that flat surface that connects your home to the roof.

Choosing the right type of roof decking is dependent on your plans for the roof itself. Wood, steel, and concrete tend to be the most popular types of roof decking, but they are not the only materials used when roof decking a building.

Although roof decking does not always need to be replaced at the same time as your shingles, it should not be neglected. Strong and solid roof decking helps ensure a stable and lasting roof, so be sure it does not deteriorate.

Tom Gaffey
Tom Gaffey

Tom Gaffey is an expert writer who currently resides in Washington D.C. Tom has a passion for real estate and home improvement writing, as well as travel and lifestyle writing. He lived the last twelve years in Hawaii where he worked closely with luxury resorts and event planners, mastering his knowledge of aesthetics and luxury products. This is where he found his passion for home improvement and a keen interest in DIY projects. Currently, Tom resides in Washington D.C, and also working on his debut fiction novel.

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