It’s easy to forget just how complex a roof truly is. On your average day, you just see the external material, and that’s it. There’s so much more to it than the outer layer, and a crucial element is the roof decking. Roof decking is your base. It’s what everything is built on, and it deserves your care and attention.

Understanding the ins and outs of roof decking is a welcome piece of knowledge for any homeowner. It’ll help you understand the materials used to build your home and the nuances involved with repairs. Many of you might be dealing with a classic plywood system, and others will have newer, more innovative materials in place.

Whatever your roof decking is made from, we have useful information for you in this article. Read on, and we’ll share precisely what roof decking is, the types of material it is constructed from, and what the installation process looks like.

  • Is all roof decking made from plywood?
  • Is roof decking installation a DIY job?
  • How can you maintain your roof decking?

What Is Roof Decking?

Your roof decking is the layer that all of the outer materials of your roof sit on. Imagine your roof completely bare so that you can see the timber trusses or rafters. The roof decking is the material that sits on top of the timber. It forms a layer to which you can attach further materials such as underlayment, tiles, and shingles. You won’t see much of it, but without it, you don’t have much of a roof.

Roof Decking Materials

Almost all roof decks are made from one of two materials: plywood or OSB. That isn’t to say there aren’t other options, but the majority of roofs will use one of these. There are pros and cons to each, so it’s important to weigh up your options.


This is the most traditional of roof decking materials. If you’re dealing with a home that hasn’t had a roof repair or replacement in many years, it will almost certainly have a plywood deck. The criss-cross layered wood veneers create a strong material that can carry the materials above and bear the brunt of the weather. That’s especially important in colder climates where snow can build up on roofs, adding to the weight. Plywood is, however, a more expensive choice compared to OSB.

OSB (Oriented Strand Board)

OSB has rapidly grown in popularity over recent years, edging plywood out in many building projects. It’s formed by compressing and bonding strands of wood together. It creates a sheet that has a more uniform structure throughout. Plus, it delivers that at a price that’s more affordable than plywood. You’ll often see OSB used in projects where the budget is tighter.


It’s rare that you’ll find a metal roof decking in a residential home, but it is used on commercial and industrial premises. Metal is often a choice when the roof needs to support large, heavy machinery (such as aircon units or generators) or it needs to support foot traffic. The beauty of metal decking is that it is incredibly durable and requires little in the way of maintenance. The downside, however, is that it’s far more expensive to purchase and install.

How To Install Roof Decking

This process is unlikely to be a stand-alone project, as you’ll almost certainly immediately move on to the full roof replacement. It is, however, good to get into the details of how roof decking itself is installed.

Step 1: Preparation

The first thing you need to do is prepare your work area. Remove any old material and debris. You should also ensure that you’re wearing the correct protection necessary for roof work. It’s also imperative that you take this opportunity to investigate the trusses or rafters and ensure that they’re in good order. They need to be able to support the decking above.

Step 2: Laying the Decking

Always start at the edge of the roof and work your way across to the other. Take a sheet of your material and attach it to your timber. Depending on the roofing material you’re using, you may have to leave expansion gaps (plywood) or pay credence to the overlap markers (OSB). Each sheet should either be screwed or nailed in place. Check with local building codes for advice on which.

Step 3: Waterproofing

The raw sheet material won’t add much protection from water. You’ll need to add a layer of this. Some properties will have a specific waterproof system in place before underlayment. Others will have a waterproof underlayment. Whichever you have, now is the time to install and attach it to the sheets.

Step 4: Inspection

Ensure that you carefully inspect each sheet that you’ve installed and that it is securely in place. Remember that you won’t have easy access to it for, potentially, a long time. Check for any risen or loose nails, and if there are any rough edges, these are sanded down.

Roof Deck Maintenance

The main method of maintaining your roof decking is to regularly inspect it. Check to see if you can see any signs of wear and tear. These signs include:

  • Moisture and visible water
  • Cracks
  • Warping
  • Bowing

The sooner you spot these issues, the easier they will be to remedy. Another great way to proactively maintain your roof is to remove any debris that falls onto the roof, such as leaves, twigs, and other materials.

Is roof decking for you?

The first step will be to select your materials. Once you’ve done that, the installation of roof decking is relatively straightforward. The trick is to ensure that you install it accurately and precisely so that further materials can be installed without issue.

  • Make sure that your choice of material is appropriate for your climate.
  • Whenever installing roofing material, make sure you’re leaving ventilation.
  • If in doubt, reach out to a professional for advice.

Roof decking not for you? You need to speak with a professional roofing contractor. Here at Trenton Roofing, roof installation is our specialty. Give us a call. We’d welcome a conversation about your project.

Alex Valentino

Alex Valentino – Vice President

Leading the way for the company’s second generation of family and employee ownership, Alex’s mission is to create lasting relationships built on trust and respect by providing uncompromising workmanship and unparalleled customer service. With a focus on safety and consumer education, Trenton Roofing strives to set the bar for the advancement of the roofing industry and the betterment of our local communities. When he is not working, Alex can be found traveling with his fiancée, watching football or playing a relaxing round of golf with his friends.