How Long Does a Deck Substructure Last?

When you have a deck substructure, you have a lot of things on your mind when it comes to maintenance. You want to ensure that it is always in good shape so that your deck can withstand the elements. Many people wonder about the longevity of their deck’s substructure.

A pressure-treated deck substructure can last up to 40 years, while a cedar frame may only last 15-20 years. The lifespan of a deck substructure is primarily determined by the materials used for the wood frame. However, the key to longevity for any deck substructure is proper maintenance. 

In this article, we will lay out the best materials for building a deck substructure, the best maintenance practices, and what you need to consider when planning your deck build. We hope this article will help you extend the life of your deck substructure so that you can enjoy your outdoor space for many years to come.

Understanding the Deck Substructure

Before we jump into the lifespan and all the particulars that come along with extending your deck substructure’s longevity, let’s ensure we’re on the same page about what a substructure is.

how long does a deck substructure last

A deck substructure comprises the foundation and framing of your deck. This includes everything from the ledger board (which attaches your deck to your house) to the joists and beams that support your decking boards. In short, the substructure is everything that supports your decking boards.

The lifespan of your deck substructure will depend on several factors, including the materials used and how the substructure was built. But with proper maintenance, you can extend the life of your deck substructure and enjoy your outdoor space for many years to come.

Materials Used in Deck Substructure

When it comes to choosing materials for your deck substructure, there are a few things you’ll want to keep in mind. 

First, you’ll want to choose materials that are durable and will stand up to the elements. You’ll also want to consider the weight of the materials you choose. The heavier the material, the more likely it is to sag over time. And finally, you’ll want to choose materials that are easy to work with and install.

Let’s take a look at some of the most popular materials out there and how they can benefit your deck substructure. 

Material 1: Pressure-Treated Lumber

One of the most commonly used materials for deck substructures is pressure-treated lumber

The wood is usually treated by forcing chemicals into it, protecting it from moisture-related issues like decay and fungus. It’s also more affordable than other options, making it a great choice for budget-conscious homeowners.

Pressure-treated lumber is available in various sizes and grades, so you’ll be able to find the perfect lumber for your project. Ideally, you’ll want to choose lumber that is treated to be able to survive continuous exposure to the ground, labeled as “ground contact.”

Ground contact lumber has twice the concentration of chemicals as standard pressure-treated lumber, which ensures its longevity even when exposed to the elements. It’s also heavier than standard pressure-treated lumber, so it’s less likely to sag over time.

Pressure-treated lumber is the ideal choice for homeowners who are looking for an affordable, durable, and easy-to-use material for their deck substructure.

Pressure-treated lumber can last anywhere from 15-40 years with proper maintenance.

Material 2: Cedar

Cedar is another popular choice for deck substructures because of its durability. Cedar grows in damp climates, so the wood has natural oils that protects it from insect infestations and issues of dampness and decomposition. 

This natural resistance means that cedar doesn’t have to be specially treated before it can be used in projects where the wood is exposed to the elements. Cedar is also a lightweight wood, so it’s less likely to sag over time.

Cedar is more expensive than pressure-treated lumber, but it’s also more beautiful. The rich color and grain of cedar add natural beauty to any deck. Being a softwood, it is also easy to use, making cedar an ideal choice of material for your deck substructure. 

The wood lasts a long time without rotting, with well-maintained decks lasting more than two decades. 

Material 3: Redwood

Redwood is frequently used for deck substructures despite being more expensive than pressure-treated lumber. The high tannins in the wood makes it naturally resistant to a number of issues –  from insect attacks to damp and rot. The tannis also discourages fungal infections. 

A redwood substructure can last up to 20 years with proper maintenance.

Material 4: Composite

Composite materials are also a popular choice for deck substructures. They are made from a mixture of wood fibers and plastic, making them resistant to rot, insect damage, and weathering.

Composite materials are more expensive than pressure-treated lumber but are also low maintenance. You won’t have to worry about sanding, staining, or painting your composite substructure. These materials are a great choice if you’re looking for a durable, low-maintenance material for your deck substructure.

Composite generally lasts around 25-30 years.

Building Your Deck Substructure

Now that you’ve chosen the perfect materials for your project, it’s time to start building your deck substructure.

Building a deck substructure is a relatively simple process, but there are a few things you’ll need to keep in mind.

  • Measure the area where your substructure will be built. This will ensure that your substructure is the correct size and shape, without any surprises when it comes to installation. 
  • Excavate the area where your substructure will be built. This will give you a level surface to work on. You’ll need to mark the perimeter of your substructure. This will help you keep track of where your substructure is located.
  • Install the joists. The joists are the horizontal pieces of lumber that support the decking.
  • Then, install the decking. The decking is the finished surface of your deck.
  • Finally, install the railing. The railing is the handrail that goes around the perimeter of your deck.

When building your substructure, be sure to choose the best material for your environmental conditions. For example, if you live in an area with a lot of moisture, choose a material that is resistant to rot and decay.

Building a deck substructure is a simple process that can be completed in a few hours. With the help of a friend or family member, you’ll be able to enjoy your new deck in no time.

How To Properly Maintain Your Deck Substructure

Now that you have your shiny new deck substructure, it’s important to maintain it properly. By following these simple tips, you can be sure that your substructure will last for many years to come.

  • Keep an eye on your substructure. Ensure that you check your substructure every year for issues like rot and fungal growth, insect infestations, and other weathering. 
  • Keep it clean. You can protect your deck substructure from rot and decay by keeping it clean. Cleaning the wood prevents any build up of grime and dirt that might encourage dampness and damage. 
  • Repair any damage immediately. Don’t wait to repair damaged wood. The longer you wait, the worse the damage will become.
  • Apply a sealant or stain regularly. This will help protect your substructure from weathering and UV damage.

If you’re interested in woodworking or DIY, a pallet fence is another project you may be interested in. Find out more about the lifespan of a pallet fence and what you can do to extend it in my complete guide. [How Long Will a Pallet Fence Last?]

How To Choose the Best Sealant or Stain for Your Materials

When it comes to choosing a sealant or stain for your deck substructure, there are a few things you’ll need to keep in mind.

  • You’ll need to decide what type of finish you want. You can choose from various finishes, including clear, tinted, and solid colors.
  • Choose a sealant or stain that is compatible with your material. For example, if you have a composite substructure, you’ll need to use a composite-specific sealant or stain.
  • Ensure that the sealant or stain you choose is designed for outdoor use. This will ensure that your substructure is protected from the elements.

When choosing a sealant or stain, be sure to select the best product for your needs. This will help you get the most out of your deck substructure.

Warning Signs That It’s Time To Replace or Repair Your Deck Substructure

While a deck substructure may last for many years, there are some warning signs that it may be time to replace or repair it.

Here are four signs to watch out for:

  • Cracks in the concrete or wood.
  • Sagging or unevenness in the deck surface.
  • Rot or decay in the wood.
  • Rust on the metal fasteners or brackets.

If you notice any of these signs, it’s important to have a professional inspect your deck substructure and make repairs or replacements as necessary. Ignoring these warning signs could lead to a collapsed deck, which could injure you or others.

The Bottom Line

Overall, when it comes to the lifespan of a deck substructure, there are a few factors that will play a role. These include the material used, the environment, and the level of maintenance.

Your deck substructure can last for many years with proper care and maintenance. Be sure to inspect your substructure regularly and make repairs or replacements as needed. By following these simple tips, you can be sure that your deck substructure will last for years to come.

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