5 Simple Steps to Extend Your Deck

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Planning and Designing Your Deck Extension

If your current deck feels a bit too small and you have some extra yard space, extending your deck is a great option. Many homeowners are surprised by how easy and affordable a deck extension can be. In this guide, Deck Guardian walks you through the process in five simple steps.

Extending your deck has many benefits. It increases your outdoor space, allowing for more activities and relaxation. It also enhances your home’s value, making it more appealing to potential buyers. In this guide, prepared by the experts at Deck Guardian, we’ll walk you through the steps to extend your deck like a pro.

Step 1: Planning and Design

Before extending your deck, assess your current deck’s stability and determine the purpose of the extension. Consider factors like:


Determine the dimensions needed to enhance your outdoor space and accommodate your intended use, whether for entertaining, dining, or relaxation.


Plan how the new section will integrate with the existing deck. Consider the following factors for your deck extension layout:

  • Flow of Movement: Ensure smooth transitions between the existing deck and the new section. Think about how people will move between areas without obstacles.
  • Access Points: Plan for easy access to the new deck area from the house and yard. Consider adding steps or pathways if needed.
  • Overall Design Fit: Ensure the new section complements your backyard’s design. Align the style, materials, and colors with your existing deck and landscape for a cohesive look.


Choose materials that match or complement the existing deck. Consider durability, maintenance requirements, and aesthetics to ensure a seamless blend. The most popular choices are between wood and composite decking. Here are some things to consider for both:

  • Wood Decking: Requires regular maintenance, such as sanding, sealing, and staining to prevent weather damage. It offers a classic, natural look.
  • Composite Decking: Lower maintenance with built-in protection against the elements. Composite is often more durable and weather-resistant but can be more expensive initially.

Evaluate the existing substructure to ensure it can support the new addition. If needed, design the new section to be independently supported.

Create a detailed plan or hire a professional designer to help. Check local building codes and present your plan to the building department to obtain necessary permits. Bringing pictures of your existing deck can help explain your project and facilitate approval.

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Step 2: Preparing the Site

Before extending your deck, you need to prepare the site properly. Here’s how:

  • Clear the Area: Remove any obstacles and debris from the area where the deck extension will be built. Ensure the ground is level to provide a stable foundation.
  • Mark the Layout: Use stakes and string to outline the perimeter of the new deck section. This will help you visualize the layout and ensure accurate measurements.
  • Mark Post Locations: Measure and mark the spots for the support posts. Check local building codes for the required distances and ensure precise measurements.

Tools & Materials Needed

  • Tape measure
  • Circular and miter saw
  • Drill, driver, and assorted bits
  • Speed square
  • Rubber mallet
  • Personal safety equipment
  • Levels and clamps
  • Wrenches, sockets, and ratchets
  • Treated lumber for the new substructure
  • Joist tape for tops of joists
  • Decking boards that match or complement existing ones
  • Paint or stain to refinish existing boards to match new ones
  • Handrail system components
  • Hidden fasteners
  • Trex Universal Hidden Fastener Tool
  • Accessories like LED accent lighting, post caps, post base trims, etc.

Need help with your deck project? Reach out to Deck Guardian for expert advice and services.

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Step 3: Building the Foundation & Deck Frame

A solid foundation is crucial for your deck extension. Here’s how to build it:

  • Dig Post Holes and Pour Concrete Footings: Start by digging post holes at the marked locations. Pour concrete footings to provide strong support for the new deck.
  • Install Posts, Beams, and Joists: Following your design plan, install the posts first, ensuring they are level and secure. Next, attach the beams and joists, aligning them accurately with the existing deck.
  • Ensure the Foundation is Level and Secure: Use levels and clamps to ensure all components are properly aligned and securely fastened. This step is essential for the stability and longevity of your deck extension.

Building the Deck Frame

Constructing the frame for a deck extension can get complicated, so it’s important to be well-prepared. The placement of new joists and support beams depends on the type of extension you’re building. For multi-level decks, resources on framing multi-level decks can be particularly useful.

By carefully following these steps and ensuring precision at each stage, you’ll establish a strong foundation for your deck extension. If a DIY deck project is not for you, Deck Guardian makes extending your deck easy. Get in touch with us to learn more!

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Step 4: Adding Decking and Railings

To complete your deck extension, follow these steps for adding decking and railings:

  • Install Decking Boards: Begin by attaching decking boards to the new frame, starting from the existing deck and working outwards. Ensure the boards are aligned with the existing decking for a seamless look.
  • Secure the Boards: Use screws or nails to secure each board, maintaining proper spacing for drainage and expansion.
  • Add Railings and Features: For safety and aesthetics, install railings around the perimeter. Consider adding additional features such as stairs for access, benches for seating, or other custom elements to enhance the functionality and appearance of your deck.

Step 5: Finishing Touches

Depending on your material choice, you don’t have much to do for the finishing touches if you use composite decking. However, if you used wood, here’s a list of things to get done to complete your deck extension:

  • Sand and Seal: If you used natural wood decking, sand the new decking boards to ensure a smooth surface. Apply a sealant to match the existing deck, blending the old and new sections seamlessly.
  • Apply a Protective Finish: Protect your deck from weather damage by applying a high-quality finish. This step is important for both wood and composite decks. For wood, choose a stain or paint that matches the existing deck. Composite decks often come with a protective coating, but additional sealing can enhance longevity.
  • Add Decorative Elements: Enhance your new deck with plants, outdoor furniture, and lighting. These elements beautify the space and make it more functional for various activities.

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Extend Your Deck With Deck Guardian

By following these five simple steps, you can extend your deck and create a more enjoyable outdoor space. Start with careful planning and design to ensure a seamless integration with your existing deck. Prepare the site properly, build a strong foundation, and add decking and railings to complete the structure. Finish with protective treatments and decorative elements to enhance the deck’s appearance and durability.

Taking on this project will increase your outdoor living space and add value to your home. Remember, regular maintenance is key to keeping your deck in great condition for years to come.

For professional help and expert advice, extend your deck with Deck Guardian. Contact us today to get started on your deck extension project!

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