Building a deck is a significant investment that can greatly enhance your outdoor living space. However, to ensure it’s safe, durable, and compliant with local building codes, it’s essential to ensure your contractor is adhering to specific guidelines. Here’s a comprehensive guide to help you understand what to look for so you can be confident that your contractor is building your deck to code.
1. Are They Pulling a Building Permit?
The first sign that your contractor is following local building codes is whether they’ve obtained a building permit. In most regions, a building permit is required for decks that are over a certain height, typically 30 inches above ground. This process ensures that the deck’s design complies with safety standards set by your local building department. The contractor should submit detailed plans, including the deck’s size, height, materials, and connection points. As the homeowner, ask to see the permit before construction begins. If a permit isn’t pulled for an elevated deck, it’s a red flag that the contractor might not be building to code.
2. Deck Footings: Are They Deep Enough?
The foundation of your deck is as important as the deck itself. Footings support the weight of the deck and prevent shifting over time. Local codes often specify that footings must be dug to a certain depth, typically below the frost line, to prevent frost heave—when the ground expands as it freezes and contracts as it thaws.
In warmer regions like Oregon, footings need to be 12 inches deep. In colder climates, footings may need to be 36 inches deep or more. Additionally, the diameter of the footing must be large enough to support the weight of the deck. For instance, footings might need to be 12 inches wide for a smaller deck and 24 inches or more for larger, multi-level decks.
Using concrete pier blocks that sit above the ground is not recommended, as they can shift and move, leading to instability over time. Make sure your contractor is pouring concrete to the correct depth and using post anchors to secure the deck's posts into the footing.
3. Post Anchors: How Are the Posts Being Secured?
Deck posts must be securely anchored to the concrete footings to prevent movement or uplift in high winds. The posts should be attached using metal post anchors or brackets, which also help to prevent the posts from coming into contact with soil and moisture, reducing the risk of rot. Make sure your contractor is using proper post anchors that are rated for outdoor use.
4. Ledger Board: Properly Attached with Flashing?
The ledger board is one of the most critical components of a deck attached to a house. It’s the horizontal board that secures the deck to your home that should be at least 2 x 6 inches and equal to or greater than the deck joists. If the ledger board is not installed correctly, the entire structure could become unstable.
Building codes require the ledger board to be properly anchored to the house’s framing. It should never be attached to brick veneer, stucco, or siding without proper blocking and support. The board must be fastened using lag screws or through bolts, not nails or regular screws, to ensure it stays securely in place. Bolts or lag screws with a minimum diameter of ½ inch are generally required, and codes typically specify two staggered rows of fasteners to distribute the load. Your contractor should space the fasteners according to the load requirements, which may be every 12 to 24 inches.
Additionally, the ledger board must be protected with flashing—a waterproof barrier that prevents water from seeping into the home’s structure. Flashing is usually made from aluminum, galvanized steel, or vinyl and is installed under the house's siding and over the ledger board. Without flashing, moisture can get into the house, cause rot, and lead to structural damage both to the deck and the house. Be sure to ask your contractor how they plan to install the ledger board and flashing, and inspect it before the decking boards are laid.
5. Metal Joist Hangers: Are They Using the Right Hardware?
One of the most overlooked but critical components of a deck’s structural integrity is the hardware used to connect the various parts. Metal joist hangers are essential in ensuring that joists (the horizontal boards that support the decking) are securely attached to the ledger board or beams.
Joist hangers must be made of corrosion-resistant materials, typically galvanized or stainless steel, to prevent rust, especially in outdoor environments exposed to moisture. The building code requires that the fasteners (nails or screws) used with joist hangers are also corrosion-resistant. Standard screws or nails should never be used with joist hangers, as they can corrode and weaken over time. You can ask your contractor about the type of hangers and fasteners they’re using, and verify that they meet local code requirements by referencing the product packaging or the manufacturer’s specifications.
6. Railing and Stair Codes: Are They Meeting Safety Standards?
One of the most important safety aspects of any elevated deck is its railing system. Building codes require railings on decks that are more than 30 inches above ground. The height of the railing should be at least 36 inches in most jurisdictions.
Balusters, the vertical posts in the railing, must be spaced no more than 4 inches apart to prevent children from slipping through. When it comes to stairs, tread depth must be at least 9 inches, and risers (the vertical part of the step) should not exceed 8 inches in height. A continuous handrail is required for stairs with four or more risers.
Check with your contractor to ensure these dimensions are being followed, and request to measure the railing and stairs yourself during construction.
7. Are Beams and Joists Sized Properly?
The structural framework of your deck—namely, the beams and joists—must be sized and spaced according to the deck’s size and load-bearing requirements. Building codes specify how much weight a deck must be able to support, typically measured in pounds per square foot (psf). For residential decks, the code usually requires a load-bearing capacity of at least 40 psf for live loads (furniture, people, etc.) and 10 psf for dead loads (the weight of the deck itself).
Joists are usually spaced 12, 16, or 24 inches apart, depending on the decking material and the span they need to cover. However, if you are using composite decking, deck joists must be 16 inches apart or less to maintain the manufacturer's warranty.
The size of your deck joists depends on the span of the deck. For example, if spaced 16 inches apart, joists that spans 12 feet should be at least 2 x 10 inches in size, while shorter spans may only require 2 x 8 joists. Beams should also be appropriately sized for the spans they cover, often 4 x 8 or larger, depending on the deck’s size.
8. Lateral Load Connections: Added Stability
In many areas, building codes require additional lateral load connections for decks attached to a house. These connections help prevent the deck from pulling away from the home, especially under heavy loads or strong winds. Lateral load connectors are metal brackets that tie the deck framing directly to the home’s structure, providing added stability. If your contractor is attaching the deck to your house, ask if they are using lateral load connections and whether they meet local requirements.
9. Check for Proper Deck Board Gaps
The spacing between your deck boards may seem like a small detail, but it plays a critical role in your deck’s longevity. Deck boards typically need gaps of 1/8 to 1/4 inch to allow water to drain and air to circulate. This prevents debris and moisture from getting trapped, which can lead to wood rot. Ask your contractor how they plan to space the deck boards, and check the gaps once the boards are in place.
10. Ask for Inspections at Key Stages
In most areas, local building departments require inspections at different stages of the deck’s construction. These inspections are designed to ensure the deck is being built to code. For example, an inspector may check the footing depth and placement before concrete is poured, and they may also check the framing and attachment to the house before decking is installed. Make sure your contractor is scheduling these inspections and ask to see the results for each inspection stage.
Final Thoughts
A deck that’s built to code is not just a safe and durable structure—it also protects your investment and adds value to your home. By asking the right questions, being involved in the inspection process, and checking for key elements like joist hangers, post anchors, and proper railing height, you can feel confident that your deck will stand the test of time. Don’t hesitate to consult with your local building department or hire an independent inspector if you have concerns during the construction process. With the right contractor and the proper adherence to building codes, you can enjoy your new deck with peace of mind for years to come.
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