Here is How to Secure a Deck to Your House

Freestanding decks are the right choice for many homeowners. But that doesn't mean it's the right choice for you. If your next home improvement project is attaching a deck to your home, make sure you do it the right way, the first time, so you don't have to worry about expensive repairs later.

Factors to Consider

Keep the following factors in mind when getting your new deck attached to your home.

Deck Materials

The types of materials that compose your deck can make a difference in just how you attach it to your house foundation. Composite decking is generally heavier than pressure-treated wood decking, for example, meaning you may need to have sturdier framing.

Building Codes & Permits

Ensure that the new deck you will build and attach to your home is in full compliance with your municipality's building codes and that you have all required permits to begin.

Type of Deck

The type of deck you install will influence how you attach it to your home as well as dictate the types of permits you need.

• Ground-level decks are typically easier to install than elevated decks.
• Elevated decks often require more building permits and railings while also needing sturdier deck framing and deck joists than ground-level alternatives.
• Cantilevered decks also often require more permits and need greater structural support than a standard ground deck.

Step-by-Step Guide to Secure Decks to House

Evaluate Sturdiness

Before doing anything else, evaluate your house frame to ensure it can support the weight of an attached deck. This evaluation can include hiring professionals to assess your home or it can involve you personally inspecting rim joists and wall framing for signs of damage, including water damage and rot.

Get Permits

Once you've determined that your home can support a deck, get the proper building permits before starting any new deck construction or adding on to any existing deck.

You can learn more about residential deck guidelines in the City of St. Louis here and St. Louis County here.

Lay Out & Install Footings

Deck footings are necessary for most types of decks. You'll often want them in grid patterns with each footing about 4 to 8 feet apart; the exact number will vary based on factors like local building codes.

Once you've determined the right layout, dig holes below the frost line (usually at least a foot deep) where you want your footings to live. Then, pour concrete into the hole and let it cure completely.

Add Support Posts

Once the concrete has cured, add your support posts.

Begin by adding post brackets and/or bases to the top of the footing. From there, attach posts to the brackets and secure them with exterior-grade fasteners.

Prep the Home

Your home may need modifications before you can start attaching a deck. For example, if your home has siding, you will need to remove it before you can begin. You will also need to clean the area of your home where you will attach the deck thoroughly (and let it dry) before moving on to the next step.

Mount the Ledger Board

The deck ledger board supports your entire deck. It needs to be extraordinarily sturdy, so use moisture-resistant materials like Trex® composite boards or pressure-treated wood.

The ledger board should be the same height as all of your joist framing and temporarily attached to the house (typically the home's rim joist or sill plate) with framing nails; this step helps keep the board steady as you secure it with your structural fasteners, which can be lag screws, lag bolts, or carriage bolts and washers.

Location is everything when placing structural fasteners. They ideally should be at least 2 inches away from the top and bottom of your ledger and nearly 4 inches away from each end. Rows should be horizontally staggered to create a W pattern, with each row being nearly 2 inches to 5 inches apart. Each fastener in a row should be spaced out using this formula: 100 inches / joist length (feet).

Install the Flashing

Deck flashing protects both your home and deck from water damage. After installing the ledger board, add ledger flashing like an L-shaped drip edge or Z-shaped vinyl flashing. Secure flashing using roofing nails, with nails spaced roughly a foot apart. You can add deck sheathing over the flashing for enhanced moisture protection.

Reinstall Siding

Reinstall your siding using corrosion-resistant staples, screws, or nails.

Secure Deck Beams

Deck beams (girders) are foundational parts of your deck's load-bearing framing. You will typically need double beams for a sturdy deck. Use nails on both sides of the two beams to connect them. Then, secure the double deck beams to your ledger board and support posts with nails.

Add Joists

After beams are securely in place, it's time to add joists.

Start with rim joists (band joists), using heavy-duty screws or joist hangers to connect the joists with the ledger board and beams. Next, install floor joists. Each should be roughly 1 foot to 1.5 feet apart, attached to beams using specialty joist hangers.

Start Blocking

Blocking provides extra stability to joists. Blocks should be roughly 6 to 8 feet apart in a grid-like pattern, secured to floor joists with exterior-grade, heavy-duty nails and/or screws.

Install Railing

You can install railing before or after laying deck boards.

Begin with marking where you want each rail post, keeping each post an even distance from each other. Then, start securing the railing posts to the joists, with the bottom of the post reaching the bottom of the joist. You can use a clamp to hold each rail in place while using carriage bolts or structural screws to secure the railing posts.

Next, install the railing top board (handrail) and bottom board (base rail) on the railing posts with exterior-grade mounting screws. Then, mark where you want each baluster to go, add connectors to the ends of each baluster, put the baluster where you've marked the top and bottom boards, and secure the connectors to the boards using exterior-grade nails or screws.

Lay the Decking

It's time to start laying decking boards. Place your deck boards on top of (and perpendicular to) your floor joists with appropriate fasteners, such as structural screws. Each deck board should be roughly an eighth of an inch to a quarter inch apart, allowing ample room for water drainage and board expansion.

Get an Inspection

Your job doesn't stop after the deck is laid. Most locations require a licensed professional to inspect the completed deck to ensure it is compliant with all local laws and regulations.

Remember: If you're unsure how to secure a deck to a house safely, you can always hire professionals to do the job for you. They can ensure your deck is safe, secure, and completely compliant.

Disclaimers: This article is for general informational purposes only. Please check the local building codes in your area to ensure complete compliance with all laws and regulations.