Building Codes for Decks – Requirements & Specifications

Building a deck is a great way to transform your outdoor space into a more appealing and functional area for relaxation and entertainment. To ensure the deck’s safety and durability, adhering to specific building codes is essential. 

These building codes for decks exist to prevent accidents and ensure the lifespan of the construction. Code regulations address structural integrity and the use of proper materials, and understanding these codes is crucial for a successful deck process.

Stay with us, as we’ll explore deck-building codes while providing you with all the knowledge you need to start your deck project confidently.

Key Takeaways:

• Following local deck-building codes ensures safety, structural integrity, and legal compliance for any deck project.

• Specific codes regulate every part of a deck—including railings, stairs, joists, and footings—with requirements often based on the IRC and local modifications.

• Obtaining a building permit is typically required and protects homeowners from legal issues and insurance complications.

Deck Code Requirements

Deck code requirements can vary in each area

Building codes provide durable and safe installations. They protect the homeowners and maintain their insurance coverage. Building codes address structural guidelines, stair and railing requirements, materials, and other parts of construction processes. 

Every area has different code requirements, so it’s highly important to check with your local building authorities for guidelines and necessary permits for a specific state or city before you start searching for different deck ideas.

There are some general deck-building codes, and they require the following:

1. A wood deck needs to use 5/4 or 2″ x 6″ for the given span.
2. A composite deck has to be installed per the given manufacturer’s specifications with cited span requirements.
3. For decks that are higher than 30″ off the ground, you need railings.
4. The height of the stair handrail has to be between 34″ and 38″ measured vertically from the nose of the stair tread.
5. It’s required that the load strength is a minimum of 50 pounds per square foot.
6. It’s required that the stairway width is a minimum of 36″.
7. Tread depths on stair steps may not exceed ⅜”, as well as variations between riser heights.
8. Depending on the local building codes and requirements, footing posts can be 4′ x 4′, 4′ x 6″, 6′ x 6′, or 8′ x 8′ sized lumber.

Here’s the table showing those general building codes.

Deck-Building Requirement	Code Specification
Wood deck boards	Must use 5/4 or 2″ x 6″ boards for the given span.
Composite deck boards	Must follow the manufacturer’s span and installation specifications.
Deck height and railings	Railings are required if the deck is more than 30″ above the ground.
Stair handrail height	Must be 34″–38″ measured vertically from the stair tread nose.
Load strength	Must support a minimum of 50 pounds per square foot.
Stairway width	Must be at least 36″ wide.
Tread and riser consistency	Tread depth and riser height variations must not exceed ⅜″.
Footing post sizes	Can be 4″x4″, 4″x6″, 6″x6″, or 8″x8″ depending on local building codes.

Table 1: General building codes

Codes can vary depending on whether it’s attached to the house or not, and also on the deck design. Respecting these requirements provides legal compliance and enhances the safety of the deck. 

Besides following these codes, obtaining the necessary permits is a crucial step in the deck construction process. In case you are wondering, do you need a building permit for a deck, the answer is – in most cases, yes. 

When constructing a deck, having a building permit is an important part of the process, as building without a permit can cause legal issues. The building permit cost ranges between $140 and $3,000 and ensures that all local regulations and safety standards during the deck construction project are met.

Now, let’s discuss different deck parts in more detail.

Building Codes and Specifications for Different Deck Parts

A deck is constructed with different parts, each with a specific function that ensures its durability, safety, and stability.  Every part has its building codes that must comply with local regulations. Let’s discuss each deck part and some of its codes in more detail.

Deck Railing Height Code

Deck railings are there to prevent injuries and falls. There are various railing designs, so you can choose which style fits your aesthetic the most. 

To pass the inspection and be in compliance with regulations, you need to know that the railing of a deck has to be 36 inches high for all decks that are higher than 30 inches above the ground and that the spacing and attachment for installing deck guard posts can vary by location, but they should be installed at the corner of the rim joist for the railing. 

Deck Stairs Code

Decks can’t have stair risers higher than 7 3/4 inches, and the depth of treads has to be at least 10 inches. Stairs with 4 or more risers require handrails that must be positioned between 34 and 38 inches above the tread nosings, as the IRC says. 

Deck Footers Code

To prevent shifting during the process of freezing and thawing, footers must extend below the frost line. In colder regions, they need to be deeper than in warmer climates, where they are usually 12 inches deep. The precise depth is defined by the IRC, but it can be changed and adjusted depending on the local climate conditions. 

Baluster Spacing Code

To prevent children and people from slipping through, baluster spacing in deck railings can’t be more than 4 inches. This is a very important requirement that is outlined in the IRC. 

Deck Framing Code

The framing of a deck includes the joists, ledger board, and the beams that support the deck. Details on load capacities and materials are specified more in the IRC.

Deck Support Posts Code

To support the deck’s load, support posts have to be put precisely, of adequate size, and spaced in a way that they can support the deck. 

Deck Joist Code

Deck joists need to be spaced 12” or 16” in the center for most materials, but other materials, such as wood decking and some composites, can go up to 24” in the center. Blocking rows should be installed every 4′ to 6′ for better stability. To attach the joists to the beam securely, use joist hangers that match the required capacities.

Here’s a table showing codes and specifications for different deck parts.

Deck Part	Code Requirement
Deck Railing	Min. height: 36″ (if deck > 30″ above ground); post at rim joist corners
Deck Stairs	Max riser: 7¾″; min tread depth: 10″; handrail height: 34–38″ (if ≥4 risers)
Deck Footers	Depth: ≥12″ (varies by climate; must go below frost line)
Baluster Spacing	Max gap: 4″
Deck Framing	Follow IRC specs for loads and materials
Support Posts	Size and spacing must support full deck load (e.g., 4×4, 6×6, etc.)
Deck Joists	Spacing: 12″, 16″, or 24″ on center; blocking every 4′–6′; use rated hangers

Table 2: Specifications and codes for different deck parts.

Now, let’s discuss building codes for residential decks in more detail.

Building Code for Residential Decks

A residential deck is an outdoor structure mostly made from different composite materials or wood and attached to a building or a house. If planning to construct a residential deck, respecting building codes to maintain structural integrity, safety, and compliance with local laws is important.

Some of the requirements for residential decks include:

• Footings – Footings for a deck have to be extended below the frost line, typically 12 inches deep, to prevent movement during the process of freezing and thawing.

• Guardrails – For decks that are higher than 30 inches, guardrails that are 36 inches tall are required, and the balusters in guardrails need to be more than 4 inches apart to keep the children safe.

• Stairs – Stair risers can’t be higher than 8 inches, and the treads have to be at least 10 inches deep according to the IRC. Stairs that have four or more steps need to have handrails, and they have to be positioned from 34 to 38 inches above the stair nosings. 

• Ledger Board – The ledger board of a deck that is attached to the house needs to be securely fastened with bolts or lag screws, not nails, and flashed in a proper way to avoid any potential water damage.

• Joist Spans – The span of the joists depends on the spacing and type of wood; for example, a 2×10 joist that is spaced 16 inches apart can span up to 14 feet according to the IRC.

• Load Requirements – Decks need to be able to support a live load which is 40 pounds per square foot and a dead load of 10 pounds per square foot. 

The table below summarizes building codes for residential decks.

Deck Component	Code Requirement
Footings	Depth: ≥12″ (must extend below frost line)
Guardrails	Required if deck height > 30″; min. height: 36″; max. baluster gap: 4″
Stairs	Max riser: 8″; min tread depth: 10″; handrail height: 34–38″ (if ≥4 steps)
Ledger Board	Must use bolts or lag screws (no nails); proper flashing required
Joist Spans	Example: 2×10 joist @ 16″ OC spans up to 14′
Load Requirements	Live load: 40 psf; dead load: 10 psf

Table 3: Residential deck building codes

For more specific requirements, always consult the local building department. In the text below, we’ll discuss different deck types and their codes.

Deck Types and Their Codes

Decks can be designed in many different ways so they can fit specific needs and environments. Understanding the requirements of each type is essential for a successful project. Let’s see some of the most common deck types and their codes.

Free-Standing Deck Code

As its name suggests, this type of deck stands independently, as it’s a structure that’s not attached to any building. The codes for this type of deck must have proper bracing and anchoring to make sure the structure is stable. 

Deck Attached to House Code

Deck codes for this type of deck include ledger board attachment, flashing, and proper joist hangers to prevent any possible water damage. 

Floating Deck Building Codes

Ground-level decks or floating decks are built close to the ground and not attached to any structure. Codes for these decks include proper drainage, ventilation, and moisture barriers. 

Wooden Deck Building Code

Codes for this type of deck usually refer to the type of wood that can be used and standards for structural components like railings, beams, and joists. 

After exploring different deck types, the most important thing to consider is the codes that regulate not only deck construction but also construction in general. 

Let’s find out everything about IRC and IBC codes, as they play a crucial role in making sure that all decks meet structural standards and safety regulations.

IRC and IBC Deck Code

The International Residential Code (IRC) and the International Building Code (IBC) are a set of rules and regulations that set up the minimum standards for the construction of buildings, including decks. 

They are established by the International Code Council (ICC) and they represent the basis for codes all over the USA and many other countries.

Deck Building Codes: IRC vs IBC Explained

The IRC:

• Used for townhouses and two-family apartments that have no more than three floors.  
• Has detailed rules and requirements for deck construction, like joist and beam spans, the size and depth of footings, handrail dimensions, etc. These codes serve as a guideline for inspectors, builders, and architects to make sure they comply with rules and safety regulations (IRC deck building codes pdf).

On the other hand, the IBC: 

• Focuses on all types of buildings, such as commercial and multifamily residential structures, as well as all types of construction that don’t belong to the scope of the IRC. 
• Has stricter rules than the IRC, especially for multi-family homes and commercial properties (structural strength, accessibility, and fire resistance). 
• Requires more durable materials and designs, especially for decks that are a part of commercial establishments and are made for a larger number of people.

The differences show that the IRC is designed for smaller-scale residential projects, while the IBC is used for more different of building types. 

These codes are crucial for deck building as they ensure compliance with local rules and regulations, as well as the safety and structural integrity of a deck. By following them, we prevent deck failures. 

Now, in the following text, let’s see the codes when it comes to different states.

Building Codes for Decks in Different States

Building codes for decks can vary from state to state because of differences in climate, soil conditions, and local regulations. Many states follow the previously mentioned IRC as a baseline, but there’s also a need for modifications to address certain local needs.

States with colder climates need deeper footings to extend below the frost line, while states that are closer to the coast have stricter rules when it comes to flood resistance and wood. Many states have specific rules when it comes to stair dimensions, railing heights, and materials.

Let’s see some of the specific code requirements for different states.

Building Code for Residential Decks in Virginia

The building code for residential decks in Virginia has to comply with the IRC, along with some local modifications. Some of the specific requirements are that deck footings have to extend below the frost line, which is around 24 inches, and guardrails have to be over 30 inches high and attached to the house properly. 

Ohio Building Codes for Decks

The state of Ohio has its own Ohio Residential Code that respects the rules of the IRC. Specific regulations include that footings have to be below the frost line, 32 inches deep, and guardrails need to be over 30 inches in height with baluster spacing that is no more than 4 inches. 

Deck Railing Code Michigan

In the state of Michigan, decks that are higher than 30 inches need to have guardrails that are at least 36 inches tall. The balusters must be spaced no more than 4 inches apart, with footings that are extended below the frost line, which in some areas, can be up to 43 inches deep.  

Florida Deck Building Codes

Deck building codes for Florida are focused on hurricane and wind resistance so that decks are safe to withstand strong winds. In Florida, decks that are higher than 30 inches must have guardrails that are at least 36 inches tall, with unique requirements for materials and fasteners for preventing corrosion in coastal areas.

Before starting any construction, be sure to check the rules and regulations with your local building department so you can have a safe and smooth construction process.

Following the Deck Building Codes Ensures Safety

By following deck-building codes, we ensure the safety of the homeowners and visitors. These codes reduce the risks of any potential collapses, accidents, and costly repairs and provide structural integrity. 

And to meet all legal requirements before the construction process begins, don’t forget to obtain a site plan for permits. It’s a crucial step for a successful project. 

If you need help with obtaining a site plan, feel free to contact us. Our experienced team will be more than happy to answer all your questions. We provide detailed and accurate plans that meet all requirements and ensure a successful process.