Deck Beam Size Calculator

Beam Type: Span (ft): Load (psf):

Building a strong deck means picking the right beam size carefully. A beam holds up the deck’s weight and sends it to the posts and footings. The size of the beam depends on how much weight it carries and the gap it crosses.

Most beams are built using the same lumber as the joists. They’re made by nailing 2 or 3 boards together. It’s good to keep the beam depth like the joists for looks. But for heavier loads, you might need special engineered beams.

Steel I-beams are the toughest beams, able to handle over 20 feet spans. But they cost more, are heavier, and harder to use than wood beams.

Key Takeaways

Deck beam size depends on how much weight it supports and the gap it covers.
Typical beams are made by nailing 2 or 3 boards, matching the joists in size and type.
For long spans needing more than usual, you might need engineered beams.
Steel I-beams are the top choice for strength but come with more cost and weight.
Matching the beam depth to the joists helps the deck look even.

Understanding Deck Beam Loads and Spans

When you build a deck, knowing about beam loads and spans is key. The span of a beam changes based on wood type, size, and the load it bears. A double ply beam of treated southern pine, grade no. 2, spans a foot for every inch deep it is. This works when it supports joists across a 12-foot space with no extra material past the beam.

Calculating Beam Loads

Deck joists support deck areas, and beams support these areas. It’s advised to keep support beams within 12 feet if your deck is under 6 feet high. Usually, a single beam near the edge of the deck is enough. The other end is supported by a ledger attached to the house.

Determining Beam Span Requirements

In some places, residential decks only need to bear 40 PSF. Always check local rules. A guide provides details on beam size and support placement, considering joist length, wood type, and post spacing. Beams installed with a cantilever are stronger. This comes from the wood’s strength rather than bolts. For a cantilevered beam, ensure a 6″ clearance above the ground. Install beams with the curved side up to keep the deck level and avoid sagging. The curve on a piece of lumber’s narrow side is the crown. Joists’ crowns must face up after installation for a strong structure.

Beam Species	Beam Size	Max Span @ 50 PSF	Max Span @ 60 PSF
Southern Pine	3’4″ – 14’11”	3’0″ – 13’9″	3’0″ – 11’10”
Douglas Fir-Larch	3’2″ – 13’8″	2’10” – 12’4″	2’4″ – 11’10”
Redwood	3’11” – 12’4″	2’0″ – 11’10”	1’9″ – 11’10”

The table above gives max beam spans for different species and sizes, under varying snow loads. For effective span, joists and their cantilevers have factors from 0.66 to 1.00, depending on the ratio.

Selecting the Appropriate Beam Size

Choosing the right beam size for a deck is key to its strength and safety. Beams can be as small as 1-2×6 or as large as 3-2×12. This choice depends on the deck’s size, how much weight it will hold, and how you want it to look. For the corners, footing can be from 6 to 17 inches, and for the middle, it ranges from 9 to 24 inches.

Considerations for Single vs. Multiple Beam Configurations

Small decks might need only one beam, but bigger ones could need more to spread out the weight. By looking at a joist span table, you can figure out the right joist sizes for different lengths. Choices include 2x8s, 2x10s, or 2x12s. Posts can be spaced 12″, 16″, or 24″ apart. Deciding on one beam or many depends on what the project needs and the space available.

Deck Beam Size and Material Types

There’s various materials for creating deck beams, like pressure-treated wood, regular lumber, and engineered beams. You can pick from Southern pine, Douglas fir, and other woods for your beams. Hardwoods like redwood and cedar are great but cost more. For very long beams, you might need engineered options which are more expensive, like LVL or APB.

“Sawn lumber has limitations compared to engineered wood products, with bending strength often half that of engineered options and clear-span distances restricted for long spans.”

When picking beam material, think about cost, what’s available, and how you want it to look. The project’s load requirements also heavily influence the choice of beam size and material.

Beam Span Charts and Tables

Deck beam span tables and charts are super helpful for homeowners and contractors. They help choose the perfect beam size for deck projects. These tools show the biggest safe spans for different sizes and types of lumber. They consider live load, dead load, and how much the beam can bend.

The Deck Beam Span Table makes picking the right support easier. For example, a Redwood 4×6 beam shouldn’t go over 6 feet without support. Compare that to a 4×8 Hemlock beam that can reach 9 feet without a post. A 3×10 Hemlock beam does even better, spanning up to 11 feet.

Even within the same kind of wood, span distance changes with beam size. For Douglas Fir and Pine, a 4×6 beam goes 6 feet, but a 3×8 beam can reach 9 feet. And a 4×8 beam can go as far as 10 feet without support.

The table also covers beams like a 3×10 going up to 11 feet, and a 4×10 up to 12 feet. But a 3×12 beam’s span isn’t listed. This table emphasizes that Hemlock beams span the furthest. Generally, larger beams mean longer span distances for all listed woods.

These beam span guides prove very useful. They help homeowners and contractors choose the right deck support. By knowing how beam size affects distance, wise decisions can be made.

The right beam span depends on lumber type, beam size, and what it supports. There are many kinds of wood beams like Southern Pine and Cedar. Special mixes can also be used. For big orders, shipping costs can be high. Sometimes, these costs are five times more than the wood price itself.

If wood beams aren’t right, steel beams could be better. They are strong, straight, safe, and don’t catch fire easily. With steel, you need fewer supports. So, your view from inside can be better. Plus, getting steel might lower your home insurance cost.

Wood Species	Beam Size	Maximum Span
Redwood	4×6	6 feet
Hemlock	4×8	9 feet
Hemlock	3×10	11 feet
Douglas Fir / Pine	4×6	6 feet
Douglas Fir / Pine	3×8	9 feet
Douglas Fir / Pine	4×8	10 feet
Douglas Fir / Pine	3×10	11 feet
Douglas Fir / Pine	4×10	12 feet

The Dimensional Lumber Deck Beam Spans table gives a full look at the biggest safe spans. It’s a must-have for anyone working on a deck project.

Engineered Beams vs. Dimensional Lumber

Choosing between engineered beams and dimensional lumber beams greatly affects a deck’s strength and future performance. Engineered beams, like I-joists or laminated veneer lumber (LVL), bring several benefits over old-school lumber beams.

Advantages and Disadvantages of Engineered Beams

Engineered beams can cover larger areas, supporting deck beams up to 20 feet long. This factor makes them perfect for projects needing longer beams. They are also usually stronger and more consistent than basic lumber beams. Yet, they do cost more than regular decking materials.

Types like glulam and parallam go through special making processes that make them tougher. Glulam beams, for example, are created by stacking lumber layers that are then glued together. Parallam beams, on the other hand, are made by gluing wooden strands in a microwave process. These options are often the go-to for long beam projects because they offer the needed strength.

Yet, if your deck doesn’t need beams to span too far, traditional lumber beams might be more budget-friendly. They can still be a good choice, especially if it fits within their typical span limits. Just be sure to look into the beam size and material carefully for the deck’s stability.

Engineered Beams	Dimensional Lumber Beams
Longer span capabilities (up to 20 feet)	Shorter span capabilities
Stronger and more stable	Moderate strength and stability
More expensive	More cost-effective
Glulam and parallam options available	Traditional lumber materials

If you’re planning a deck project, taking a close look at engineered beams versus lumber is key. This helps you pick the right choice for your situation, taking both needs and budget into account.

Knowing the good and not-so-good about each beam type lets you make a smart choice. You’ll ensure your deck is strong and lasts while not ignoring the price factor.

Beam Installation and Support

Getting the beams rightly placed and fastened is very important for the deck’s strength. Beams need to be firmly attached to the posts with connectors. These posts should stand straight and be anchored properly to the ground for a firm base. The beams must sit in a way that gives enough support to the joists. The exact placement depends on the deck’s design and what the local rules say.

Proper Beam Placement and Fastening

How beams connect to the posts really matters for the deck’s strength. You should use special connectors, like metal hangers or brackets, to attach beams to posts. Bolting them together correctly is key. This makes sure the deck can safely hold the weight it needs to.

Utilize the “3, 4, 5 method” to square a corner for determining a 90-degree angle off the house where the edge of the deck will be built.
Make notches on a 6×6 post to support a double beam, specifically for a 2×10 double beam.
Use ½”x7″ hot-dipped galvanized bolts, nuts, and washers for beam-to-post attachment.

Beam-to-Post Connections

The way beams connect to posts is key for the deck’s stability. Use strong connectors to fasten beams to posts. Securing them with lag screws or bolts is vital. It helps the beam and post support the deck’s weight safely.

Make sure post-to-beam connectors are placed tightly against the wood when you install them. Fill up all the holes from the fasteners. This keeps the connection strong. Also, putting a mending plate above the post-cap flange adds extra support. It makes the beam connection even stronger.

“Proper beam installation and support are crucial for the long-term structural integrity of a deck. Careful attention to detail during the beam placement and connection process will ensure your deck remains safe and stable for years to come.”

Local Building Codes and Regulations

Building a deck means you must follow local building codes and regulations. Things like live load, dead load, and fastener needs can vary a lot by where you are. You need permits and must design your deck to meet all these rules for it to be safe and legal.

Deck height is very important. If your deck is over 30 inches high without railing, you need a rail that’s at least 36 inches high. In Canada, decks over 24 inches high need a guard, and the guard height changes with the deck’s height.

Stair width has a minimum of 36 inches. Stairs over 30 inches high must have treads that are at least 10 inches deep. The risers can’t be more than 7.75 inches high.

Deck load requirements are key as well. You usually need a live load of 50 pounds per square foot strength. Cantilevers for joists and beams can’t be more than one-quarter their span.

Talking to the building department in your area is a must. They can help with permits and other rules like setbacks and easements. This ensures your deck is built to the right standards.

Knowing the local building codes and regulations helps a lot. It means your deck will be safe and fit to use. Make sure to get the right permits for a hassle-free outdoor area.

Conclusion

Choosing the right deck beam size is key for a safe and strong deck. Understand what affects the beam’s load and span needs. Use span charts and follow local codes to pick the best beam size. The common beam length for pallet racking is 96 inches. This size can hold two 40-inch pallets. For pallets up to 42 inches wide, a 96-inch beam is also recommended. Beams should be at least a loaded pallet’s height plus the beam thickness plus 4 inches of lift-off space. A 6-inch lift-off space works even better. It’s advised to have a 6-inch space above the load for taller pallets and better loading visibility.

Connecting the beams correctly to the posts is crucial for a deck that lasts. About 6,500 people have been hurt in the U.S. because of deck or balcony falls since 2003. The North American Deck and Rail Association says the U.S. has about 40 million decks that are over 20 years old. DCA 6 has rules for building decks, like how far apart the joists can be, the size of the posts, and the spacing of the nails or screws. Following these rules is vital for your deck’s safety and life.

When selecting your deck beam size and planning your deck framing, deck structure, and deck construction, it’s good to follow the best advice. With the right details and careful work, your DIY deck can be beautiful and strong. A well-made deck will be enjoyed for many years, giving you peace of mind.

FAQ

What is a deck beam?

A deck beam is a strong part of a deck’s structure. It’s held up by posts and footings. It supports the joists and the weight they carry.

How is the size of a deck beam determined?

Deck beams are sized based on how much weight they hold and how far they stretch. One beam might be enough for small decks. But big decks need several beams.

Wooden beams from pressure-treated lumber are budget-friendly. They work well for decks even when using different wood for the surface and railings.

What are the common materials used for deck beams?

Deck beams are often made from pressure-treated Southern pine and other woods like Douglas fir. Options include Redwood and Cedar, known for their durability but with a higher cost. For really long spans, engineered beams are sometimes the best choice, although they’re more expensive.

How are deck beam spans calculated?

The length a beam can span is figured by looking at the type of wood, its size, and what it needs to carry. Span charts help find the right span for different kinds of lumber. They consider the weight the beam must bear.

What are the advantages of using engineered beams?

Engineered beams like I-joists or LVL can cover longer distances than regular ones. They are costly but can hold more weight and span further.

How should deck beams be installed and supported?

It’s important to attach beams securely to the posts. This is done using special connectors. The posts should stand straight and be held well by their footings.

Beams should be placed so they fully support the joists and follow the deck’s design. Make sure the spacing meets local building codes.

What are the local building code requirements for deck beams?

Always check your area’s building codes for deck rules. These can cover the weight the deck must bear, the size of the beams and joists, how far apart the posts can be, and what fasteners to use.

Deck Beam Size Calculator