How Far Can A Double 2×8 Deck Beam Span

How Far Can A Double 2×8 Deck Beam Span

When it comes to building a deck, understanding the span capabilities of your deck beams is essential. In this article, I will explore the span requirements for a double 2×8 deck beam and provide you with important information to ensure the structural integrity of your deck.

The span of a double 2×8 deck beam is determined by factors such as the length of the deck joists and the specific building codes in your area. According to the 2015 International Residential Code (IRC), a double 2×8 deck beam can span up to 8 feet 9 inches when the deck joists are 6 feet long. However, if the deck joists are 8 feet long, the beam span is reduced to 7 feet 7 inches.

It is important to note that these span values are based on the IRC guidelines. If your joist length is not listed in the table, it is recommended to consult with your local code official or use the shorter value in the table as a conservative estimate. For example, assuming the allowable span as 7 feet 7 inches would be a safe approach in such cases.

When constructing a double 2×8 deck beam, it is crucial to ensure proper fastening and joint placement. The built-up beams should be fastened together using a minimum of 10d nails spaced 16 inches on-center along both edges. Additionally, the joints in the beam layers must align over posts for maximum stability. It is important to follow these guidelines to maintain the structural integrity of your deck.

Furthermore, it’s worth mentioning that beams can also cantilever a certain distance between posts. The IRC allows beams to cantilever up to one-quarter of the beam span between posts, which provides additional flexibility in designing your deck.

Key Takeaways:

  • The span of a double 2×8 deck beam depends on the length of the deck joists and local building codes.
  • According to the 2015 IRC, a double 2×8 deck beam can span up to 8 feet 9 inches with 6-foot-long joists and 7 feet 7 inches with 8-foot-long joists.
  • When the joist length is not listed in the table, it is recommended to consult with your local code official or use the shorter value in the table for a conservative estimate.
  • Proper fastening and joint placement, with 10d nails spaced 16 inches on-center, are crucial for the stability of built-up beams.
  • Beams are allowed to cantilever up to one-quarter of the beam span between posts.

Deck Joist Span and Spacing

When it comes to building a deck, one of the key considerations is the span and spacing of the deck joists. The size and spacing of the joists will determine the structural integrity and load-bearing capacity of your deck. Let’s take a closer look at some important factors to consider.

Joist Spacing

The spacing of deck joists is typically 16 inches on center, but this can vary depending on local building codes and the installation instructions for the decking material. It’s important to consult the specific requirements for your jurisdiction to ensure compliance. Additionally, some decking materials, particularly those installed at a 45-degree angle, may require a reduced joist spacing of 12 inches on center for added support.

Joist Size and Span

The size of the joists will determine the allowable span between joists. Common joist sizes for decks include 2×8, 2×10, and 2×12, with larger dimensions providing greater strength and longer spans. To determine the appropriate span for your joists, it is essential to consult the local codes and guidelines specific to your area. Additionally, there are online joist span calculators available that can help you determine the optimal length for your deck joists.

By following the recommended joist spacing and sizing guidelines, you can ensure that your deck provides a sturdy, safe, and durable outdoor living space for years to come.

Joist SizeSpacing (inches on center)Maximum Span
2×81612 feet 10 inches
2×101615 feet 2 inches
2×121618 feet 0 inches

Beam Span Chart and Deck Support Beams

When it comes to designing a safe and sturdy deck, understanding the maximum span of your deck beams is crucial. The span of a deck beam refers to the distance it can safely cover without sagging or compromising the structure. To determine the maximum beam span for your deck, you can refer to a deck beam span chart or table.

A deck beam span chart provides guidelines for different species and sizes of lumber, helping you select the right beam for your deck. For example, a 2-2×8 Southern Pine beam can have a maximum span of 8 feet 6 inches, while a 2-2×8 Douglas Fir-Larch beam can span up to 9 feet 5 inches.

It’s important to note that these maximum spans are based on specific factors, including the grade and species of lumber, size of lumber, and the anticipated load. Typically, the load considered is a maximum live load of 40 pounds per square foot (psf) and a dead load of 10 psf.

Before finalizing your deck beam span, consult the beam span chart specific to your lumber species and size. This will ensure that your deck meets the necessary structural requirements, providing a safe and durable outdoor space for you and your family to enjoy.

FAQ

How far can a double 2×8 deck beam span?

According to the 2015 International Residential Code (IRC), the size of a double 2×8 deck beam can span up to 8 feet 9 inches when the deck joists are 6 feet long. However, when the deck joists are 8 feet long, the beam can span 7 feet 7 inches.

What if the joist length is not listed in the table?

If the joist length is not listed in the table, it is recommended to check with your local code official or use the shorter value in the table and assume the allowable span is 7 feet 7 inches.

How should the built-up beams be fastened together?

The built-up beams should be fastened together with a minimum of 10d nails spaced 16 inches on-center along both edges, and joints in beam layers must fall over posts. Beams are also allowed to cantilever up to one-quarter of the beam span between posts.

What is the typical spacing of deck joists?

The spacing of deck joists is typically 16 inches on center, but this can vary depending on local building codes and the installation instructions for the decking material. Some decking materials, when installed at a 45-degree angle, may require the joist spacing to be 12 inches on center.

How do I determine the span of my deck joists?

The size of the joists (2×8, 2×10, 2×12) will determine the span of the joists. It is important to consult the local codes and guidelines for your specific jurisdiction to determine the allowable span for your deck joists. Additionally, there are online joist span calculators available that can help you determine the appropriate length for your deck joists.

How do I determine the span of a deck beam?

The span of a deck beam is dependent on several variables, including the grade and species of lumber, size of lumber, and the load it carries. The International Residential Code (IRC) provides beam span charts that outline the maximum spans for different species and sizes of lumber. It is recommended to consult the beam span chart and follow the guidelines for your specific lumber species and size to ensure the structural integrity and safety of your deck.

Related Posts

error: Content is protected !!
0

Compare