Engineered Deck Beam
It is possible to increase your beam spans and eliminate footings and structural posts for your deck by using engineered laminated beams, heavy timbers or steel I girder beams. Using an engineered beam will reduce the number of posts blocking windows under a deck or may provide a clear span for a deck over a driveway. These beams are designed much stronger and more stable than standard dimensional lumber beams. It is possible to achieve spans up to 20 feet. Engineered beams must be treated for use outdoors.
Glulam beams are manufactured by gluing layers of dimensional lumber together. Parallam beams are manufactured by gluing together aligned wood stands and bonding them using a microwave process.
Large, solid sawn lumber timbers, referred to as “heavy timber” are available, but may be expensive to obtain in decay-resistant species if desired or necessary.
Your local lumberyard should be able to help you size and order engineered deck beams. Bring them a plan of your deck with dimensions showing the position of all your footings and posts. They will send your information to a design center where an engineer will specify the proper size engineered beam. They will also provide a report which will be useful in applying for building permits. Engineered beams are more expensive than standard deck framing materials but are usually the only option for projects that demand long beam spans.
Glue Laminated Timber Beams Spans
| Joist Spans | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Stress Class | Width | Depth | 6' | 8' | 10' | 12' | 14' | 16' | 18' |
Balanced or Unbalanced 20F -1.5E And Higher Grade Cedar | 3-1/2" | 9-1/2" | 12'-2" | 10'-6" | 9'-4" | 8'-6' | 7'-10' | 7'-4" | 6'-11" |
| 11-7/8" | 15'-2" | 13'-1" | 11'-8" | 10'-8" | 9'-10" | 9'-2" | 8'-8" | ||
| 16" | 17'-10" | 15'-5" | 13'-9" | 12'-7" | 11'-7" | 10'-10" | 10'-2" | ||
| 5-1/4" | 9-1/2" | 18'-0" | 16'-8" | 14'-10" | 13'-7" | 12'-6" | 11'-8" | 11'-0" | |
| 11-7/8' | 18'-0" | 18'-0" | 17'-6" | 15'-11" | 14'-9" | 13'-9" | 13'-0" | ||
| 16" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 16'-10" | 15'-9" | 14'-10" | ||
Unbalanced 24F - 1.8E Douglas Fir - Larch or Southern Pine | 3-1/2" | 9-1/2" | 13'-11" | 12'-1" | 10'-9" | 9'-10" | 9'-1" | 8'-6" | 8'-0" |
| 11-7/8" | 17'-5" | 15'-1" | 13'-5" | 12'-3" | 11'-4" | 10'-7" | 10'-0" | ||
| 14" | 18'-0" | 17'-9" | 15'-10" | 14'-5" | 13'-4" | 12'-6" | 11'-9" | ||
| 5-1/4' | 9-1/2" | 18'-0" | 18'-0" | 17'-1" | 15'-7" | 14'-5" | 13'-6" | 12'-8" | |
| 11-7/8" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 17'-0" | 15'-10" | 14'-11" | ||
| 16" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 17'-0" | ||
Balanced 24F - 1.8E Douglas Fir - Larch or Southern Pine | 3-1/2" | 9-1/2" | 13'-11" | 12'-7" | 11'-8" | 11'-0" | 10'-5" | 9'-11" | 9'-7" |
| 11-7/8" | 17'-5" | 15'-10" | 14'-8" | 13'-9" | 13'-1" | 12'-6" | 12'-0" | ||
| 14" | 18'-0" | 18'-0" | 17'-4" | 16'-3" | 15'-5" | 14'-9" | 14'-2" | ||
| 5-1/4" | 9-1/2" | 18'-0" | 18'-0" | 17'-4" | 16'-3" | 15'-5" | 14'-9" | 14'-2" | |
| 11-7/8" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 17'-6' | 16'-9" | ||
| 16" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | 18'-0" | ||
Assumes 40 psf live load, 10 psf dead load, L/360 simple span beam deflection limit, cantilever length/180 deflection limit. Glued laminated timber shall be naturally durable or preservative treated with an oil-borne treatment in accordance with AWPA U1.
How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
Roof Top Deck Construction
Rooftop decks transform otherwise wasted space into beautiful planes for entertaining, dining, relaxing and even gardening. The views will make your deck the talk of the neighborhood and draw frequent guests to your home or business.
How to Use a Triple Deck Beam to 6x6 Post Connection
Learn how to use a post beam connector to attach a 3-2x10 beam to a support post for a deck when there isn't enough material on the post to create a notched connection.
How to Install Decking Over Existing Concrete Slab, Patio, or Porch
Discover the best techniques to build a deck over concrete, ensuring proper drainage and stability, while creating a beautiful outdoor space.
6 Best Alternatives to Wooden Decking
While wood decking was previously considered the standard material for building a deck, that’s changed. Homeowners have been exploring and embracing different types of materials, and the availability of alternative decking materials has grown significantly.
Anatomy of a Deck
A comprehensive guide to help you learn the names and understand the functions of every part of your deck.
More Helpful Resources
Explore Articles by Topic
Footings
Information related to installing frost footings for decks
Framing
Learn structural framing methods
Decking
Learn about wood and composite decking materials
Stairs
An in-depth look at the complex issue of how to build stairs
Railings
How to install guardrails and handrails to meet IRC code
Features
An overview on water drainage, benches, planters and lights
Design
The basics of deck design
Planning
Learn about permits and working with contractors
Porches & Patios
Build a covered deck to enjoy all seasons
Ledger
Proper attachment techniques
Care
Maintain your deck to maintain your investment
Materials
An overview on water drainage, benches, planters and lights
Why is Joist Protection so Important for Your Deck?
If you’ve ever seen a piece of wood left out in the weather for any period of time, you know what happens: decay. Whether through wet rot, insect damage, or mildew, the fibers begin to break down.
How to Install Deck Girder, Cantilever or Drop Beams
Learn about the pros and cons of installing a cantilever, girder or drop beam to support your deck joists. This method allows for a notched post-to-beam connection.
Building Your Deck For A Hot Tub
Learn how to build a deck to properly support a hot tub or spa. Hot tubs are very heavy. Never place a hot tub on a deck that wasn't designed for the additional load.
What to Consider When Building A Wrap-Around Deck
Looking to add a wrap-around deck to your home but unsure of what the process involves? Check out this guide to learn more about top considerations when building a wrap-around deck.
How to Install Decking Over Existing Concrete Slab, Patio, or Porch
Discover the best techniques to build a deck over concrete, ensuring proper drainage and stability, while creating a beautiful outdoor space.
Deck Replacement & Repair Costs
Not sure whether to fix your old deck or tear it down? This guide explores the costs and pros and cons of repairing vs replacing your deck.
Explore Articles by Topic
Footings
Information related to installing frost footings for decks
Framing
Learn structural framing methods
Decking
Learn about wood and composite decking materials
Stairs
An in-depth look at the complex issue of how to build stairs
Railings
How to install guardrails and handrails to meet IRC code
Features
An overview on water drainage, benches, planters and lights
Design
The basics of deck design
Planning
Learn about permits and working with contractors
Porches & Patios
Build a covered deck to enjoy all seasons
Ledger
Proper attachment techniques
Care
Maintain your deck to maintain your investment
Materials
An overview on water drainage, benches, planters and lights