Planning and building a DIY deck frame is a great way to build a personalized deck you can be proud of. While building a deck frame isn’t as simple as nailing a few boards together, it is an attainable DIY project - with the right knowledge and guidance. That’s where DecksDirect comes in. Check out this guide to plan your outdoor oasis with the right deck joist spacing and joist spans.
Table of Contents:
- Why Do I Need To Plan My Deck With The Right Joist Spacing
- DecksDirect: Your DIY Deck Project Guide
- How to Plan Deck Joist Spacing & Joist Spans
- Terms To Know
- What Is A Deck Joist?
- How Far Apart Should You Space Deck Joists?
- How To Make Sure You Have The Right Joist Spacing
- What's The Maximum Deck Joist Span?
Why Do I Need To Plan My Deck With The Right Joist Spacing?
It’s essential to plan your joist spans and joist spacing correctly - this makes sure your deck will meet building codes and makes it much quicker and easier to get the building permits you need to get started on your deck project. More important than all that, though: deck joist spacing and span requirements are based on tried-and-true industry standards, and they’re in place to make sure your deck is safe and structurally sound for you, your family, and your friends.
DecksDirect: Your DIY Deck Project Guide
At DecksDirect, we know you’re capable of planning and building your own deck frame. And we want to give you the tools to make it easier! Here are two resources we provide to help you get started:
DecksDirect’s Deck Framing Guide: To learn more about all the parts and layout of a deck frame, check out our How To Frame A Deck Guide, written by experienced decking professionals.
Personal Deck Planning Guidance: Unlike your local hardware store, we don’t sell you deck parts and send you on your way. We staff a team of experienced deck project planners who are available by phone to help you plan your project from start to finish. Give us a call at 1-888-824-5316 to work with a knowledgeable deck planner to create a deck project perfectly suited to your vision and your experience level.
How To Plan Deck Joist Spacing & Joist Spans
Planning your deck joist spacing requires forethought and knowledge of common terms and concepts.
Terms to Know
Before we discuss deck joist spacing and spans, understanding the basic terms is essential. Here are some concepts you need to be familiar with.
What Is A Deck Joist?
Joists are structural elements that make up the framework of the deck beneath the deck’s walking surface. Joists attach to a ledger board using joist hangers and run the entire length of the deck, perpendicular to the house, which is the most common deck joist layout.
Deck joists, like the rest of your deck’s frame, can be made from a few different materials. Traditionally, deck frames were built with pressure-treated lumber. But new steel framing options are becoming more and more popular for their strength and durability. Steel framing also supports longer maximum joist spans, and steel framing parts are more consistent in size and straightness, making things much easier for DIY builders.
Other terms to know include:
- Joist Span: the length of your joist from one end to the other
- Joist Spacing: the distance between each joist, measured from the center of one joist to the center of the next joist. (This is called on-center spacing).
How Far Apart Are Deck Joists?
The short answer: deck joists are typically spaced either 12 or 16 inches apart, on center. (On-center means the length from the center of one joist to the center of the next joist, rather than a gap from edge to edge).
The maximum joist spacing you can use for your frame will depend on a few factors:
- The size of your deck joists
- Your framing material
- Your maximum joist span
How To Make Sure You Have The Right Joist Spacing
To make sure you’re planning your deck frame with the right joist spacing, there are two sets of standards you should check:
- Your deck material’s standards
- Local building codes
1. Joist Spacing for Composite Decking
Every deck board manufacturer puts its decking material through in-depth independent testing to find the right joist spacing. In almost every case, composite decking manufacturers have found that 16-inches on-center is the maximum joist spacing for their boards. You can find joist spacing requirements in the installation instructions for your deck boards.
One note: that 16-inch spacing is based on a traditional deck board pattern, with boards installed perpendicular to joists. If you’re installing deck boards at a 45-degree angle to your joists, you’ll need to tighten up your joist spacing to 12-inches on center.
Joist Spacing for Trex
Trex recommends deck joist spacing of 12 inches or 16 inches on center, depending on the deck board size, although it says 24 inches is acceptable for decks with 100psf or less.
Timbertech Joist Spacing
TimberTech's suggested deck joint spacing is 16 inches. However, its MAX deck boards allow 24 inches on center. The company recommends using 12 inches on center if you want a more rigid feel.
2. Local Building Codes
Local building codes can sometimes have different joist spacing requirements. That’s why we always recommend checking in with your city’s building department to make sure your plan meets any local or state requirements.
What's The Maximum Deck Joist Span?
Deck joists have different maximum span lengths depending upon the size, spacing, and framing material that you're creating your deck with. Here's a helpful chart covering the most popular wood framing species and their maximum allowed spans:
The Power of Steel
Steel framing is not only lighter and longer-lasting than wood - it also allows for much longer joist spans.
Below, you can see a comparison between 2x6 joists made of three different wood species and 2x6 steel joists from Fortress Evolution Steel deck framing in two different gauges of steel. The maximum allowable spans are significantly longer with steel joists. In fact, a 2x6 steel joist will provide the strength of roughly a 2x10 wood joist when it comes to allowable joist spans.
To learn more about planning your deck with steel framing, give us a call at 1-888-824-5316. We've got a team of deck project planners ready to create a plan that helps you create a stronger, safer deck with the best framing materials possible.
Frequently Asked Questions About Deck Joist Spacing & Spans
As a trusted supplier, DecksDirect frequently fields questions about deck joist spacing and spans. Here are some of the common questions we receive.
How far apart are floor joists?
The floor joists for a deck are typically spaced 16 inches or 12 inches on center, although 24 inches may be allowable under certain circumstances. Check with the manufacturer for the recommended spacing.
How many joists do I need for my deck?
The number of joists you need depends on your deck's width. Generally, you need to divide the width by your chosen on-center spacing (typically 12 or 16 inches) to arrive at the correct number of joists.
Can I use 2x6 for deck joists?
Yes, you can use 2x6 boards as deck joists, but you must take special care with your deck joist spacing and spans.
How far can a 2x6 deck joist span?
The span of a 2x6 deck joist depends on your deck joist spacing and material. For instance, a 2x6 redwood or cedar joist can span eight feet at a spacing of 16 inches. On the other hand, a 2x6, 16- or 18-gauge steel joist can span 16 feet, 4 inches if the spacing is 12 inches.