What size joists should i use for decking

What is the proper placement? How far apart are floor joists placed? How do I keep them even? Your joist span will depend on the size of the lumber joists. See the below span chart as well as the local codes and guidelines for your jurisdiction. The larger the deck, the larger the joists. In typical deck construction, with a ledger on one side of the joist and beam on the other, the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above.

For best results, refer to our wood and composite deck joist span table. You can also use Decks. For conventional guardrail post installation bolted to the side of the framing, larger framing will provide more strength in the rails. For upper-level decks, 2x10 is recommended as the minimum size to use for strong guard post connections. Similar to guards, if stairs are to be hung from the side of an upper-level deck, 2x10 as a minimum is recommended, as it will exceed the depth of the first step.

Joist hangers are used to attach the ends of joists to the face of a beam or a ledger board. Be particularly cautious to follow an approved ledger connection method to the house.

If you identify a crown in the board, you should always install it upwards. The crown will likely eventually settle after completing construction and should settle in the proper position after drying. Most decks use 16" on center spacing for joists. Most decking is not strong enough to support longer spans than 16".

See the deck joist calculations below and study your local code. Deck Beam Spans: Distance a joist spans between a beam and a ledger or between beams, using No.

Joist: 2x6 If joists are spaced: 24" Span: 8'. Joist: 2x8 If joists are spaced: 16" Span: 13'. Decking boards span from joist to joist. Decking made of 2x4s or 2x6s can span up to 24 inches. If you will run decking at an angle, you might need to put the joists closer together. Again, it's important to know your local codes. Your local building department has regulations designed to ensure a strong and durable deck.

While a few requirements might seem dated or unusual, most are based on the following common concerns:. Save Pin FB More.

Credit: Keller and Keller. Span requirements ensure your deck won't sag or collapse during a party or under snow load. Codes specify maximum spans according to the type of wood used. A deck more than 2 feet or two steps above ground must have a railing.

Codes dictate how high the deck railing must be, as well as how far apart the balusters can be. Small children must not be able to climb it. Some codes require handrails, not just cap rails, for stairs. If you live in a high humidity area, consider installing under-deck ventilation as well. Keep it clean: Sweep the top of your deck regularly and remove any twigs, rocks or debris that gets jammed near the joist beams.

Inspect regularly: Finally, inspect your joists, beams and deck frame regularly, so you know if any issues arise and can address them before they turn into more significant problems later. Before You Install the Joists Decking joists are only one step in a multi-step deck building process. Before you install the joists, you must first prepare the deck area, dig footing holes and install the ledger and support beams: Area preparation: Always make sure the area in which you plan to build your deck is free of any tree root systems or utility lines and falls within local building codes.

If you want to do any landscaping to the area that will soon be your under-decking, do so before you begin your building project. Consider laying gravel or another type of weed barrier to keep landscaping to a minimum. Remember, depending on the height of your deck, you may not be able to access the under-decking area easily. Keep this in mind when making landscaping decisions. While a flat worksite is ideal, you can design a deck that accommodates gentle slopes as well.

Footing holes: You need to dig footing holes and fill them with concrete. These filled holes will act as the primary support for your deck posts — and, by extension, your joists.

Ledger: The ledger is the piece of lumber that you attach to the side of your home to support the deck frame. Always install a ledger to the structural foundation — never over siding of any kind. Many experts agree improperly installed ledgers are one of the leading causes of deck collapse and associated injuries. Take your time as you install your ledger, and avoid cutting corners. As always, remember to consult local building codes regarding ledger placement and installation.

Support beams: Once you have installed a ledger, you will add the remaining support posts and any applicable center beams before continuing to the joists. How to Lay Decking Joists for Composite Decking Now that you know more about decking joists, you can begin crafting the frame of your deck.

In addition to correctly-sized joist boards, you need: Galvanized joist hangers: Most decks require standard, face-mounting galvanized hangers, but some special cases — like living in a salt-air climate — might call for specialized hangers.

Choose your joist hanger according to the size and load capacity of your joists. Always purchase new hangers, rather than reusing or cutting old hangers to size. Only use hangers specified for joists and never attempt to make your own.

Corner brackets: Use corner bracket joist hangers for any degree joists in your deck plan. A chalk line reel: You will use a chalk line reel to pull a straight line across the rim joists. A pencil or piece of white chalk: You need a lumber pencil or piece of white chalk to mark your joint spacing on your ledger board before installation. A circular saw: Use a circular saw to cut lumber to meet your project dimensions, according to the recommend joist length and width.

Joist hanger nails are hot-dipped and galvanized. Be sure you have enough nails on hand to fill each hole on every hanger. Wood treatment or joist tape: Be sure to apply wood treatment or joist tape to every cut end of lumber to prevent moisture damage and warping.

On a small deck, the beams are sometimes incorporated into the joist framing. On larger decks, the beams support the joists from underneath.

The rim joists are the joists that make up the outside of the frame. If the deck is fastened to a house or other building, the board that fastens to the house framing is the ledger board.

The ledger board is another joist and is usually the same size lumber as the other joists. It rarely makes sense to use different size joists for the rims joists, ledger, and interior frame joists. If you use 2-by-8 joists for the rim joists or ledger, then use 2-by-8 joists for the rest. Learn how to determine the correct size for deck joists and what governs joist sizing. The minimum joist size is a 2-by-6, which may span up to 11 feet 7 inches without additional support if they are spaced just 12 inches apart.

Sometimes it will if the deck is small. On a small deck or stairway landing or similar structure, 2-by-6 joists make sense. On larger decks, determine the joist size using the charts to find the correct joist size. Look at the chart to the left and learn how to use it. This chart is for southern yellow pine SYP framing lumber and similar strength woods.

The table gives the maximum distance between joist supports which include beams and the ledger board. For example, if the joists are spaced 16 inches apart and are 12 feet long, the logical choice is a 2-by-8 joist which can span up to 12 feet 10 inches at this spacing.

If the joists were 15 feet long, then 2-by joists are required, which can span up to 16 feet 5 inches. Note that with these spans, no additional support is required under the joists.