How to Build a Simple 24 Foot Deck

Decks can come in all shapes and sizes. However, the basic form of a deck is universal; there are footers, posts, frame, decking boards and railing. With a handful of tools and some basic construction knowledge, building a deck can be a simple task completed on a long weekend. For the purpose of the article we'll look at a basic deck that is freestanding, 24 feet long, rectangular and with one set of stairs. However, before you get started check with your local city or municipality for coding and inspections.

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Decks all have the same basic structure.

Planning and Layout

Step 1

Meet with a building planner at your local lumber yard to determine the close estimate of material you will need and help you with information on codes and inspections for your specific area.

Step 2

Call for utility mark-outs before digging.

Step 3

Plant a stake where a corner will be. Tie string around the stake. Measure 3 inches shy of 24 feet (23 feet, 9 inches—this will be explained later) moving toward the next corner and mark it with a stake. Wrap the string line around that stake a few times and move toward the next corner.

Step 4

Check for square of layout before you continue. Start in the short side of your new 90 degree angle and measure up 6 feet and make a mark. Return to the corner and measure 8 feet down the far side and make a mark. Measure from mark to mark. This measurement should be 10 feet but may need to be adjusted in or out to square the angle. Set your stake. Repeat this for each corner until your outline has 4 right angles.

Step 5

Mark a spot with either spray paint or a shovel where the first stake is located. Measure every 4 feet along the string line in each direction marking each interval with the paint or shovel. These marks indicate where the posts need to be placed.

Step 6

Dig a hole at each mark at least 2 feet down and at lease twice the size of the post. This may vary depending on codes and frost lines in your area. In some areas these holes will need to fit the concrete forms as well.

Step 7

Set posts in holes (and forms if necessary) and mix concrete and water with a hoe in a mixing tub or mixer. Pour concrete in holes until the hole/form is filled.

Step 8

Level each post and tack a 2x4 or scrap lumber to the post and a stake driven into the ground to keep it solid until the concrete sets. Leave posts and concrete to cure overnight.

Framing

Step 1

Mark a line on a post at the height that the top of the deck will be (this will be determined by style and possibly codes) and subtract 7 1/2 inches and make a new mark for the ledger board (7 1/2 inches is the height of the decking board and the 2 x 6 frame). From this mark use the level to get a straight line to all the posts (due to the uneveness of the ground a measurement cannot be taken at each post.

Step 2

Attach the ledger board to the posts (along the 24 foot length) with 3 inch decking screws or spiral shank nails first. Use the 12 foot pressure-treated 2 x 8s on the outside to show fewer joints. The 8 foot pressure-treated 2 x 8s will go on the inside of the posts creating two lines of sandwiched posts. Double check level as you go.

Step 3

Drill two 1/2-inch holes diagonal to each other per post and tap carriage bolts through. Insert them so that the heads will be showing on the outside and the hardware will be on the inside. Tighten bolts with rachet/socket until the carriage head or nut becomes flush with the ledger board.

Step 4

Dedicate the four 2 x 6 x 12 foot boards to become band boards so that there are two lengths of 24 feet. These band boards will act as a layout marker for the deck joists as well as an outside frame to hide joist ends. Lay the boards in two lines butted up to each other so that you can lay out both band boards at the same time. The band boards are the exact 24 feet and will stick past each outside post by 1 1/2 inch, which is the width of a 2 x 6 board. This way the posts are inside the framework but the total width of the deck is 24 feet.

Step 5

Measure 1 1/2 inches from the beginning and make a mark on each board for the width of the outside joist. Measure over from the end 15 1/4 inches and make a mark followed by an X (this denotes that the joist starts at 15 1/4 inches and covers the X so that the center of the joist will fall exactly on 16 inches). Continue this pattern of marking a line 3/4 of an inch prior to each multiple of 16 inches until you reach the end of the board where the last mark will be 1 1/2 inches from the end as in the beginning.

Step 6

Attach band boards to each post using three 3-inch screws or spiral shank nails to each post. Band boards will set on top of the ledger boards and overhang the outside posts by 1 1/2 inches.

Step 7

Insert joists between band boards at each of the layout marks. These will also rest on the ledger boards with the exception of the two outside joists, which will get attached to both the band boards and the posts. Use three 3-inch screws or spiral shank nails to attach the joists to band boards and posts.

Decking and Railing

Step 1

Attach decking to floor joists with 2-inch screws or spiral shank nails. Use three nails to each joist. Cut out any notches or holes to work the decking around the post; this makes a nice finishing touch and keeps the posts intact for hand rail uprights. Start with a full decking board and then stagger each consecutive row by four feet. This helps break up joints and give more strength to the deck.

Step 2

Rip down the final row of decking boards with the circular saw (if necessary) to the proper width, allowing for some overhang if desired. Attach with screws or nails.

Step 3

Cut each post to the proper height from the top of the deck (minus 1 1/2 for top railing). This is generally around 3 feet but may be specific in some areas.

Step 4

Attach a 2 x 4 parallel to the deck, flush with the top of the posts and at the junction of the decking and the posts using 3-inch screws or nails. Remember to leave a 4 foot section open between two posts for the stairs.

Step 5

Attach the 2 x 6 top rails to the top of the post, flush with the outside of the post and covering the 2 x 4 edge using 3-inch screws or nails.

Step 6

Cut a spacer block to the width that each railing upright needs to be. This is generally about 3 inches plus or minus 1/4 inch, but check with your local codes.

Step 7

Level the first upright and begin attaching with 2-inch screws or nails. Space them with the block and check level every five or six uprights; adjust accordingly.

Stairs

Step 1

Cut a 2 x 8 into two 4 foot, 3 inch sections and mark a line at 1 1/2 inch on each end. Again measure over 15 1/4 inches, drawing a line followed by an X and repeat (this layout will give you a 4-foot wide set of steps).

Step 2

Attach each step stringer to the 4 foot, 3 inch 2 x 8 using 3-inch screws or nails. Attach the 2 x 8 to the flat side of the stringer just past the angled edge (opposite to the upright of a tread).

Step 3

Place the stair form on the face of a band board or outside joist so that the outside stringers line up just outside of two posts (this saves digging new posts for stair railing). Level treads parallel to the ground and whole stringer set up with the deck. Use patio block to set the bottom solid. Attach stairs with 3-inch screws or nails and 3-inch lag bolts.

Step 4

Dig two more holes for posts near the bottom of the steps for hand rail post. Set the posts, level them and pour concrete into the post holes. Attach the posts to the stairs with carriage bolts—you don't have to wait to for the concrete to set unless it's necessary for inspection.

Step 5

Cut the bottom posts, top rails and 2 x 4 rails at the same angle that stairs are laid out. Attach 2 x 4 side rails flush with the top of the post using screws or nails. Attach the top rail to the posts but this time flush with the outside edge of the 2 x 4.

Step 6

Attach uprights so that they are level vertically and spaced properly. Check with local codes for additional requirements on stairs and railings before final inspections.