How to Build a Deck Around an Above Ground Pool

Laying Out the Deck

Measure your pool. Make sure you have an accurate record of the diameter and the height of the pool. You will need this to determine the dimensions for the deck.

Decide on the dimensions of your deck. Plan plenty of width between the edges of the pool and the perimeter of the deck so that swimmers can walk comfortably.

Obtain any necessary permits. Take your rough plan to your local building department or ask a building inspector to come to your home. The inspector will give you advice on regulations for stairs, handrails, guards and other elements that may be subject to municipal codes. Draw up your final plans based on the inspector's recommendations and requirements, and get all necessary permits before you begin building—especially electrical permits, if that will be part of your new deck.

Choose what type of decking you want to use. Pressure-treated wood is generally fine but you may also prefer a composite material.

Lay out the deck around the pool using stakes driven into the ground. Pull a string line from the corners to establish the outside perimeter of the deck. For our example, we'll assume a 21-foot pool. Mark the location of an interior post about 1' (30 cm) from the edge of the pool. Locate the next post 4 feet (1.2 m) away from that point. The perimeter edge of your deck shouldn't be more than 4 feet (1.2 m) away from a post. To find out how many interior posts you will need, add the distance from pool to post, multiply that by 2 and add it to the diameter of the pool, then multiply the total by pi (3.14159). That will give you the circumference. Now divide that number by 4 to get the number of posts you will need. In this case, the post is 1 foot (0.3 m) from the pool, and the pool is 21 feet (6.4 m) in diameter: (1x2 + 21) * π ÷ 4 = (23 * π) ÷ 4 = 18.06. You will need 18 posts for the inner ring.

Installing the Posts and Piers

Install the precast concrete pier footings on the top of the ground. To support your deck, purchase precast concrete piers with sockets that accept 4" x 4" treated wood posts. Most places in the U.S. allow this type of construction, but verify with a local inspector that this is acceptable. Set them up as follows: Place the piers at the exact locations you marked for your posts. Check two sides of the pier with a level. Keep adjusting the ground until the footing is level in both directions.

Set a 4" x 4" post into the opening in the top of the concrete piers. Lay a 4-foot level across the top of the pool cap and use the level to mark a line on each of the 4" x 4" posts.

Remove the posts from the piers. Below the line that you just drew, measure and draw another line. The distance between the 2 lines should equal the sum of the width of the pool cap plus 1-1/2inches for the 2" x 6" decking, 5-1/2 inches for the 2" x 6" floor frame, and an additional 1/2 inch for expansion. Cut the posts to the length given by the second line that you marked. Place the posts back inside the piers.

Install the Deck Framing

Install 2" x 6" treated deck supports around the perimeter of the pool. The deck supports should be screwed into the side of each interior pier that faces the pool. Screw the supports to the interior piers using 2-1/2 inch deck screws. Use a level to make sure that the supports are level. Also, use a square at the corners to make sure that the supports are square.

Install another set of 2" x 6" deck supports to mark the outside perimeter of the deck. Screw the supports to the outer side of the exterior piers using 2-1/2 inch deck screws. Confirm the supports are level and square, and make adjustments as needed.

Toenail joist hangers vertically to the interior of the supports using 3-1/2 inch 16d galvanized nails. Hang one joist hanger every 16 inches on the insides of both deck supports so that the joists will be perpendicular to the supports. The midpoint of each joist hanger should be 16 inches on center. This means the middle of the 2" x 6" joist board is on the 16 inch mark.

Place 2" x 6" treated wood deck floor joists into the joist hangers. Toenail the hangers to the joists using 10d galvanized nails.

Install 2" x 4" diagonal braces between the piers if the deck is more than 30 inches high. The braces should run between the piers from interior to exterior as well as parallel to the sides of the pool.

Install the Guard Rail

Install 4" x 4" precut railing posts around the perimeter of the deck. The precut posts should have a notch at the base that fits against the edge of the deck, and they may have a decorative top. Use 3/8-inch x 4-1/2 inch lag screws to secure the posts to the supports. The posts should be installed at every point where a joist meets the supports. Make sure to leave an opening for your stairs.

Slip 2" x 6" boards between the posts. The top of the 2" x 6"'s should be flush with the base of the decorative element. Pre-drill a pilot hole at the desired angle, then attach the boards with 2-1/2 inch deck screws. You may attach 2" x 6" joist hangers first to make the boards easier to install.

Cut a 2" x 4" to the length of the board that you just installed between posts. Lay the wide side of the 2" x 4" against the 2" x 6" and screw it to the 2" x 6" using deck screws. The 2" x 4" acts as a cap for the railing.

Install 2" x 2" balusters with a 45-degree beveled base to enclose the guardrail. Use a level to plumb each baluster. The balusters should hang parallel to the posts and should be positioned at 4 inch intervals. The beveled in should be at the bottom facing outward. Screw the baluster into the 2" x 6" railing at the top and into the floor joist at the bottom.

Build the Stairs

Set the bottom edges of 2 precut left and right stair stringers on top of concrete patio blocks. The blocks will keep the stringers from wicking up moisture from the ground.

Check the stringers to ensure that they are level.

Screw the upper ends of the stringers to the floor joists on your deck.

Add interior stringers to support your stair treads. You will need 1 stringer for every 2 feet (0.6 m) of stair treads. Unless your stairs are more than 4 feet (1.2 m) wide, you will only need the 2 exterior stringers and 1 middle stringer.

Screw 2" x 12" boards to the stringers to finish the stairs.

Build a gate. If young children have access to the pool area, build a gate to prevent them falling in. Install a lock if children will be playing unsupervised near the pool.