How to Build a Square Pool Deck for Above Ground Pools

Measure the height of your pool. Measure the length of the side where you wish to put the deck.

Divide the length of the pool by six, rounding up the resulting number. Divide the length of your pool by this number to get the distance you need between support posts. For example, if you have a pool 14 feet long, then divide 14 by 6. The result is 2.33. Rounding this number up gives you 3. Dividing 14 by 3 gives you 4.67 feet, the distance you need between posts.

Spray a mark on the ground at either end of the pool, where your deck will begin. Walk along that side of the pool and make additional marks, each as far from the last as the distance you need between posts.

Divide the width of your planned deck by six, rounding up the result. Divide the width by this number, which is the number of rows of posts your deck needs. This result is the distance needed between rows of posts.

Make as many rows of marks as there are rows of posts. Use the same method you used for the first row. Keep measuring the distance between the rows as you go, to make sure the rows are parallel to each other.

Dig a hole that extends below the frost line every place you made a mark. If the frost line is less than 1 foot deep in your area, make the holes 1 foot deep. Make the hole 8 inches in diameter, and use either a shovel or a post hole digger.

Add the width of the 2-by-8-inch boards to the thickness of the deck boards. Subtract the result from the height of the pool. Add the depth of the post holes to the result. This final result is the length of the 4-by-4-inch posts you must buy. For example, if your post holes are 2 feet deep, your pool 10 feet high, your deck boards 1 1/2 inch thick and your 2-by-8-inch boards 7 1/4 inches wide, your posts must be 10 feet minus 8¾ inches plus 2 feet, or 11 feet, 3¼ inches long.

Mix up a batch of concrete according to the manufacturer’s instructions. Because you will be working with small amounts, a wheelbarrow and hoe will be cheaper and easier to use than a cement mixer.

Place one post vertically in each hole. Wedge rocks into the hole to keep the posts upright. Check that the posts are exactly vertical by using a level. Fill the holes in with the concrete.

Cut two lengths of 2-by-8-inch boards that are each as long as the pool. Screw them together so that they form a 4-by-8-inch beam. Lay the beam on top of the posts in the row closest to the pool and screw them in place. Do the same for each of the other rows.

Cut the deck boards so each is 1 or 2 inches longer than the deck is wide. Lay them across the beams so they completely cover the beams. Screw them to those beams using two screws at each place the board crosses a beam.

Attach the prefabricated stairs. Make sure you buy the size appropriate for the height of your deck.

Stain the deck a shade that matches your house or deck furniture. Weatherproof the deck by applying a waterproof sealant according to the manufacturer's instructions.