Question: I want to build a pool deck for my round above-ground swimming pool. I’ve built decks before, but nothing round. Can you give me some tips?
Answer: Building a round pool deck out of rectangular lumber can be a challenge.
The first trick we use to build a pool deck is to use a post and beam deck frame then run the joists over it to conform to the round pool.
Cantilever layout.
When it comes to above ground pools, most of them are round, which poses some challenges as most building materials aren’t round or easily made round. And it’s not hard to see why some homeowners want a wood or composite deck around the pool because it’s easy to get in and out of the pool, and it’s just easier on the eyes overall. But it’s the deck itself that can be a challenge.
Determine if the joist cantilever will exceed 2-feet by running a string where the deck is to be built. Pull a string out the proposed deck width. Place the center of the string where the center of the deck is planned. Adjust the string so that the left and right ends are the same distance from the pool wall. Once they’re the same, this will show you the cantilever. If it exceeds 2-feet (at 20-feet wide, some quick layout tells me it’ll it be around 32-inches) then you may have some choices to make. You may be able to increase the size of the joists (2×10 > 2×12) or double them where they exceed a 2-foot cantilever. You may also be able to shrink the spacing (16-inches on center > 12-inches on center). Check with your local code official. Tip: When working with string, I mark the string’s center and ends with duct tape.
Build the frame.
Set your posts and beams parallel to the string. Remember to leave room for a 1×12 band joist between the joist ends and the pool rim to cover the ends of the joists and deliver a clean look. Using Western Red Cedar here is a good choice. You may need to kerf the back to help it bend more easily.
Set the joists.
Once your posts and beams are framed, you can mark the beam tops for the joist locations. Place each joist on layout. Do not nail yet. Use a level to plumb up from the pool to mark each side of the joist. Connect the dots. This will give you the angle the joist meets the pool at. Remove the joist, set your saw and cut it. (Note: the reason for doing this is that it’ll be easier to connect the band joist later).
Put the joist back on layout and fasten. Using a spacer block between the pool and the joist end a little thicker than your band joist will save lots of time here.
On the non-pool deck side, don’t worry about the joist length. Just run them wild over the beam. They’ll follow the pool radius. Once you have all the joists set, snap a line across the non-pool side and cut the joists straight. Or, you can leave the pool radius there too. It’d be cool, but you’ll have to make framing adjustments where the cantilever exceeds 2-feet.
Lay the decking and cut with a jigsaw. Install your band joist to cover the edges.
When is adult swim?
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