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I have two 3" x 3" square holes on a sports court. They are around 2' deep. They take two long poles that support a net.

When the poles are not in the holes they fill with water when it rains (mosquito breeding area) and are a trip hazard.

Question: How can I cover these holes where the cover will be flush with the surface of the court?

What I'm currently thinking of doing, not sure if it's the right approach: Buy a 3x3 piece of lumber (surprisingly hard to find) and cut 2' lengths from it and stick those in the holes.

Problems I see with that:

  • Home Depot and Lowes don't have 3x3 wood listed on their sites.
  • When it gets wet I am guessing that it would swell and be difficult or impossible to remove. (I'm also guessing that there's something I could treat it with to make it water proof.)
  • It would be difficult to get out even when dry. (Thinking that a small hole in the middle of the end with a sunken eye screwed into it would allow me to lift it.)

If you think that my current approach of putting a block of wood in there is the right approach then I'd love to hear suggestions about how to do it to solve the problems that I forsee. Otherwise if you have a better idea to solve this...


My first thought is square flush tubing plugs. they come in all sizes, for tubing up to like 6".

Check out this web site: Mocap square tubing plugs

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Should be pretty easy to pry out with a small tool when you need to. They are not advertised as perfect seals to keep out water, but unless an area depression causes standing water right by the hole, I bet they would do a pretty good job.

  • 1
    If the sizes available are not exactly perfect, I bet you could trim the little friction fins that hold it in, on an over-sized one, to make it fit. Apr 28 '16 at 2:20
  • 1
    These on a treated 2x2 leg might be just the ticket.
    – isherwood
    Apr 28 '16 at 18:22

I would not use wood. I would fill the hole with a "thing" but I would not make the "thing" of wood. Since you seem to have steel sockets, use a section of hollow steel tube the same size as your posts (thus, a slip fit in the holes), but shorter, possibly with a square of rubber on the top over a welded-on steel plate. The rubber square would cover the hole or two in the steel plate that you'd use to hook them out of the holes in the ground.

Cheapskate quickie alternative - buy a 1-1/2" XPS styrofoam insulation sheet. Cut 3" wide strips. glue them together with a waterproof, foam compatible glue (PL300 is one, IIRC, there are surely others) to make a 3" square (or whatever size it takes for a light friction fit.) Glue some sunlight and rot resistant (polypropylene is one choice) string into the joint, run all the way to the bottom, possibly threaded into some holes. The "rubber flap idea" would still be good for covering that string and the top surface of the foam - the string should have a loop up top so it can be used to pull the foam block out. Depending how long this is supposed to be in use and the use of the surface when it's in place, some sort of light caulking or rubber cement to keep the flap in place might be appropriate. A loose fit will float, which is why you want a friction fit, but not one that makes you break the string.

  • I think your first idea would be mighty difficult to get right in the real world, but your second one about the styrofoam is ingenious! Apr 29 '16 at 3:41
  • The first one is what's commonly seen in any commercial setting with sockets in the ground. It's easy enough if you have (or hire) the right tools and skills. The second will be a lot easier for the typical non-welding homeowner.
    – Ecnerwal
    Apr 29 '16 at 11:57

I'd use treated 2-by lumber to create a simple cap-and-post device.

Cut squares the size of your opening on a miter saw and give the corners a small bevel to ease fitment.

Measure the depth of each hole and subtract the thickness of your cap material (1-1/2" in this case). Cut lengths of 2x2 lumber (or split 2x4s) as legs. Fasten the caps to the legs with decking screws. Drop them in the holes and be happy. You could drill a 1/2" hole near one edge of the caps to facilitate removal, say with a wire hook.


I would try to create a top seal that is slightly larger than the hole (maybe 3.5x3.5) with beveled edges, screwed into a block slightly smaller than the holes. A firm, but flexible plastic, maybe. Aluminum if you cannot work out the plastic. I would then seal under the overhanging flange with exterior caulking. Removal by cutting the seal and, if necessary, screwing an eye into the top to pull.

If you absolutely cannot have a raised surface, get a 4"x4" by 2" piece of pressure treated post (actually 3.5"x 3.5"). Rip it down to 2 3/4" x 2 3/4". Insert in hole and caulk (exterior rated) edges. Top coat with silicone seal, liquid rubber or other waterproof topping. Remove by slicing around the edges and prying out (using a center eye if necessary).


Following the theme of the question,

If you want to use wood, perhaps for simplicity, I would get like a 2x2 pressure treated deck wood and make a stake that is short by the thickness of a piece of wood decking (1/2" I think but I didn't go measure might be 3/8" take your own measurement). Cut the decking material to fit the hole as tightly as you want. Then using galvanized or stainless steel screws about 2" long attach the two pieces.

Put the stakes in the hole before screwing. Find something to use as a shim temporarily (a small wad of masking tape would work great) to keep it centered, then add your wooden decking top piece. Pre-drill one screw hole through both pieces placed correctly, put the screw in, then pre-drill a second screw hole and add a second screw. Resist the urge to drill both together, I guarantee they won't line up as well, get one screw in then add a second. Be sure to pre drill a slightly smaller hole the entire screw depth or either wood piece may split.


The idea you have is a good one, but you will probably not have any luck finding dimensional lumber that fits your needs exactly.

Instead of looking for a 3 x 3, you can just buy a pressure treated 4 x 4, which is only really 3.5 x 3.5, and rip it to size using a table saw. Since the depth of the holes is only approximately 2' deep, you should have enough material for both holes using one piece of lumber. Once you have cut the wood down to the correct size to fit the hole, insert the wood into the hole until it reaches the bottom. Mark the depth, and cut it to length, and re-insert it into the hole. When you are done, you will have a plug that fits perfectly. One thing you want to do is cut the wood slightly smaller than the opening of the hole so you will be able to remove the wood later. If it is a tight fit, then the wood will expand too much from being exposed to moisture, and you would have a hard time removing it.

When it comes time to remove the plug, you can screw in an eye hook to the end and lift it out by hand.

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