I love ping pong, but our house is too small to hold a table...so I built a concrete Ping Pong table for my yard. Well--I guess I should say I built an outdoor ping pong table with the top poured from concrete. The base is red cedar.
I started with this site. It has a great strategy for ensuring a perfectly-smooth top, and the owner was very responsive to a couple questions I floated in his forums and on YouTube.
Everything else was improvised.
I built the molds out of melamine. I poured the top in two halves for weight reasons (each half is nearly 450lbs each when finished). This was a good decision. I ran into a snag here. Because ping pong tables are 5x9, each half needed to be 4.5x5-ft. I wasn't able to get a big enough piece of malamine for a one-piece mold, so I had to scrap two pieces together. This meant my tabletop would have a seam in it--a no-no for a playable ping pong table. I didn't have much of a choice, though, and decided I would just sand the seam out. If I had to do it again, I would have started by finding an old ping pong table top to use as my mold. The texture is melamine-like to begin with, and it would have saved a lot of work down the road.
I wanted a relatively thin look, so I opted to pour the tops just under 1.5 inches thick. I was worried about strength at this thickness. I needed to use beefy-ish rebar. This was challenging. It meant I had zero room for error when it came to placing rebar. I used Pig Wire This is a picture of once the mold began to come off. What you can't see is that where I scrapped the two pieces together, it collapsed a bit. This meant the 'seam' I was planning on turned into a 'ridge'. This was not even close to acceptable. This meant a ton more sanding, and the purchase of some materials (a set of 4-in diamond sanding pads and an circular sander), that I wasn't planning on. Not only that, but when I began sanding down, I hit rebar by one of the ridges and had to stop. The table still has a small ridge in one spot, but it is very near the net, so almost entirely out of play.
Fitting the base
Built the base out of weather-resistant red cedar. I was very concerned about strength here. Decided to make it with six legs so that the halves had something solid to rest on all all four of their corners. Built the base 4x8, allowing for some overhang (but not too much) on each side.
I Assembled the base with 4-inch Spax lags. This worked well. They were plenty strong, and the design allowed the base to stay solid while still staying relatively light (at least in comparison to the tops). Added a bottom rail on the inside for strength and looks.
I got stuck at this point. I had a couple days of sanding and tweaking the top, but the three pieces sat in my garage untouched for a few days while I waited for help. It took four men to move the halves into place, and we could have used five.
This is the table in place on the patio under the pergola. There is a bit of an uneven pattern to the cement caused by mixing in small and inconsistent batches. If I did it again, I would rent a drum mixer and pour all of my cement at once. I would save quite a bit of work. I think this will even out when I stain and seal the top, but the thing is playable--and it plays well!
I'm posting this 4-months after the build. Since these photos the top has been cleaned, stained, and I've met a neighbor who regularly comes over and kicks my ass. It's a good arrangement.
Things I would change? Absolutely.
If I did it again I would NOT build the form. Because a ping pong table measures 9x5, a 4x8 sheet of melamine--while a wonderful texture for pouring cement--needs to be heavily modified. As it was, I needed to rip a piece of melamine into strips and scab them on to a larger piece, creating two identical half-molds that measured 5x4.5. I then needed to perfectly align, caulk, and smooth the joint so I didn't end up with a ridge. It took a long time, and then when I poured my concrete, it collapsed and I ended up with a ridge anyway. This was the single most frustrating part of the process.
If I did it again--and I'm kicking myself for not thinking of this the first time around--I would start the project by purchasing a used ping pong table off Craigslist. Basements all over America are home to long-abandoned tables that have become a repository for Hunting clothes and boxed Christmas decorations. By purchasing a used table (or very probably acquiring one for free), I would have had perfectly-sized, perfectly-textured molds. My only job would have been building the walls and caulking.
I would never build another table without taking this step first.
I mixed all of my concrete in individual batches. I used a concrete paddle, a power drill, and a five-gallon bucket that smelled like pickles. This worked out well enough, but I underestimated how much work it would be.
If I did it again I would rent a concrete drum. There is an equipment rental place 2-miles from my house that rents these for something like $30/day. This would have not only saved my hands and back from a couple hours of good-old-fashioned manual labor, but also would have ensured an even consistency and pour. This would have been well worth the added cost.
This thing is heavy.
Now, I'm not an idiot. I knew it would be (and if I didn't know initially, I would have figured it out after everybody and their brother telling me it would be when I told them about this idea). Still, I was amazed at how heavy this turned out in practice. I'm not sure how I could conceivably lighten the top. Since the build (just in time, fellas), people have said that I should have filled the center with styrofoam.
I've also had several people suggest using a concrete hybrid--something along the lines of a concrete mixed with a plasticizer. This sounds promising, but--when pressed--the people who suggested this have never been able to give me any more information other than that they 'are pretty sure such a thing exists.'
The final table ended up running me ~$800. This is--admittedly--expensive.
If I did it again, though, I would be able to cut that cost in half, with most of the savings coming from a change in cement.
When building this, I was paranoid about getting a smooth top. As a result I sprang for a brand of concrete specially formulated for concrete counter tops. While the results were excellent, the product, at $15/bag, was overkill.
If I did it again, I would have used Quikrete 5000, a versatile, cheap mix. Knowing what I know now, I feel I could get the same results while trimming my largest expense by 2/3.
I would build this table again in a heartbeat. It was a fun, simple-ish project, and I'm proud of the end result, flaws and all.
It's a unique piece that's pulled my friends and family into the backyard, and which has allowed me to make new friends with people in the neighborhood.