This project seemed like a success immediately after we completed it, but the following week the weather brought rain and the table started degrading. Because it didn't hold up to the weather the way I had hoped, I considered it a failure and I never published the project until now. Since Instructables is now hosting the "Epic Fails" contest, I decided to dust this project off and enter it in the contest.
We had very strong winds one day and the top for our patio table shattered. I looked around for options to replace the top, but a custom piece of tempered glass is very expensive and I can't remember who made this table. Most of the sites I found said a manufacturer replacement top would still cost close to $200. I could buy a new table for that much, but the rest of the set is still in good shape. I decided to try to make a new top myself.
Everything cost about $60 for materials and it took about a day and a half to finish. Your cost may be higher if you don't have trowels, floats, sponges and buckets.
Step 1: Materials
I read a lot of posts on the internet with suggestions about what to use for the tabletop. Some people said cement board would work, others said it wouldn't hold up in winter. Some people said marine plywood would do it, but I don't have a convenient place to buy that where I live, and I was trying to do this cheaply. The table top is nearly 4' wide, so cement board was out of the question because I could only find them in 5'x3' sheets. I decided to go for 3/4" plywood since it is thick enough that it shouldn't flex under the weight of the tile. This should prevent the grout and tiles from cracking.
Step 2: Tabletop
Rather than cutting the plywood to fit inside the frame as the glass had, I decided to cut a few filler strips from 2"x4" lumber and screw the top to the legs through the filler strips. This way, I have a slightly larger table that is perfectly square and easier to tile. I dropped a plumb weight through the umbrella hole in the table frame and drilled a whole through the top with a hole saw.
Step 3: Tiling
I bought the cheapest tiles I could find at the hardware store. These were nearly 16" square floor tiles and the box held enough for 16 square feet of floor space. I also bought 2 sheets of tiny glass tile mats to use as edge banding.
I bought a big bag of dry thinset mortar. If you mix it yourself, it is much cheaper and you can use as much or as little as you need. After I finished tiling the table, I had more than half a bag of mortar leftover for the next project or future repairs.
I could have used the full tiles and covered the table. I would have had to shave about an inch off the length and width of the plywood, but I could have made it work. I would have also had to drill a hole in the center of the middle tile with a ceramic bit, which I do have, but it's not large enough for the umbrella pole. I had a choice of grinding the hole with a Dremel bit for 5 or 6 days (exaggerating), rent a wet tile saw, or creating a mosaic design on the table. I opted for the mosaic because it seemed like the most fun.
I smashed all of the 16" tiles and for variety I also tossed in a few smaller 12" tiles that I had leftover from my Kitchen floor. I broke the tiles into pieces smaller than 5" across, but I was looking for variety and irregular shapes more than size.
I troweled out some mortar near the center of the plywood and used a cheapo plastic notched trowel to thin out the mortar to the desired thickness. I used the 1/2" notches. I laid the tile out with an interesting pattern, trying to fit the largest pieces wherever I could. You have to work quickly because the mortar will dry out. I had to back butter the smaller pieces with mortar, which made them sit a little higher than the big pieces, but overall everything is very level and smooth.
Step 4: Grouting and Finish
I bought a medium tan sanded grout to fill in the large gaps. I washed off the excess with a big sponge, but I tried to keep as much grout as I could in the cracks to try to preserve an even surface.
Step 5: Failure and Lessons Learned
These pictures were taken after the table sat outside in the elements for the summer and fall seasons. The rain caused cracks to open up in the grout, the thinset to separate from the base and the edging tiles to fall off entirely.
My first mistake was settling on a sheet of plywood for the base. I have read that cement boards are available in 4'x8' sheets, but my local store only carried the 3'x5' sheets. I didn't want to have a seam running down the middle of the table, so I went with the plywood instead, thinking a 3/4" or thicker sheet would eliminate enough flex to prevent cracks (it didn't). I probably should have found a supply house that had the cement boards.
My second mistake was not spending more money on the thinset mortar. If I had spent a little more on a latex modified thinset, it would have been more flexible, waterproof and freeze proof. The small glass tiles that I used for edge-banding didn't stick very well. After 6 months, almost all of them have peeled off. I might have gotten them to stick better with the better thinset mortar.
For the mortar, I knew I was filling large gaps in the tiles and I wanted to make sure I had a good thick layer of grout between the tiles. I used a latex modified grout for added strength and flexibility but I did not use a liquid additive that might have given more flexibility. Unfortunately, the flexing and warping plywood caused the grout to crack.
I think this method would have worked better on a smaller table, or one that was meant to be kept in a covered area where it would be less exposed to the weather.