Slate Top for My Potting Bench

KBJ building me the potting bench nine years ago. A lot of the undergrowth you see in the background is Mountain Laurel.

Sorry this is blurry, but it was the only photo I could find of the bench when it was built and just stained. I would keep my barrels and some containers with soil amendments under the table.

Except for the top, the bench really held up well, especially because it was heavily used and left outside all  year.

Leftover cement board from the Newf (dog) room project. I had just enough.

We decided on a good height for me to work comfortably, then we flipped it on its side to cut and shorten each leg.

And look what we discovered on the bottom of one leg…..a carpenter bee had somehow managed to dig a hole from underneath the bottom of one of the legs. I am always amazed at how these bees can make an almost perfect circle. This was treated wood as well.

Here it is shortened and ready for prep work. My shorter containers will still fit under the bench.

Keith went around the top screwing in any area that had lifted a bit. He used stainless still screws to prevent rust.

Next, any irregularities or bubbles were taken level using a chisel.

We cut the cement board to the exact width and length of the plywood with no overhang.

Now I am screwing the board to the plywood below.

Here you can see that on the two ends there is an overhang. We used treated 1×2’s, square end up to fill in the gap underneath the two ends. You will see why later. The lag screws were in the way of just screwing them in to lay flat.

Using a forester bit, KBJ drilled so that the head of the lag screw would set inside and the board would lay flat against the side. He repeated that on the opposite end.

Now you can see why it had to be flush all the way around because we added 2 x 6 ‘s all the way around with the top being flush with the cement board. We couldn’t have done it without the filler pieces on the ends. The 2×6’s were attached with lag screws.

Now it is ready for the slate. Kbj cleared all the tools and left me to my tile saw.

Here I am ready to go. As you can see, I am in my dress clothes to do the tile work. Yeah, right. It was bloody hot (this is September!) and I was crazy uncomfortable, as I do not tolerate the heat very well. I had the slate on another work table so I could sort for two things, thickness of each tile, and a pattern for the top.

I played around with it and asked for opinions from KBJ before committing. Slate is widely variable in thickness because it is a natural stone that can flake easily.

I only had a few extras so if I broke too many I was going to be in trouble. I finally had it looking fairly decent. I wanted a slight overhang so that any rain or moisture would drip off past the wood for the most part, and also so that it would not be able to flow back under the slate and then into the old plywood top. I wanted to make this as watertight as I could. Before I removed the slate in order to glue it permanently down, I numbered each piece, but before I did that, I penciled some lines as I removed each one so that I could replace them exactly as I had them in the trial run and wouldn’t and up short on one end.

You can see that I cut narrow trim pieces of slate to go underneath the overhang. I attached the slate top and trim with adhesive made especially for exterior stone applications. I used clamps to make sure that it was firmly attached. The adhesive worked rather well, and quickly.

Unclamped it looking pretty good. In some places, when I put down the adhesive for the top, I had to use more in some places to make sure that the top would be level, allowing that the thickness of the slate varied.

I let it set up and dry overnight.

Next I brushed and brushed very fine sand into the joints.

And I brushed some more, until there were no gaps. Then comes the fun part.

Sealing the stone and bringing out the beauty of slates coloring. This shows a couple of squares after the first coat of sealer and the color is enhanced after just the first coat. I used a brush to apply it and dripped it onto the joints wetting them thoroughly. I let it dry between coats according to directions. The sealer I used is specific for stone used in exterior applications.

Now you can see the color difference after the sealer dries.

Next I did the trim stone pieces, and then began to polyurethane the wood while waiting for the stone sealer to dry.

Lastly I caulked with silicone all around the top underneath where the trim met the top and along the bottom of the trim. No water was going to get underneath that stone if I could help it. UPDATE: We have had some extended cold weather with temps in the single digits, then warm, then cold, and rain and the slate and the seams are all secure, so I am hopeful that it will continue to give me years more of service. What has been especially nice, is when I get tired, I can now easily just sit on the potting table and watch the birds.