Can You Install Beach Stones Like Tile?

From time to time I come up with some harebrained ideas, and most of the time, we’re not 100% sure those ideas will work out in execution. An idea that worked: the cardboard lampshade. And failed: the cement planters. I do what I can to test and troubleshoot for the worst-case scenarios, and this here test is just one of those “let’s see if this works before we install it and destroy our front entryway” kind of projects.

Backtrack: My parents live near some lovely beaches. Au natural kind of beaches. Ungroomed,  rarely trekked, usually with lots of dead fish on shore that the dog just loves to snarf (which translates to “investigate mischievously”). Last summer, we spent a day exploring and came home with a trunkful of flawless driftwood and a big box full of assorted piece of shale (the mothership of more well-known slate). This box is the size of my torso, FYI.

It’s been a pipe dream of ours to coat the floor in our entryway with pebbles, rocks, something very natural and pulled straight from the earth, and upon bringing home the abundance of shale, we thought we had found our match. Although, I don’t know if you’ve ever handled shale. Or stomped on it. Or thrown it. What I’m getting at is… it’s great for skipping into the lake when you’re having a picnic at the beach, but out of that element, the stuff can be brittle. Downright fragile. The thicker pieces, not so fragile, but any pieces that are beginning to show the layers (which I’ve read is what distinguishes shale from slate, the visibility of layers) are considerably more likely to be chipped away by hand. Evidence:

And so, with sheer nervousness, the whole box of shale has sat planted on the ground in the garage, waiting for a day when I 1) Dare to install it in the front entryway as planned or 2) Find another awesome use for it.

Pete and I had very different guesses as to how a shale floor would hold up, roughly meaning that he thought it would, whereas I bet him a mocha that it wouldn’t. Doing a little disposable test patch seemed like the best way to find out how this project would go. Are you with me? Think of it like painting a test swatch on the wall and seeing how it looks and reacts in different lights, but instead, testing a possible flooring; it’s like our own little non-hazardous Mythbusters up in here, determining whether common sedimentary rocks can be transformed into real walkable tiles.

I chose to use a piece of thick plywood scrap for the base “floor”. The entryway in which this shale would be installed on is actually a cement slab, ungodly thick; solid, no flex, perfectly flat, it actually is probably the best-case placement for a potentially-fragile stone floor, as long as said stones were properly installed. Using more pieces of scrap wood, I cut lengths to act as short walls for this floor, just in case the mortar I was using ended up being runny.

I screwed the walls themselves into place directly into the thick plywood base, and was left with a nice, tight little frame. A little shale tiling zone that was just about large enough for me to stand with my feet side-by-side. Always prepared for a project to be really messy, I put a piece of OSB underneath to catch any extra moisture that might emerge; I didn’t feel like cleaning up a mortar mess on the basement floor, I still have mortar on a coffee mug from one of the days we tiled the bathroom shower, and that stuff will. not. chip. off. even two months later with weekly trips through the dishwasher.

I digress. Here’s the test surface:

I prepped the surface much like I prepped the HardiBacker for the bathroom subway tiles, using a notched trowel to create grooves with the light mortar.

I also preemptively buttered the back of each stone, hoping with all might that it would help to keep them locked into place despite there not being manufactured ridges for the mortar to grip to like on your store-bought tiles.

Laying the shale pieces itself was a puzzle; moving more quickly than I might have if I were doing the real floor, I found pieces that fit together well enough and mushed them into the mortar tightly.

I can honestly say that I wasn’t sure what I would find the next morning, after letting the stones cure in the mortar overnight. Would they tip out when I moved the tiling zone, totally loose? Would the mortar be the first to crack since the plywood board wasn’t rock-solid or cement board-based? Would the stones shatter under my weight? Under Cody’s weight? Under Pete’s weight?

Yes, it worked.

We took the dance party outside too, to bounce, stomp, be as heavy as we could make ourselves on the asphalt driveway, since the asphalt is a harder, less flexible surface for the plywood base to rest on.

Pete stomped the hardest of all, and the stones and mortar remained free of all injury. No loosening. No cracking. And we took extra joy in reminding ourselves that it wasn’t likely that anyone would ever be stomping with all of their might in the entryway, so we were probably in the clear for basic day-to-day foot traffic.

Onward with our entryway floor planning. Questions still to be answered: mortar color? Grout color? Shall we go darker than what we used here so that the inevitable foot traffic doesn’t stain the grout over time? And more importantly, has anyone actually tried this and failed? I hope not. But tell me if you know of any horror stories. Thanks in advance.

UPDATE:

See how the stone installation went in this post.

And see how it looked once grouted in this follow-up post!