Wednesday, July 3, 2013

The Patio Project, Stage 3: Excavation

Technically, I guess Measurement should be listed as a separate stage before Excavation, but as it turned out, the measurements we took affected the digging process and, in fact, ended up turning it into a combination of digging out and building up. So I'm lumping all three stages together.

You see, our handy patio guide explains that to create a foundation for your patio, you need to excavate the entire area to a depth of 7 inches. Sounds simple enough. However, there are a couple of additional parameters: first, you want the patio to slope slightly away from the house, at a rate of about one quarter-inch of drop per foot of length, so that water will run off. And second, for the same reason, you want the surface of the patio to be slightly above, or at least no lower than, ground level. Now, if you're starting with a nice level surface, this is simple enough: you just dig slightly deeper on the far side than on the near side. But if you're attempting to build a patio that's only slightly sloped in a yard that already slopes significantly in two different directions, you can run into complications.

This picture can give you a rough idea of the problem. The four corners of the patio should be right next to the door, right below the window, and about ten feet out from each of those points. The problem is that the ground slopes down from the window to the door, and slopes even more steeply heading outward from the house. For drainage reasons, the patio couldn't be below ground level at the window, and for more obvious reasons, it couldn't be above ground level at the door. And while having the patio slope away from the house was fine, the appropriate amount of slope for its size would be about 2.5 inches—but the actual difference in ground level was more like 7 inches on the window side and more than 10 inches on the door side.

So how did we fix the problem? Well, you notice how, in the picture, the turf in the foreground looks kind of like stacked blocks, rather than a smooth slope? That's because it is.

Actually, we'd already been wondering about how we would deal with a second problem in the excavation phase of this project: where to put all the dirt we'd be digging up. And since the top layer of dirt that we removed was in the form of nice, neat rectangles of turf, Brian came up with the idea of stacking these blocks around the edges of the patio to make a wall, so that the four corners of the patio would be closer to level. In other words, instead of digging down to an even depth of 7 inches, we'd be building up the edges in the areas where the ground level was too low. We made the wall highest right at the edge of the patio, then gradually dropped off its height as it extended outward into the yard, as you can see here. So Stage 3 of the Patio Project ended up being not just excavation, but also terraforming.

This idea kind of killed three birds with one stone. It solved our slope problem, it gave us a use for the excess squares of sod, and best of all, it reduced the amount of dirt that we actually had to remove to get down to the recommended 7-inch depth. Which turned out to be a very good thing, because while removing and stacking the blocks of turf was hard work, it was a picnic compared to digging out the clay subsoil underneath. The how-to-make-a-patio guides all just gloss over this part of the process, blithely saying, "Dig the patio 7" deep," as if this were a straightforward procedure. And maybe it is for people with normal soil, but our soil is so dense that you can't just scoop it up with a shovel; you have to more or less chisel it out, chopping at the solid mass with a spade and then ramming the shovel into the pile once it's been loosened. Once again, our heavy-duty King of Spades proved indispensable for breaking up the hard-packed dirt. We also had to pause repeatedly to dig out rocks that blocked the path of the shovel—ranging from no bigger than a golf ball, so that you had to wonder how something that small could stop a metal blade dead in its tracks, to one that that was literally as big as my head. It took both of us to heft the thing over the edge of the newly dug hole.

So, with the combination of rain delays on Monday, the added work of stacking sod bricks, and the heavy-duty soil we had to bore through, it took us until around noon today just to finish this stage of the project. But we finally did get the entire hole dug out and lined with garden fabric, held down with metal staples that look like miniature cricket wickets. (Our soil is so dense that even pounding the staples in was a challenge; Brian kept hitting places where they simply refused to be driven into the ground, even by a blow from an eight-pound hammer. He finally ended up moving them around until he hit a spot soft enough to push them in.) The bit of rubble that was left over from the concrete pad we broke up last week got shoved out to the edges—particularly the far right corner, which ended up being lower than the rest of the hole even though we'd removed nothing except the outer turf. We figured the bits of concrete would add a little bulk to help build up the foundation in that area.

And there you have it: a big hole in the ground, ready to be filled with gravel and stone dust from the massive pile sitting out in our driveway. Stay tuned for the next exciting episode of The Patio Project, when you'll hear Amy say, "You load four and a half tons and what do you get...."

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