Thursday, October 14, 2010

Building Walls

My house is on a hill.  The entire property slopes away from the street, so that the front of the front yard, the part adjacent to the sidewalk, is the highest point, while the back of the backyard is the lowest point.  The slope, made of the shifting Austin soil that expands and contracts as droughts come and go, has wrecked the foundation of the house over the sixty years since it was built, but that's a whole, 'nother, expensive story.  The slope, most pronounced in the front yard and at the sides of the house, has also slowed my process of making gardens.  Every time I think, I could build a garden there, I realize that, first, I need to build a retaining wall there, or I will lose all of my soil and water to the hill.

For years I have been staring at retaining walls, noticing how others have used stacking landscape blocks to enclose a garden, create a raised bed, or hold their lawn in place.  I've read the in-store Home Depot display about terracing a slope so many times that I have it committed to memory, and I've stood in front of the pallets of concrete garden wall blocks almost as many times, calculating the price of a wall.  Last week, after I had finished digging the grass and weeds out of the future front-yard garden, I realized that it was time to build a wall.  Or three.

I fear doing things that I've never done before, partly because I'm human and we seem to like the comfort of familiarity, and partly because, as people go, I am one who could be described as uptight.  I like to feel that I am in control and like to appear that I know what I am doing, that I am competent, etc.  But I think what I fear most about a learning a new process, especially one to do with home improvement, is that I don't know where I'm going to get stuck.  I just know that, when it has to do with this house, I am going to get stuck.  I am going to find myself sitting in the dirt in the front yard with a perplexed look on my face as I realize that, before I can go another step further, I have to go back to the home-improvement store for a crucial tool.  The ads for home-improvement stores really should say, We dare you to do it in just one trip.

So this time I planned for three trips - one for each wall.  For each trip I borrowed Lee's truck (and for one trip, Lee himself) and took a pair of gloves for the heavy work of moving bags of leveling sand and garden-wall blocks, first from the display pallet to a flat cart and, later, from the cart into the bed of the pickup. On the first trip I also bought the heavy tool for tamping the soil and sand at the base of the wall.  I hoped that I had everything that I would need.

The first step of building the retaining wall was to dig the trench.  I used a tape measure on either side of the garden to place a string, held taut between two large stones, marking the straight line where I wanted to dig the trench.  The trench needed to be about a foot wide and deep enough that the first layer of blocks would be at least half buried in the soil in the front of the wall.  I imagine that digging the trench can be the longest, and most labor-intensive, step of the process, depending on how dry or compacted the soil is.  Because I had just spent many hours turning the soil in the area where I wanted to build the walls, digging the trench went fairly quickly.  Moving all that soil was still heavy work, especially when I had to move the trench somewhat to accommodate an old water-access tube.  Once the trench was dug, I used the tamping tool to compact the soil at the bottom of the trench.

Next I added leveling sand to the bottom of the trench, distributed the sand along the length of the trench, and used the tamping tool to flatten the sand.

Now I was ready to start placing wall blocks.  I measured and readjusted the "straight-line" string, so that it was straight and parallel with the sidewalk.  I started with a wall block in the middle of the trench, nearest to the old water-access tube, so that all other blocks would be in line with that one.  I made sure that block was level and tilted slightly backwards, then I added a block to the right.  I adjusted the second block until it was in line with, and level with, the first block.  I continued down the row in that way, making sure each block was parallel with the straight line and level with its neighbors.  I found it helpful to have a gardening spade and an extra bag of sand for adjusting the level of the blocks.  Luckily, the blocks on each end of the first row fit perfectly when set at an angle, creating rounded ends to my wall.

The first layer of blocks took some time and required careful attention to the details of straightness and level.  I did a lot of adjusting, checking the level, and adjusting again while I was putting the first row in place.  Once the first layer was straight and level, though, the next layers of blocks were easy to install.  I simply placed the blocks on top of the previous row so that each block was centered on the joint between two blocks of the previous layer.  The garden-wall blocks have a lip on the bottom of the back side that keeps the blocks from sliding too far forward and creates a small set-back between layers of blocks.  Quickly, one layer of blocks turned into three, and I had built a wall.

Well, I had almost built a wall.  One problem arose with the second layer of blocks.  Because every block in the second layer was offset compared to the layer beneath, I ended up with enough space for a half block at each end of the second layer.  Half blocks I hadn't considered.  I planned on using as many full blocks as would comfortably fit and calling that good enough.  I didn't need to be fancy, after all.  But I hadn't considered that offset layers create the need for half blocks.  No way around it, really.  So the first wall, with its incomplete ends, had to wait until after the next trip to the home-improvement store to be finished properly.

The crucial tool that I needed to break a block in half was a masonry chisel, which I found, after some searching and help, on the second trip to the home-improvement store, while Lee was happily stacking blocks onto the cart.  Using the chisel was loud work, banging a hammer on a metal chisel on a concrete block, and I couldn't help but wonder if my neighbors were hating me that day.  But it worked, eventually, and, luckily, I only had a few half blocks to make. 

I used the chisel to score a line down the middle of the top, the bottom, and the back of the block, and I just kept making the carved lines deeper until, all at once, the block broke in two.  Each half block completed one side of the second layer of the wall, allowing me to add the final bricks of the third layer.

With the wall now complete on both ends, I placed a strip of landscape fabric behind the wall to slow the movement of soil through the wall. 

Finally, I shoveled the soil back into the space behind the new retaining wall, holding the landscape fabric in place as I worked down the length of the wall.  Once the soil was level with the top layer of blocks, I raked the soil behind the wall to level it.  My first terrace was now complete.

Now that I had all the necessary tools, and knew how to break a block in half, the second wall went in faster than the first, giving me a second terrace for planting.

Later, I built a third and final wall, creating a third terrace for planting.  With the retaining walls built, finally it was time to amend the soil and plant a garden.

No comments:

Post a Comment