|A rare sight: our first stacked stone landscape bed in the greater Houston, Texas suburbs. I'm hoping that it will stand the test of time, and this post will describe the construction steps that we attempted in order to make it so.|
|The bane of our collective upper Texas coast existence: interior damage to a home as possible evidence of foundation settling and/or breakage. |
Screengrabbed from Houston realtor Bill Edge's article on how to care for your home's slab foundation.
Here in greater Houston, most areas are underlain by clay-rich soils that shrink and swell with changes in moisture level. They're constantly on the move to some degree, and this can wreak havoc with all manner of structural improvements.
|I'm citing greater Houston because we live here, but unstable soils are also found in many other areas of the country. This diagram illustrates the principles of foundation reinforcement. |
Screengrabbed from the website of Buildet Foundation Repair of St. Louis Missouri.
|You don't have to go far before you see an example of the rigid-structure damage I'm talking about. Here's a low landscaping wall split because of shifting soils (or so it appears). The location? Galveston County Courthouse Annex on Calder Road.|
|...and the way they replace it is by bringing in dump trucks of fill, which is often a sandy material. This then gets bulldozed around the lot for proper grading and leveling. You'll see this distinctive orange color in some photos that follow.|
|As I mentioned in this previous post, this was simply a mulch bed set on grade. It followed the contours of the lot, which is strongly sloped between these two houses to promote efficient rainwater drainage. For this reason, the bed had the visual appearance of "sagging" to the left, into the drainage swale. |
Again, nothing terrible about this, but it's very ordinary. Not much sophistication to the construction or the design. It began its esthetic life as a bunch of mulch simply tossed on top of the builder's graded suburban lot.
|OK, now we're beginning to excavate for the stacked stone foundational support. Here you see that same orange-colored sandy fill material that the builder had laid down when the house was built.|
|Support is key. Here you see the limestone aggregate and crushed granite that underpinned this stacked stone. That pile in the background is fill excavated from the footprint of the stone foundation.|
|After the outline of the bed was excavated, the area was infilled with the limestone and compacted.|
Number (4) above is what I meant when I said I decided not to fight nature. I expect soils in this area to shrink and swell and shift as the years pass, because that's what they do around here. Instead of trying to oppose this, I decided just to create a robust base, but then if the soils shift in two or five or ten years, I'll simply disassemble this wall, re-level the base, and re-stack.
To say the same thing another way, my principal investment is in the stones themselves. If I were to mortar them together and then this whole apparatus shifts much like the Courthouse Annex's low brick wall did, I'm going to damage the stones, perhaps irreparably, taking them back apart. If instead I leave this whole thing float, I'm preserving the bulk of my investment even if it requires future adjustment.
My husband took this line of reasoning even one step further in noting with amusement that, if housing resale prices in Centerpointe soften to the point where we cannot get our stacked stone investment back upon selling this house at some future point, we could simply pay movers to pick up all this stone and take it to our next house, so we could re-stack it there.
Now, on with the final bits of the description.
|The actual placement of the stones is an art. This is natural stone, so it's not all the same thickness or shape. It's basically a process of iteration to find the optimal configuration.|
|BEFORE and AFTER: "Builder basic" becomes bodacious.|
In summary, the keys to this dry-stacking approach are as follows:
- The stone is wide enough and heavy enough to bear the weight of the soil in the bed behind it without needing to be physically fixed. Narrower stone would not work without structural reinforcement.
- The wall is low enough so that significant shear stress does not occur.
- The base is robust enough (hopefully) to minimize the effects of shifting.
- The stones are overlapped for optimal weight distribution.
- The stacked stone is plumb and level so that there are no lateral forcings that would exacerbate a shrink-swell-driven tendency for the entire unit to gravity-creep. Remember what I said three or four times when describing how we built our cinder block cactus garden: whatever it is, build it level. If you fail to do this, you can expect misery, and sooner rather than later.
OK, so I know you're wondering: What the heck did this latest suburban tract home escapade of ours cost?!
Here's what went into the bill from Greenscapes Lawn and Landscape:
- One pallet of this very expensive stacked Oklahoma sandstone
- About a yard each of crushed granite and crushed limestone
- Transportation of all materials
- Labor (one day of work for the landscape supervisor and two apprentices)
|For those of you who are regular blog readers:|
YES, I tried to find an honest construction contractor who is operating above the law, including where tax payments are concerned. Note the date on that invoice stub - April 29, 2013. I signed that contract and paid this bill almost a month before I raised those potentially uncomfortable questions about the source of labor for the building of League City's new Public Safety Building. I do actually try to put my money where my mouth is - in this case, literally.
Greenscapes Lawn and Landscape is owned by a young man named Joe Cunningham. He's from another part of America where construction business doesn't exactly take place like it does in Texas. He told me that he's paying his taxes and I was inclined to believe him.
Could you get a stacked stone bed built around here for less than that amount shown above? Almost certainly. Could it be done for much less but still with equivalent construction care by an experienced professional who is actually declaring their income? Please drop me an email if you find such a contractor.
Anyway, now you know the secret as to why my husband and I are such consummate DIYers: if we limit ourselves to using legitimate contractors, we can't afford to do very much contracting. Of the massive amount of customization work we've done on our house over the past three years, this was the very first time that we hired someone.
In Part 2 of this post, I'll describe our second stacked stone bed, the supportive base for which my husband and I designed and executed ourselves, and which is different from the method shown above. Stay tuned.