How ‘Bout I Break Your House? Is That Enough Compaction?
That? That’s our work. I’m not particularly proud of it, as you can probably imagine. If you’ve been in the industry for any length of time, building patios, you know that if there’s going to be failure, one of the first places that’s going to happen is right there, where the patio meets the foundation. And if you’re an installer worth your salt? You know what to do to prevent that from happening and give an installation that lasts and lasts.
But hold that thought.
This isn’t what you think it is. This isn’t a cautionary tale with the moral being “Make sure you use the right compaction equipment (type and size/power) when building a patio, dumdum.”
Because we did.
You may be asking yourself “What’s all that dirt and junk on the patio?” in the picture above. Well, my fellow hardscapers, that’s the detritus left behind from repair work.
Foundation repair work.
That’s right. We. Broke. Their. House.
You see, we know that the only way to compact clay soils is to use a rammer. And oh, we rammered. And we plate vibratored too, for good measure. We knew that there was some history of misbehaving soils at this residence, so we wanted to make sure the those under the patio were beaten into line.
We compacted the soils so hard, soils that despite the house having been built 15 years ago were still more pliable than we liked, that we broke their house. Two large cracks were found in the foundation, behind the drywall of the finished basement, and the wall itself was bowed inward in excess of an inch, with the “peak” of the bow falling dead center of the patio just on the other side of that concrete wall. So what you see above is one of two 36″ diameter sonotubes filled with concrete and excavated Ihavenoidea how deep, with one or two enormous bolts attaching those concrete monoliths to the foundation to straighten it a little, but mainly to prevent further movement of the wall.
As we’ve done subsequent work for this client we’ve come to realize that their home and that part of the subdivision in general is sitting on somewhat unstable, shifting soils, and the soils likely had as much to do with the wall failure as our compaction did.
So, the real moral of the story? Pay closer attention to the subtler clues that there may be a soils issue if the client seems to have mysterious settling problems, then design a structure that can better withstand those forces. For us, that meant taking apart a portion of this project, pouring a slab for the structure to sit on, then re-building the structure.