I came home the other day and found a flyer from one of the local foundation repair companies hanging from my doorknob. “Knob-spam”, the kids call it. I started to throw it away but then saw the phrase “revolutionary new double pier perma-pile system.” Wow. Say that out loud three times fast.
Curious as to what that meant and frankly, falling for their marketing trick, I rang them up. Of course the person who answered the phone didn’t know but dutifully passed me on to sales.
I told “Mike” that I had gotten the flyer and was trying to visualize just what the “double pier perma-pile system” would be. I didn’t mention the word “revolutionary” because we all know that is a word that translates into “hype”. No reason to go there.
“Mike” went down the list of common methods of underpinning a concrete slab on ground foundation to level one that has settled: steel piers including helical, drilled “bell bottom” piers and push or “pressed” pile piers.
“Yes, yes, go on,” said I, eagerly awaiting the big reveal.
“What we do,” Mike said, “Is put two stacks or columns of those concrete cylinders side-by-side in the same hole for the same price as one. In other words, we give you two piers right next to each other for the price of one.”
Well, ok, that sounds reasonable. Engineers will say one of the flaws of the pressed pile method of foundation repair is that if one of the concrete cylinders cracks or breaks while being shoved into the ground by those above it, and it happens ten feet under ground, how are you going to know? How do you inspect for that possibility? The engineer who inspected my foundation said this doesn’t happen very often, but can and does in maybe five percent of slab underpinning projects. So having two piles side-by-side in the same hold would seem to cut the odds of having a faulty pier by half.