Helical Piers
The Second Coming of Christ in Foundations
This is what we need to build in tight spaces (in the forest, additions to houses, etc.) No concrete, no excavation. Just a giant screw driver and some giant screws :)
https://www.constructionprotips.com/tools-materials/helical-piers/
https://www.esogrepair.com/blog/2017/11/15/helical-pier-work/
https://www.youtube.com/watch?v=fgzNhFh-jEk
"Helical piers are basically large metal screws that are driven into the ground."
"Helical piers minimize time spent installing a foundation, causes little disturbance to the soil and transfers the weight of the structure, to soils deep into the earth that would bear the load."
"Helical piers are also fast becoming the go-to footing solution for decks, porches and additions. No matter how hard you try, the use of the heavy equipment needed to build concrete footings is going to destroy a finished yard and likely frustrate the homeowner. Helical piers don’t require any excavation, and there’s no need for concrete trucks. There are some walk-behind machines that are so small and maneuverable that they can even drive down piers inside a home."
Replication
More detail here: https://www.deckmagazine.com/design-construction/footings/helical-pile-deck-foundations_o
Helical Piers are not available off-the-shelf in the US. Instead, manufacturers train dealers/installers. However, some appear open to selling the piers and providing training to contractors. I imagine the best approach for us would be to get trained by one of the manufacturers - so we can better understand how to replicate both the piers and the installation equipment.
https://www.technometalpost.com/en-CA/professionals/contractors/
It's important to note that the equipment needs to provide data on the install - this is both how we know that we're on "solid ground" and how we meet building department requirements:
"Helical piles are screwed into the ground to below the frostline using hydraulic machinery. The load-bearing capacity of a helical pile usually relates to the amount of torque required to install it, a function of both the size of the helical plate and the soil's bearing capacity. A pressure gauge on the installation machine reads the torque as the pile is rotated into the ground. As the driver turns the pile, it simply screws into the ground until the installer is confident it's below the frostline and in soil with sufficient bearing capacity. If the soil is weak, the pressure gauge will read low numbers, which means the pile must be screwed in deeper to stronger soil. When the helix is below the frostline and the pressure gauge hits a high enough number relative to the loading requirements of the structure, the installation is complete. This pressure reading is plugged into a formula called a torque correlation that calculates the actual bearing capacity of the pile." (source)
Feedback
Dan
Houston area - Someone bought an old house in sinking Houston and the company we hired to “jack-up” the house and level installed said piers—very fast, very clean and Very stable foundation repair. I’d sure use them everywhere as they allow you to avoid costly study in poor soils and thus projects can remain on time and on budget. Do I take it you are going to manufacture them along with the machines? They need to be made like short drill stem so they can be put down in tight spaces in series, so you can insert them as deep as they need to go to hit some kind of solid base somewhere down there. The ones in Houston varied from 9ft to 15ft. before they felt like they could not move even in an earthquake! The only problem with code is how you fix the framing or foundation to them, but there are many ways to make that stronger and cheap too.