A footing that has settled on soft or eroded soil can be carried past that soil on helical piers. Our underpinning design answers the practical questions: how many piers, where they go along the footing, what shaft and helix the installer uses, the bracket that connects each pier to the existing concrete, and the minimum depth and installation torque each pier must reach.
We do not sell piers or install them. The design names the shaft, helix and bracket the layout is based on and the capacity each pier must reach, which lets a homeowner compare contractor bids on equal terms and lets a contractor show the building department an engineered layout rather than a catalog page. On the day of installation we can be on site to read the torque gauge, watch the bracket seat and confirm the lift.
Underpinning an existing footing
- Existing foundation wall.
- Existing footing, left in place.
- Underpinning bracket seated beneath the footing. The load path is eccentric, so the bracket, the pier shaft and the existing concrete are all checked.
- Pier shaft installed alongside the footing, from a small excavation at the wall.
- Helix plates bearing in competent soil. Plate sizes and minimum depth come from the design; installation torque is recorded for each pier and checked against the minimum.
Scope of services
- Inspection of the settlement: crack mapping, floor elevations and probing of the footing
- Pier count and spacing from the wall, roof and floor loads reaching that footing
- Underpinning bracket selection and fit against the footing thickness and stem wall
- Minimum installation torque for each pier, from the system's torque correlation factor with a factor of safety, and a minimum depth from the soil profile
- Lift versus stabilize decision, with limits on how far a wall can be raised
- Slab, porch and chimney piers folded into the same layout where needed
- Site observation of installation and review of the installer's torque logs
- Completion letter for the building inspector, lender, insurer or buyer
How we approach it
Underpinning capacity is limited by the weakest link, and that is often the bracket or the old footing it bears on rather than the soil, so the footing thickness, concrete condition and stem wall are checked before the pier size is chosen. The layout is drawn on a foundation plan with a pier schedule, bracket detail and acceptance torque. After installation the torque logs are compared with the schedule and the completion letter states what was built.