ECP helical piers are installed under the porch foundation before raising the foundation. This project is continued from Sagging Porch Foundation Repair with Helical Piers.
Call Before You Dig – Mark the Utilities
I contracted with Atlas Piers of Atlanta, Inc. to repair the porch foundation. Atlas contacted the “Call Before You Dig” 811 service to have the electric, gas, TV and phone lines located and marked. I also hired a plumber to locate the 4 inch PVC sewer line and polyethylene plastic water line which the Call Before You Dig service doesn’t locate – at least in my area.
Looking inside the basement I knew the sewer and water lines were next to, or under the front porch. The plumber ran an inspection camera down the sewer cleanout to locate and mark it but they said it wasn’t feasible to locate the plastic polyethylene water line (.pdf page 15) over concerns it may be brittle and rupture if disturbed. We later discovered the water line ran towards the porch corner (left side of photo) along the route of the abandoned sewer line because water lines are commonly laid in the same trench as sewer lines.
Porch Foundation Repair – Helical Pier Installation
The basic steps to the lifting the porch foundation are:
- Dig small pits under the foundation where each helical pier will be installed.
- Drive the helical pier lead section in the ground at a 5 degree angle with a hydraulic motor.
- Attach and drive additional pier extensions until the torque reaches 4500 ft-lbs indicating load bearing soil is reached.
- Saw off the end of pier extension if needed to match the level of the foundation.
- Mount the foundation underpinning bracket on the pier and bolt it to the foundation.
- Pack fast drying hydraulic cement between the bracket face and foundation to make a solid load bearing surface.
- Partially fill the excavation pit with dirt and tamp.
- Fasten the lift head assembly to the bracket and set a 25 ton hydraulic ram in place.
- Connect the hydraulic hoses and raise the foundation until the desired recovery level is reached.
- Tighten the lift rod lock nuts.
- Remove the lift head and hydraulic ram.
- Fill the pit with dirt to ground level.
Drive the Helical Foundation Pier
The work crew decided three helical piers are needed to fix my sagging porch foundation. The 7 foot long lead helical section is driven in with a portable hydraulic motor. The portable unit worked best in the cramped area next to the front porch where tracked machinery wouldn’t fit:
Two 5 foot pile extensions were needed to reach a depth of about 17 feet in load bearing soil:
The ECP foundation underpinning bracket is bolted to the foundation and packed with fast drying hydraulic cement. For perspective, the top steel plate is 1-1/2 inches thick:
The pit is partially filled and compacted with a tamping tool:
Then the lift head is installed on the foundation bracket:
The crew did a great job minimizing the disturbance to the landscaping. Notice the section of pile extension pipe sawn off on the dirt pile. If the helical pile reaches the maximum torque (4500 ft-lbs) before it’s driven all the way in (meaning it’s embedded in load-bearing soil or rock), the excess will be sawn off to mount the foundation bracket:
The plumber marked the sewer line which is only only 14 inches from the porch foundation. The work crew dug carefully without damaging it:
The helical piers are driven at a 5 degree angle under the foundation. The motor rotation speed is slow with minimal vibration. They easily cleared the sewer the line:
Driving a 5 foot pier extension next to the sewer line. The porch foundation has subsided so much that corner porch post doesn’t touch the porch and is hanging from the roof:
The helical pier extension next to the sewer line:
This is the other pit dug at the corner of the porch. The foundation edges are chiseled smooth in preparation for the underpinning bracket:
Water and Sewer Lines
As the workmen continued digging (see above photo), they uncovered a 4 inch PVC sewer line and 3/4 inch plastic water line. The sewer line was already broken and located in the spot where the helical pier needed to be set. The former homeowners said the original sewer pipe was crushed during home construction and had to be replaced. That explains the abandoned sewer line entrance in the basement foundation wall. The workmen asked me to flush a toilet to make sure the line wasn’t active; I did and no water spilled out. The workmen then cut out the abandoned section of line. The pipe it clearly hadn’t been used in years having only dried dirt inside:
Here’s the 3/4 inch polyethylene water line with plenty of clearance for the helical pier. I was relieved the water line was located:
The foundation bracket is installed while working on the foundation pile next to the sewer line (right side of photo). The water line runs in the pit next to sidewalk:
Closeup of the helical foundation bracket shown in the above photo:
This project is continued in Porch Foundation Repair – Jacking with Helical Piers.
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