This project explains how a sagging front porch foundation is repaired by raising with helical piers.
Porch Foundation Failure Signs
The right side of my front porch was sinking over time and growing worse. The gutter installers commented the porch roof was unusually sloped by a couple of inches as they pitched the gutters. Compare the 2nd story window frame with the noticeable tilt of the sidewalk and flagstone porch:
Several years ago the porch developed a crack the entire width of the porch. More recently the crack had opened up to 1 inch wide in places indicating the problem was worsening. The crack is a clear indication the porch foundation is settling:
The right end of the porch has sunk about 2-1/4 inches at the sidewalk and step:
Swaying Porch Post
I placed my hand against the corner post as I leaned in for a closer inspection. To my surprise the porch post swayed! The porch foundation has sunk so much the post is floating – hanging from the roof and carrying no load. The weight of the roof is carried only by the center post:
Front Door Out of Alignment
The sinking porch foundation causes the roof to sag, pulling out and down on the front wall. The stress caused the door frame to move out of square as evidenced by the gap above the door. I originally thought the door was sagging and adjusted the hinges. That worked for a while but later it began hitting the right jamb and threshold making it difficult to close. I thought above replacing the entire door – frame, sidelights and transom but realized that wouldn’t fix the problem until the foundation is repaired to relieve the stress:
Sagging Porch Foundation Repair with Helical Piers
The following diagrams explain the sagging porch foundation problem and repair. Soil subsidence due to insufficient backfill compaction caused the right end of the porch foundation to sink. For a while the roof sagged with the foundation. Eventually the foundation sank so much the roof was supported only by the center post and the right corner post hanging in the air. The foundation must be repaired before the roof collapses:
My home was built in 2000 and the way the porch foundation broke as a section indicates the footers are reinforced with rebar, otherwise the foundation would have broken in several places.
The foundation repair is accomplished by driving three (3) helical piers deep into the ground well past the soil backfill to lift and stabilize the foundation. Each pier can support 40,000 lbs which is many times the weight of the porch. The piers are driven until the torque reaches 4500 ft-lbs which indicates good load bearing soil is reached and accounts for the different pier depths:
Three or possibly four piers are needed to:
- Evenly lift the porch without adverse tilting or canting.
- Provide distributed support to eliminate stress points that might cause a foundation failure in the future.
Hiring a Foundation Repair Contractor
I met with three foundation repair contractors to solicit advice and quotes. Each contractor was rated A+ by the Better Business Bureau. The bids ranged from:
- Contractor #1 – Low Bidder:
$1500 to install a single pier. Verbal quote only with no material or warranty specifications. I asked about installing two piers and the contractor replied “I’m trying to save you money”.
- Contractor #2 – High Bidder, no documentation:
$7800 verbal quote to install four piers which includes void filling with expanding polyurethane foam and minor masonry repair to fill cracks. No printed materials, brochures or warranty information was provided. A written quote was promised within 24 hours but I never heard from them again.
- Contractor #3: Atlas Piers of Atlanta, Inc.
Wayne Farris, President, arrived on time with a full color folder that explained in detail the foundation repair options, methods, material specifications and 50 year transferable warranty.
- He patiently answered my questions, advised against void filling with expanding foam and recommended cement grouting. I can contract with a pressure grout company or Atlas can handle that for me.
- He raised concerns about locating the sewer and water lines which ran under or next to the porch and recommended a plumber to locate the lines. The workmen would dig carefully to find the lines.
- Three or four piers were recommended, probably three but a fourth may be needed depending on the foundation strength; the work crew will decide based on actual conditions.
- An itemized proposal in the amount of $4050 was e-mailed the next day. The proposal also listed the upside contingency costs of installing a 4th pier and/or price per foot of material in excess of 20 feet depth. No one knows how deep the piers must be driven to reach load bearing soil or bedrock, hence the disclosure for additional cost per foot beyond 20 feet. As it were, my porch needed an extra 10 feet of pier extensions.
- The proposal included the 50 year transferable warranty terms.
I signed the proposal, paid the deposit and Atlas Piers was on-site within a week (scheduling may vary).
Foundation Repair Cost
The total cost for repairing the porch foundation was $6,797:
- $150 for a plumber to locate the sewer line.
- $4,325 for raising with helical piers.
- $2,322 for cement pressure grouting to stabilize the soil and fill the voids under the foundation and porch concrete slab.
Remember the contractors can only provide a base cost estimate because soil conditions cannot be known in advance (unless you want to pay for extensive boring and testing). The soil could be sandy, loose or the home builder might have back filled with trash or tree debris when the lot was cleared, so it’s best to budget for the high range. I was fortunate to have good soil and the estimates I received were within 10% of the final charge.
Earth Contact Products, LLC – Helical Foundation Piers
Atlas Piers of Atlanta uses Earth Contact Products (ECP) foundation piers and provides material specifications with their proposal so you know what you’re getting. The ECP helical foundation products used on my project are:
ECP piers are hot-dipped galvanized to resist corrosion and rust:
ECP foundation underpinning brackets with the Tee-Tubes:
The steel plate on the Tee-Tube is 1-1/2 inches thick because a 25 ton hydraulic ram will sit on top of it:
The Atlas Piers truck is well stocked with foundation piers and equipment:
This project is continued in Porch Foundation Repair – Helical Pier Installation.
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