Foundation and Concrete Repairs
Expert Foundation Repair Contractor Serving the Greater Toronto Area
Spotting a crack in a foundation would be enough to disturb any home owner’s peace of mind. Bulging basement walls and obvious foundation settling problems, such as uneven floors, can lead to downright panic!
Don’t despair. AFB has access to the latest foundation repair techniques and can permanently repair any settlement-related problem. Whether you need the foundation or slab to be re-levelled or foundation walls to be straightened, our proven, patented products offer fast, economical, and permanent solutions.
Don’t Ignore your Foundation Problem
Ignoring common problems involving your basement foundation can significantly deteriorate your home. Much like anything else avoiding small symptoms can exponentially lead to devastating and potential life threatening instances. If you’d like to get your foundation problem fixed permanently, you’ll first need to know exactly what’s needed for your unique problem. Whether it’s leaking foundation walls, bowing foundation walls, settling concrete, floor cracks, displaced mouldings, misaligned doors — we can help fix your foundation’s problem.
At Advanced Finished Basements, our team of certified in-house foundation repair specialists are here to help. We have the training, experience, and warranted products needed to solve any of your foundation issues. We offer written, no-obligation foundation repair quotes. Contact us today if you’d like to meet with one of our experts for a home inspection or consultation.
Foundation Underpinning in the Greater Toronto Area
Foundation underpinning utilizes high-strength round steel tubes and a load transfer bracket (retrofit foundation repair bracket) to stabilize and/or lift sinking or settling foundations. The foundation bracket is secured against the existing footing and pier sections are driven hydraulically through the foundation bracket and into the soil below using the combined structural weight and any contributory soil load as resistance. Pier sections are continuously driven until a suitable load-bearing stratum is encountered. At that point, the structure either begins to lift or the target pressure/load is achieved. The weight of the structure is then transferred from the unstable soil, to the foundation brackets, through the piers, and to firm load-bearing soil or bedrock.
Foundation underpinning develops a factor of safety against pier settlement by the pier installation methods used and the sequence with which multiple piers are driven and then re-loaded. Piers are first driven individually using the maximum weight of the structure and any contributory soil load. After all of the piers are driven, the piers are re-loaded simultaneously, and the total reaction load is distributed over the multiple pier locations. Since the average load on each pier during the load transfer operation is less than the load during pier installation/driving, a factor of safety against settlement is achieved. Typical factors of safety against pier settlement range from about 1.5 to 3.0, with higher values generally achieved for structures with greater rigidity. These factors of safety conservatively ignore any additional long-term frictional component to the pier’s capacity.
Push piers are installed directly adjacent to the existing structure utilizing side-load brackets. This introduces eccentricity into the system. It incorporates an external sleeve at the top of the pier to aid in resisting the bending forces generated by this loading condition. This helps preserve the axial compressive capacity of the pier shaft. The external sleeve extends through and below the foundation bracket to essentially create a bracket that is 48 inches tall.
The moment or bending force is localized within a relatively short distance below the bracket. Although the bending force is dissipated quickly by the pier bearing against the confining soil, it is significant and cannot be ignored. The depth or length of sleeve and pier over which the bending force dissipates is a function of the soil stiffness near the surface. The depth is greater in soft clay and loose sand, and less in stiff clay and dense sand. In soft or loose soils, a small portion of the bending force may be transferred to the pier below the sleeve, thereby reducing the pier’s allowable axial compressive capacity. A modified, lower capacity system is also available with a shorter, 30-inch long sleeve for low headroom applications.
Friction Reducing Collar
The first pier section advanced into the ground includes a larger-diameter “friction reducing collar” welded to the lead end. This collar, being larger in diameter than the pier tube, effectively creates annular space around the pier as it is advanced through most clayey soils. In soft clay or clean sand and gravel, an annular space may only temporarily be created. However, the larger diameter collar causes soil disturbance or remolding to occur, which also significantly reduces frictional resistance on the outside surface of the pier during driving. The result is a driven pier that generates most of its capacity in end bearing. Over time, the soils surrounding the pier relax back into the annular space and against the pier shaft. This provides an additional frictional component to the pier’s capacity. Even though this frictional capacity may be significant, it is conservatively ignored in the determination of the pier’s factor of safety against pier settlement.