Building foundation underpinning reinforces a building’s existing foundation when that base is not strong enough to support the current structure. While traditional foundation system settling occurs to a limited degree after new construction, delayed or continued foundation settlement can occur due to several conditions. Underpinning may be required when:
- The foundation is inadequate for the soil or applied load conditions.
- The soil has changed or has become influenced by various factors.
- Adjacent building construction including site dewatering and heavy impact/vibration.
- Natural disasters have caused movement or instability in the structure.
- The building’s use has changed, such as after a renovation, alteration or addition.
- Soils adjacent and/or below the original foundations have become disturbed by new construction due to a building addition.
- The building’s structure will change, such as adding another story, which requires greater capability from the existing foundation.
- There’s been an excavation of the soil supporting the existing foundation.
- Poor site drainage or fluctuating ground water influences.
- Building foundations are placed upon inconsistent sub-strata, such as ledge, bedrock, soft soils, or poorly compacted sub-base.
- Decay of sub-soil organics or compressible soil layers.
The underpinning process can involve reinforcing the existing structure, strengthening the soil or extending the foundation to distribute the building’s weight over a greater surface area or depth. Three common underpinning processes include:
- Building Foundation Grout Injection: The grout injection method injects grout or structural foam into the ground to fill up the void under the foundation and slab, thereby improving the bearing capacity and resolving further degradation. As the grout expands, it compresses the soil matrix.
- Screw Pile: The screw pile method uses helical piles or piers and often steel-reinforced concrete grade beams to stabilize the foundations and prevent further settling. The piers have driven the nest within a suitable soil sub-stratum, where the bearing and often frictional resistance resolves the applied loading.
- Underpinning: Steel reinforced, cast concrete wall, footing, buttress and counterfort systems can be added to current concrete foundations to stabilize, support, and strengthen these systems without replacement of the entire failed foundation. Oftentimes, a sequenced and phased approach with segments of the new foundation is placed and structurally connected together.
Vital Structures LLC has a thorough process to assess your structure. Our specialty foundation engineers will evaluate your building to determine the cause of your foundation problems. Our investigation involves destructive testing, material testing and geotechnical engineering or ground penetrating radar sub-consultants, many of which our competitors do not offer. We’ll work with you to prepare and plan your structure foundation underpinning project, supporting your project from evaluation through construction administration. We will monitor the project at every step to make sure it proceeds smoothly.
Contact Vital Structures LLC About Foundation Underpinning in New England
Vital Structures LLC takes a conscientious and unique approach with each foundation underpinning project. You can count on our years of structural engineering experience. Request a site meeting today by calling 508-279-0655 or contacting us online.