Digging down to deepen a basement is a popular way to create additional living and storage space and increase property values, particularly in urban areas. Common reasons for considering a basement dig-out project include:
- Shallow crawl spaces
- Uncomfortably low basement ceilings
- No yard space for expansion
- Structure cannot support building an additional story
One of the most important factors when considering a basement expansion is the condition of the foundation and the stability of the surrounding soil. Neglecting these questions can result in catastrophic foundation failure and possibly collapse of the home.
Loose Soil Must Be Stabilized Before a Basement Dig-Out
When soil is stable, conventional piles or piers are commonly used for structural support during work on concrete foundation footings and walls. Cohesive soils will often remain in place to excavated depths of 3 feet or more, and does not often need to be stabilized by grouting.
However, granular (sandy) soil is loose and unstable, resulting in soil loss during digging. This undermines neighboring structures and utilities and creates potentially dangerous conditions for your basement dig-out.
When granular soil is present, soil grouting can be performed in advance of the basement excavation to stabilize the soil and help ensure the safety and success of your dig-out project. An engineer will perform a soil analysis to determine if soil stabilization is necessary for your project.
Permeation Grouting for Basement Dig-Out Soil Stabilization
Permeation grouting is used to increase the strength and cohesion of loose soil and make it more water tight. It is done by injecting grout into the spaces between the granular soil particles, pushing out water and creating a solid mass without displacing it.
One of the important uses of permeation grouting is to support structures before the underlying soil is excavated. This technique:
- Strengthens the soil mass
- Inhibits water migration
- Inhibits soil movement during excavation
The strength can also be adjusted to accommodate manual digging or mechanical excavation.
The final result is a stronger, more stable, less permeable mass of stabilized soil that can be completed well in advance of your basement construction project. It may also eliminate the need for additional work, including shoring, dewatering or piering.
Call For An Estimate
Contact us today to schedule an appointment for one of our experienced engineers to evaluate your basement expansion project and provide a customized soil stabilization quote.