What is a Sister Foundation?

There are times when a foundation wall is starting to weaken and fail. In these instances, it may need support from what is known as a sister wall, or a sister foundation.

This is a type of foundation repair that involves installing a sister wall next to the existing foundation. This allows the homeowner to keep the original foundation wall instead of replacing it, while the weight of the foundation is transferred to the sister wall. This is especially helpful for historic or old homes, which often have brick foundations or rock foundations. Getting a sister wall foundation installed requires a high level of skill and involves an inspection and formal engineering design before any repairs are made.

Benefits of aSister Foundation

There are several important reasons why for many homeowners in Los Angeles sister foundations are preferred instead of more traditional foundational wall repair. The biggest reason is that this method is far more cost-effective and efficient. Building a sister foundation instead of repairing an old, crumbling foundation is not just less pricey, it’s also an effective, faster way to create support for the existing foundation.

Even better, this method is also less invasive. It doesn’t affect the exterior of your home, which is great news for anyone with a historic home, because the sister foundation remains hidden. And if you do have an older home, it was likely built on a stone or brick foundation. By installing a sister foundation, you can keep the older elements of your house intact while still repairing issues with stability. It is also important to mention that unreinforced foundations (river rock, brick, etc.) cannot be seismically retrofitted. In many circumstances when a homeowner is looking to retain earthquake insurance, their carrier will need verification that the home meets todays’ current seismic building codes. The only way to do this with the aforementioned foundation types is with a “sister foundation”.

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Process for Sister Foundation Construction

At the beginning of the process, a trench is dug right next to the older foundation wall. This trench is where the new sister wall foundation will go. This is followed by creating pockets that will connect the two foundations.

After this, the foundation bolts are installed, usually with steel reinforcements added for more support. After the supports are in place and the wooden wall forms, concrete is pumped into the trench. It will take two to three days to set. Once that is done, the wooden forms are removed and the area is cleaned.

Timeline for Sister Foundation Construction

The time it takes to install a sister foundation depends on the size of your house and any inclement weather that may be affecting the ground. Generally speaking, in ideal conditions, it can take up to a week for repairs to be completed after an inspection has taken place.

Your Consultation with Alpha Structural for a Sister Foundation

After being in business for over 25 years, the team at Alpha Structural has over 850 years of combined technical experience. Our in-house technicians, inspectors, and engineers stand out as some of the most experienced in Los Angeles, the surrounding areas, and all of Southern California. If you are interested in creating structural support in your home with a Sister Foundation Los Angeles residents should call or email today to set up a consultation.

Sister Foundation FAQ

Does my house need a Sister Foundation?

Any kind of repairs will first need to be approved after an inspection. However, there are signs your current foundation is not strong enough on its own. These signs include sloping floors, trouble opening or closing doors and windows; signs that your house may be tilting in a certain direction.

How much does a Sister Foundation cost?

Because the ground differences vary greatly in L.A. and the surrounding areas, prices will change to reflect this. In addition, the size of the foundation, the type of foundation, and the cause of the foundation issues also affect how much the total cost is. If you would like to know more about Sister Foundation, email or call Alpha Structural and set up your appointment to have your house inspected.

Request Inspection Or Estimate

A foundation is more than just the bottom floor of your property. It is the base that supports everything you work so hard to protect. At Alpha Structural, Inc., we treat each project with that level of responsibility and respect. That’s why families and businesses across Los Angeles choose us to protect the structures that protect them. If you want your foundation built to the Alpha Standard, contact us today to schedule an inspection.

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