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Written by K.H. Koehler

How to use basement underpinning for a solid (and roomier) home.

If your home is in a busy city, you might know how hard it is to find extra room for your personal or recreational interests. Stringent zoning laws coupled with tiny lots often mean you can’t build up or out. But you may be able to look down. Basement underpinning is one way to use engineering to your advantage.

It can also strengthen and deepen your home’s foundation, fix any stability issues, and turn what may be a cramped, dark cellar into a bright, full-height living space.

Building a Better Foundation

Normally, during underpinning, engineers use a “mass pour” method. They dig out sections under your foundation in a specific order and fill them with new, reinforced concrete. This shifts the weight of your house into deeper, stronger soil, ensuring your home stays level and safe.

It can both help a house whose foundation has settled poorly, often evidenced by cracks in the walls or an uneven floor, and create extra space. Underpinning lets you lower the floor of a currently cramped basement, giving you a whole new floor of living space without changing the outside of your house. You can then turn that “found space” into an office, a guest suite, or a family room. And in a popular housing market, adding square footage often means a nice bump in your home’s value so that the addition can be approached as an investment.

And since you are upgrading the space, you can replace old pipes or install modern waterproofing. You can even put in new drainage or a sump pump to keep everything dry. Plus, adding insulation to the walls makes a heated floor possible, turning a cold, damp basement space into a warm, more energy-efficient part of the house and making the living space not just larger but more livable.

The “Bottom” Line

Although the advantages can be significant, the project still requires structural engineers and professionals who specialize in specific types of work. Building permits should be secured before you begin, and you and your family should be prepared for a fair amount of noise and dust for a few weeks while the work is underway. However, it’s still a good way to maximize what your home can become, with the long-term payoff being a stable, roomy, and modern basement.

Underpinning is a good way to expand your living space, reinforce the core of your house, add support, and tap into the potential directly under your feet. It’s not a “small, weekend” project, but it can give your home stability and flexibility it can benefit from for years to come.

FAQ

Is basement underpinning safe in an older or historic home?

It is if you hire experts. Underpinning can actually help save an old house that has started to sink or shift over the last hundred years. However, if your home has any historical significance, you may need extra permits to alter it.

How much extra height can I actually gain?

Most people aim for ceilings about 8 to 9 feet high. But exactly how deep you can go depends on your current foundation.

Can the underpinning cause my property tax to increase?

Since you’re adding more usable living space, your home’s value will naturally go up, which could affect your taxes. It’s a good idea to check with your local city hall or tax assessment office before you begin.