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Re: Adding Basement to Existing House

From: m.mcgowan@insightbb.com
Category: Foundations and Basements
Remote Name: 146.18.173.74
Date: 17 Oct 2005
Time: 12:53 PM

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Question: I want to add a full basement under my existing 2 story house in Indianapolis, IN. The house is on crawl space 60 ft by 27 ft. I need an idea of costs, things to watch out for, and how to find a contractor to do the job.

Builders Websource® Answer: Costs vary widely, however, adding a basement to an existing house is a big job and may not be worth the cost depending on the value of your home in Indiana. A finished basement is likely to cost between $90-$150 per square foot or more when installed as a retrofit to your existing home. Based on your measurements, this could cost you between $150,000-$250,000 or more including design fees and permits.

Things to consider when adding a basement include drainage and related moisture control. Do you have a high water table in your area or is your lot sloped towards the house in any direction? If so, substantial civil engineering will be required to re-grade your lot while providing a full perimeter drainage and waterproofing system. Other factors include provisions for egress in the event of a fire. Furthermore, since plumbing in basements is usually below your existing sewer lines, you'll need to pump out wastewater which adds additional maintenance and complexity to your existing plumbing infrastructure.

Adding a basement after the fact is possible but much more expensive than building a new home with a basement. Home prices in Indiana are less than other parts of the country (like California) and you may find that the cost of adding the basement will be hard to recover were you to sell the home in the near to intermediate future.

As to finding a suitable contractor, check with your city building department or chamber of commerce for reliable builders who have served the area for a period of years. Check references and even the Yellow Pages. Look for a licensed General Contractor or  foundation contractor who has experience in house jacking and basement installations. You will likely need to retain the services of an architect and civil engineering company to assist in the design and related drainage details to ensure a watertight project.

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