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Convert a Crawl Space to a Basement to Gain Easy Square Footage

May 20, 2015 • By Matthew Stock.

Everybody needs more space.

Although some might argue with the word “needs” as opposed to “wants,” it’s true that the quest for elbow room has been a part of our culture since the westward expansion of the 18th and 19th centuries.  Today, it’s manifested in a growing average square footage for single homes and a booming business in home additions and exterior living space.

For some homeowners, restrictions created by lot sizes, setbacks and property lines make it impractical, if not impossible, to add space to their homes.  For many, relocation is the answer but, for others, some creativity in finding new living space is the preferred solution.

One easy way to gain usable square footage in a home is to convert a crawl space to a basement, taking space fit only for limited storage and turning it into actual living space that can become a family room, hobby area or even a bedroom, depending on a family’s needs.

Converting a crawl space to a basement may seem overwhelming to some but it is a fairly straightforward job for a contractor with the skills and engineering know-how to get it done.

How to Convert a Crawl Space to a Basement

A crawl space is essentially just a short basement, typically without a finished floor.  It can occupy either a portion of the foundation (with the remainder a full-depth basement) or the entire space below the home.

It is constructed the same way as a full foundation except that the excavation will be shallower, resulting in a space that will range from 16” to four feet in depth.  Concrete footings are poured to bear the weight of the foundation and the home that sits on it and short  foundation walls are built, either of poured concrete or masonry.

Floors are usually covered with a vapor barrier and/or insulation.

To convert this low crawl space to a full-depth basement, the soil within the perimeter is first excavated to the desired depth, typically by hand.  Once the footings have been exposed, four-foot sections of the soil below them are dug out in an alternating pattern and new concrete foundation walls are poured below the footing.

Once the new foundation walls are complete, an additional knee wall is poured inside the perimeter of the foundation that overlaps the footings at the top, creating what is called a “bench ledge.”  This knee wall adds strength to the structure and serves as a retaining wall for soil outside the new foundation.

Once this is done, a full crawl space can be finished off just like an original basement – install interior drain tile to prevent future cove seepage, pour and level a layer of crushed stone and add a vapor barrier and reinforcing grid.  A new basement floor is then poured.

If the original crawlspace was a partial one, the original foundation wall can be left in place and a doorway constructed in it.  If the homeowner wishes to remove the wall, its load-bearing duty must be taken on by an appropriately sized and situated basement beam before it is demolished.

Converting a crawl space to a basement is an economical way of creating much-needed space in a home but it must be done by a qualified foundation repair contractor that uses proper engineering data and state-of-the-art construction methods.  At U.S. Waterproofing, our foundation repair experts have the knowledge, skills and engineering support to convert crawl spaces to basements efficiently, safely and cost-effectively.  Why not ask for our free advice?

Want to know more about how to convert a crawl space to a basement?  Please post your questions in the Comments box below.

Tags: convert crawl space basement, crawl space basement

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