How to Dig Out a Crawl Space to Make a Basement

shovel and bucket digging in dirt
  • 100 hours
  • Advanced
  • 20,000-150,000
What You'll Need
Measuring tape
Spray paint or powdered chalk
Wheelbarrow or mortar mixing pan
Carpenters level
Adjustable steel supports
What You'll Need
Measuring tape
Spray paint or powdered chalk
Wheelbarrow or mortar mixing pan
Carpenters level
Adjustable steel supports

The main purpose of a crawl space under a house is to provide access to electrical and plumbing equipment and controls. Crawl spaces also help promote good air circulation, and when they're sealed, they can stop moisture and mold from seeping into living areas. Digging out a crawl space to make a finished basement is a popular project, but it's a major undertaking. Take a look at some finished crawl space ideas here before you start digging.

Benefits of Digging Out a Crawl Space

Homeowners might profit from a crawl space conversion in several ways. The first is that it significantly boosts a home's value.

This value boost is likely the most compelling benefit for homeowners debating whether a crawl space dig-out is the best financial decision. When it's time to sell your home, you'll be glad you made an investment that extends its life and boosts its resale value. Homes with basements sell 20-30% more than homes without basements and typically sell faster.

Next, a crawl space conversion is one of the best ways to add living space without building outside the house's boundaries. Crawl space conversions result in home offices, entertainment centers, multi-room living areas with bathrooms and kitchen facilities, children's play areas, and home gyms.

Many consumers don't consider the hidden expense of home upgrades until a tax assessor spoils their day. On the other hand, any significant modifications are likely to increase the value of your home.

If your home expands by hundreds of square feet, the extra property taxes might add thousands of dollars to the cost of the expansion. You may receive all of the above-ground home addition benefits without the hefty tax penalty by opting for a crawl space conversion.

As with any significant home addition, your property taxes will rise, but a crawl space conversion can add a whole new floor to your home for a fraction of the cost of an above-ground expansion.

Finally, crawl space conversions are an excellent method to add more storage space to your home. Crawl spaces are practically useless for storage, as anyone who owns one knows.

Crawl spaces are typically small and inaccessible. They can also harbor bugs and mildew and be vulnerable to water damage, putting all objects in storage in danger.

On the other hand, a basement provides ample storage space and is a much dryer environment to store your belongings.

crawlspace basement with gravel floor

Process for Converting a Crawl Space to a Basement

1. Finding a Contractor

Digging beneath your house's foundation can be a sensitive and challenging task. A competent contractor should complete this complicated operation, and most homeowners should never attempt it on their own.

2. Examining Your Foundation

A foundation examination, which must be completed before the crawl space repair can begin, should be able to detect any issues with your foundation and the rest of your home's structure.

You might be an "excellent candidate" for crawl space excavation if the initial inspection reveals nothing. However, the initial assessment may not convey the complete story or reveal faults to which you were previously unaware.

3. Building a Support Structure

The crawl space usually runs the length of the house and makes use of the foundation. In a conversion, this foundation will drop to support the basement instead, which means your home will be without a foundation in the interim.

The building crew will often create a stilt-like structure beneath the house to address this issue. It will support the entire place while the team completes the remaining phases in converting the crawl space to a basement.

However, this situation does mean that you will not be able to live in the house during this time.

4. Excavating

When converting a crawl space to a basement, a contractor must first excavate to the depth and width of a full basement. This excavation will typically be seven to ten feet deep, depending on the existing conditions and the customer's desires.

The ultimate goal is to create as much more storage or living space as feasible at a relatively low cost, but the bottom line is that this won't be cheap.

Some of the more basic tools that may be used include hydraulic jacks (if your house needs to be raised), i-beams to help support and keep the project safe, concrete for a new foundation, shovels, jackhammers, wheelbarrows for hauling out dirt, and more.

One of the biggest issues that the contractor might come across here is what kind of soil lies beneath your household.

Depending on how hard or soft the soil is, you might have different complications. If your soil is extremely hard or rocky, the contractor will likely have to bring in heftier equipment rather than what is standard.

There might also be some trouble removing this soil, particularly if it is heavy. Softer soil, on the other hand, may require more shoring up and 'maintenance' to ensure that there is no damage done to the overhead structure.

This difference in soil types is only one of the many reasons that an experienced contractor becomes invaluable, as if you're attempting to do this completely on your own, you might not know all the ways to ensure the safety of both yourself and your house.

crawlspace basement with cinder block walls

5. Laying a New Foundation

The crew will then likely need to pour a completely new concrete foundation. This concrete will serve as the new basement's floor. When they lay this concrete, they must ensure that it is strong enough to support the weight of the entire house and that it will not crack or start to slide out of position over time.

It's also worth mentioning that concrete takes a long time to cure. Depending on the type of concrete used and the preferences of the building crew, it may take several weeks for the concrete to cure completely. Construction can essentially come to a halt during this time.

6. Waterproofing

Next comes installing a waterproofing system in the basement after the concrete is poured and set for both the floor and walls of the foundation to prevent future water-related concerns such as leaks or a weakened foundation.

7. Settling

Finally, the home will next be moved upon its new foundation after the basement is finished. This entails removing the stilts and ensuring the home's weight is evenly distributed across the new foundation.

The building crew will also fill in the surrounding space, restoring the home's exterior appearance to what it was before development began.

The house will continue to settle over the next few months and may develop issues. During those few months, you must be on the watch for any foundation and basement concerns so you may contact the building crew if necessary.

Cost of Digging Out a Crawl Space

Crawl space conversion costs vary significantly from home to home, based on the size of the project and the kinds of materials involved. On average, it'll cost you about $50 per square foot, so it's likely to run into the tens of thousands, and could even be over $100,000 if you're converting a large, rocky area.

Converted Crawl Space Ideas

finished basement with furniture

Extra Bedroom

The beginning procedures for turning a crawl space into an extra bedroom are the same as turning it into a storage space. Still, a spare room necessitates that you finish the area thoroughly. Excavate to a minimum depth of ten feet.

Because you will likely be utilizing the space for recreation and sleeping, ventilation should be a top priority. You'll almost certainly need to run wiring to the area, so you may want to keep additional costs and considerations in mind.

Family Room or Home Theater

You may prefer to keep your home tidy, but you still want a place where the entire family can gather to watch TV, play video games, or rest. You may do just that by converting the crawl space into an extra room.

It's physically separated from the rest of the house and out of the way. You can even start from scratch and acoustically set up the area to provide the most refined sound while optimizing lighting effects.


Basement workshops are standard in many homes. If you enjoy working on items but lack the necessary room, a converted crawl space provides the ideal opportunity to set up a full workshop. One advantage is that you don't even need to finish the area because cinder block walls are acceptable in a workshop.

Why You Might Not Want to Convert a Crawl Space

excavation machinery

Even with the help of specialists, excavating a crawl space can be dangerous. You're essentially leaving your home on an unstable foundation for a period of time while the construction crew works on the new foundation and attempts to transfer your home's current weight. Your house could fall apart if something goes wrong.

Excavating a crawl area can also be exceptionally costly, and the procedure might be lengthy.


Crawl space conversion has become safer, easier, and more affordable over time. However, a skilled and experienced contractor is still required. This build isn't a "do-it-yourself" undertaking.

Despite the high prices and structural risk, digging out your crawl space and converting it to a basement might be worth the effort, both in terms of comfort and home value. You could even potentially create a basement apartment and rent it out for some steady income.

For more on crawl space projects, check out How to Build a Crawl Space Door or How To Seal a Crawl Space.