All About Turning a Crawl Space Into a Basement

Additions and Remodels
Small Projects and Repairs
By Mateos Glen Hayes November 19, 2021

If you’re strapped for space, you might be aware that there are a bunch of different ways to increase interior space in your home. You can convert an attic into a living space, knock down a wall or two, or even convert your back porch into interior space. Another idea is to transform your home’s crawl space into a full-sized basement. At first, blush converting a crawl space into a basement sounds like a great idea for a bunch of reasons.

For one it is a great way to vastly increase your home’s interior surface area, and it seems inherently straightforward. We’re just talking about taking a “short basement” and making it taller, right? Alas, there’s a bit more to it than that, but converting a crawl space into a basement can still be a viable option for a lot of homeowners provided adequate planning and precautionary measures. 

What Is a Crawl Space? 

Before diving into the nitty-gritty, it’s a good idea to talk about what we mean when we say “crawl space”. Put simply, a crawl space is an unfinished space located between the first floor and the ground of some houses. With a typical ceiling height between 3 and 4 feet, crawl spaces can only be accessed by crawling, hence the name.

A crawl space does the same things a full-size basement would do; house plumbing, HVAC systems, and the home’s foundation. They are usually built-in warmer regions where a traditional basement may be both expensive and unnecessary. Crawl spaces help with radon mitigation, protect residents from harmful gases such as carbon monoxide, and can also keep out moisture.

Crawl spaces can be pretty useful for a variety of reasons. They can help keep your home safe during a flood and make it easier to have your home inspected since the internals is in the crawl space rather than in a concrete slab foundation. However, crawl spaces do not work well in cold weather because they aren’t below the frost line and that means that pipes in a crawl space could easily freeze in sub-zero temperatures. Crawl spaces are also more difficult to inspect when compared to a full basement since you’re unlikely to go in your crawl space all that often and problems can be harder to spot.

Can You DIY Convert Your Crawl Space Into a Basement?

This isn’t a DIY Project, and you’ll need the help of some builders and contractors to complete it. Digging out a crawl space tends to be a complicated project with lots of variables and plenty of important things to consider. After all, messing around with your crawl space means messing around with your home’s foundation, so you don’t want to go into this project half-cocked as messing up could lead to structural problems for your home.

There isn’t one hard and fast answer for all homeowners when it comes to this question. In general, anyone with a crawlspace can convert it into a basement, but the real question is whether you have the money and the time to see the project through. 

How To Turn Your Crawl Space Into a Basement

The average cost of converting a crawl space into a basement is around $50 per square foot. Assuming that your basement will be around 400 square feet (considered small), this means you can expect to pay around $20,000 when all is said and done. Of course, the bigger you make your basement the more you can expect to pay. 

Digging Out A Crawl Space

This is the hardest part of the project because it requires quite a bit of logistical support. Thousands of cubic feet of soil need to be excavated, and the footings around your home have to be seated deeper and deeper to keep your crawl space foundation from sinking. The whole process is rather slow as digging too quickly could cause the home’s foundation to become unsettled. Concrete is poured into the growing basement at regular intervals to prop up the crawl space foundation.

Where To Start?

Where To Start?

Floor and Drainage

New foundation walls also have to be poured in with concrete as the footings are extended. By the time the basement is fully dug out, it will be walled in with concrete allowing a floor to be poured in as well. Drainage must also be installed so your new basement stays nice and dry. By this point, your basement is ready for some final touches. 

Take The First Steps In Your Renovation Process

Take The First Steps In Your Renovation Process

Finishing The Basement 

You now have the makings of new interior space in your house, but there are still some final touches to do. A basement contractor can help with finishing the basement, ergo installing lighting, steps, power outlets, framing, insulation, drywall, subflooring, flooring, and HVAC vents. All of these additions will make your dug-out space into a new room in your house. Without these creature comforts your basement will be limited to storage.

Of course, that isn’t a problem if storage space is your main priority. You can forgo the finishing additions such as drywall, flooring, and insulation. Sticking with the basics will give you a basic storage space without any amenities which is more than enough for storing most items.

Add The Finishing Touches

Add The Finishing Touches

Other Crawl Space Basement Ideas 

If you opt to not expand your crawl space into a basement, there are still plenty of ways you can improve your crawl space and make it more usable.   

Storage

Even a small crawl space can be used for storage. For example, rarely used items such as Christmas or Halloween decorations can be stored in the crawl space if you’re trying to declutter your home. If your drawers are overflowing with winter clothing you rarely or never use, those clothes can also be stored in a crawl space. Rarely used tools, craft supplies, and appliances can also go in your crawl space so they’re out of the way.

Even food can go down in your crawl space provided it isn’t sensitive to moisture or changing temperatures. For example, dry and canned goods should be just fine in a crawl space. Having said this, it is highly recommended that anything you store in a crawl space is placed in thick airtight boxes first to keep out dirt and pests. You should also take the time to inspect your crawl space before putting anything in it. Excessive moisture or heat should both be mitigated before you stick anything down there. A crawl space cleaning is also a good idea to keep your storage area free of dust.

What Else Can You Do?

What Else Can You Do?

Revamp Your Moisture Protection

In a crawl space moisture emanates from the soil floor and this can increase humidity. If humidity becomes too high, your crawl space could become a hotspot for mold and pests, so it’s important to regularly check for moisture and to mitigate where possible. A crawl space vapor barrier is the best way to contain moisture and prevent these problems from developing.

The thickest crawl space vapor barriers are the best choice because they tend to be more durable and are usually better at containing moisture. They’re also better suited for withstanding regular foot traffic. When installing the vapor barriers, ensure that liners overlap and that seams are taped up so that the liner forms a perfect seal.

Don't Forget To Protect The Crawl Space From Moisture

Don't Forget To Protect The Crawl Space From Moisture

Crawl Space Insulation Upgrades

Frost is always a concern with crawl spaces, especially if you live somewhere that gets seasonally cold. If your water pipes run through the crawl space they can freeze if the weather gets too chilly. Fortunately, you can reduce the likelihood of this happening by installing crawl space insulation against foundation walls. Rigid foam insulation is the best for your crawl space walls since it isn’t vulnerable to water damage and can easily be installed using mechanical fasteners. Just be sure to install thermal insulation under your crawl space vapor barrier.

Insulation Protects From Frosty Weather

Insulation Protects From Frosty Weather

Written by
Mateos Glen Hayes

Written by Mateos Glen Hayes