A basement converted from a crawl space can enhance the functionality and value of a home. But perhaps you're still in doubt as to whether it's ever possible to convert a crawl space into a basement. We've asked the experts, and here’s what they have to say.
Yes, you can convert a crawl space into a basement. However, it’s not going to be a DIY project since certain parts of the process require heavy construction equipment to accomplish. The entire project can require sufficient professional engineering knowledge and a significant amount of labor.
If you still have some additional questions about the process, don't worry. In this guide, we'll discuss the topic in greater detail. Keep reading as we tackle the detailed steps in converting your space. We’ll also discuss other important matters, such as the average costs of crawl space conversions.
How To Convert A Crawl Space Into A Basement
Take note that the tasks involved in converting basements from crawl spaces may differ for each property. But this project generally follows these steps:
1. Mark The Boundaries
Marking the boundaries of the new basement is a task that may not require professional help. As the property owner, you have complete control of the dimensions of the new subterranean space.
Here are some quick tips to help you out with this step:
- Survey the land by checking the property's official lot number in an official registry. The data should show the exact dimensions of the land to check the maximum allowable space for the new crawl space conversion.
- Once you know the measurements, mark the boundaries by burying 4- to 5-foot metal pegs. Use a metal detector to check for these underground marks in the later steps.
- You may also use above-ground pegs or stakes, but these options might become susceptible to weather damage if you're not careful.
2. Shore Up The Foundation Piers
A property with a crawl space has a pier-and-beam construction with three primary parts:
- Underground reinforced concrete footing
- Piers attached to the footing
- Stable floor joists
To shore up a pier-and-beam construction home means adding support to the foundation to prevent it from falling during the conversion process. It’s because the transformation requires digging the soil, and doing so will remove the support from the piers.
Pier drilling and pile driving are the methods used to shore up the foundation piers. These techniques prevent the piers from sagging or sinking through strategically placed mechanical jacks.
These machines carefully and slowly elevate and secure the settled foundation beam to a height that follows a recommended grade.
3. Dig The Soil Out Of The Basement
The new basement should have a depth of at least 10 feet. Take note that this step’s difficulty can largely depend on the available space to work with.
For example, removing the soil from a 20-square foot crawl space and transform it into a basement with the same surface area requires the removal of about 4,000 cubic feet of dirt. That amount of dirt can weigh about 284,000 to 624,000 pounds.
It's for that reason that heavy equipment like a dump truck should be at the scene. Moreover, backhoes and excavators are generally large pieces of construction machinery that can't fit in small crawl spaces. So finishing this step requires manual labor using shoveling dirt out of the space.
This step also allows you to save some money if you decide not to get professional help to dig out the soil. Still, you need a heavy-duty shovel for the job.
4. Pour New Concrete Into The Walls
A crawl space will usually have an existing concrete wall to help keep its shape. Make sure that the wall’s material is in a stable condition to prevent the edges of the new basement from collapsing. Moreover, adding new concrete to the wall can help maintain the house’s overall support.
5. Install A Drainage System
Keep in mind that it takes about 16 to 20 weeks to complete a typical crawl space conversion project. During that time, the underground space will most likely be susceptible to flooding from the rain. Installing a drainage system will help prevent water from gathering in the space.
One tool to not miss in setting up a basement drainage system is a sump pump. This submersible device sits at the lowest possible point of the property to hold the water drained from the nearby space.
You can read the following post to know more about how to waterproof a basement: Water Leaking Into The Basement After Heavy Rain – What To Do?
6. Add The Concrete Floor
Add a concrete floor to the space after installing the drainage system. Take note that the concrete basement floor should be level. Otherwise, it will be susceptible to certain hazards like cracking.
Pouring a new concrete floor may require you to follow these steps:
- Cover the dirt floor with sand. Make sure that the coverage is 3 inches or more.
- Install rebar and rebar chairs to reinforce the concrete.
- Mark the floor surface using your preferred marking method. A laser level usually works well for this step.
- Make and install a screed guide for an accurate level guide.
- Upon ensuring that the concrete ground is level and tight, lay the gravel bed on the ground.
- Pour another layer of sand and level it to provide an even surface for the concrete.
- Build and place forms using 2 x 4-inch boards.
- Pour the concrete onto the basement floor.
- Once dried, level the concrete by dragging a piece of wood across it.
You can also watch the video below for a visual guide on pouring a new basement concrete floor:
7. Add The Finishing Touches
Add the stairs and lighting to the new basement. Call a professional electrician if you don't know how to install lighting fixtures in the space. Also, think about adding a door to the basement's entry and exit point.
To learn more about how to finish your basement, check out this post: Do Basement Stairs Need A Door?
How Much Does It Cost To Turn A Crawl Space Into A Basement?
HomeAdvisor estimates the average cost to transform a crawl space into a basement at about $50 per square foot. Lot owners should expect to spend about $60,000 to $150,000 to finish this project for a 2,000-square foot home.
Additionally, here’s a quick breakdown of the expected costs for this home renovation project:
- Dig out a crawl space: $10,000 to $30,000
- Brace or raise a home: $2,500 to $20,000
- Crawl space excavation: $30,000 to $45,000 (for a 1,000-square foot crawl space)
- Drainage and plumbing installation: $1,000 to $5,500
- Foundation: $10,000 to $30,000
How Do You Cover A Crawl Space Floor?
Wrap a crawl space floor with plastic to prevent it from contracting water vapor damage. Make sure to check with local codes to get the suggested codes for crawlspace vapor barriers.
For example, California mandates homes in Climate Zones 14 and 16 to cover crawlspaces with a Class I or II vapor retarder.
Is Spray Foam Good For A Crawl Space?
Spray foam isn’t ideal for a crawl space because the substance can trap moisture. The excess dampness can cause moisture to become trapped in the wood. If the wooden structures are vulnerable to water damage, these materials can rot and warp.
Batt or blanket insulation is generally a better option than spray foam for a crawl space. This process seals the air before insulating the area, reducing the risks of unwanted moisture entering the area.
Can A Crawl Space Be Used For Storage?
Homeowners can use their crawl spaces for storage. However, problems like poor insulation and water hazards can surface without proper protection. Mold and mildew growth can also be an issue since the area can become fairly humid. Adding a reliable vapor barrier can help prevent these problems.
Is A Dirt Crawl Space Bad?
A dirt crawl space is a bad idea because it captures moisture from the dirt. In turn, it can lead to issues like mold growth, wood rot, and poor indoor air quality. Property owners can fix this issue with certain techniques, such as the following:
- Waterproofing the underground space
- Isolating the crawl space from the earth
- Preventing outside air leaks
While you can convert crawl space into a basement, the conversion project usually calls for a fairly significant amount of time, money, and expertise to finish.
Some of the steps include marking the boundaries, securing the foundation piers and walls, removing the soil, installing a drainage system, and adding a concrete floor. Best of luck with the project!