In order to add dirt under a mobile home, it’s important to first plan your project. The dirt pad under a mobile home should be 5–6 inches (13–15 cm) higher than the surrounding ground. However, you must leave at least 12 inches (30 cm) of space between the bottom of the home’s crossbeams and the dirt below. You may have to jack your house up and repair the foundation in order to add dirt and still have a usable crawl space. Once you’ve done this, bring in caliche or similar dirt and drag it under your home using machinery and/or hand tools. Create a base pad that slopes toward the edges so water won’t pool under your home. Then, add drainage around your house for proper water control.
What is the Purpose of a Dirt Pad for a Mobile Home?
The dirt pad under a mobile home is intended to raise the level of the ground under the home so that water runs away from the home. If a home is not constructed on a proper dirt pad, water will collect under the home. This can create significant mold problems, damage your home’s foundation, and create a breeding ground for insects. A good dirt pad will protect your home from all these problems.
What Kind of Dirt is Used for a Mobile Home Pad?
Caliche is a common dirt used under mobile homes. This is because caliche contains naturally occurring minerals that cause it to harden like cement. This allows it to retain its slope, resist being washed away by rain, and prevent muddy conditions under your home. Caliche is a great choice for a dirt pad because it provides many of the benefits of concrete with significantly less cost and effort.
7 Steps for Adding Dirt Under Your Mobile Home
Adding dirt under a manufactured home to improve drainage and protect the foundation is a serious job. It’s important to take the proper precautions to do the job safely. Here’s how:
Determine the Grade
A mobile home should be built on a dirt pad that is 5–6 inches (13–15 cm) higher than the surrounding ground. Before you add dirt, find the current grade. To do this:
- Mark two stakes at 1-inch intervals, like rulers.
- Drive the first stake 6 inches into the ground 2 feet from the outer wall of your home.
- Enter your crawl space and drive the second stake 6 inches into the ground at a point under the center of your home.
- Tie a string between the two stakes.
- Use this carpenter’s level to make sure the string is level.
- measure the difference from the ground to the point where the string is tied to each stake.
Ideally, the string should be tied 5–6 inches (13–15 cm) higher on the stake that is NOT under the home. If this is the case, the ground is sloped well enough that there is a proper grade. It does not need dirt. If the ground slopes less than 5 inches (13 cm), then you need more dirt under your home.
Plan to Add Adequate Dirt
Depending on your home’s grade, you will have to add more or less dirt. Refer to these rules when planning to add dirt:
- A standard single-wide mobile home has a crawl space that covers 1,620 square feet.
- 5 cubic yards of dirt will add 1 inch of height to the entire crawlspace.
- Raising the pad height by 5 inches requires 25 cubic yards of dirt.
Based on the difference in grade found in Step 1 you can calculate how much dirt you need to add. If you need to raise your pad height by 3 inches to correct the grade, you’ll need 15 cubic yards of dirt. Then, contact wholesalers to find the price per cubic yard of caliche. Dirt is typically sold by the cubic yard.
Jack the Home if Necessary
When planning to raise the pad under your mobile home, it’s important that you leave an adequate crawl space. At minimum, there must be 12 inches (30 cm) between the bottom of the crossbeams below your home and the dirt pad. This is necessary since plumbing repairs and other maintenance tasks require crawl space access. Overfilling your crawl space is dangerous and ill-advised.
- You must leave at least 12 inches of space between the bottom of your home’s crossbeams and the dirt below.
- If adding dirt will reduce the crawl space height below 12 inches, you must jack your home and improve the foundation.
- Work with a professional to jack up your home and raise the foundation.
- Jacking your home up will give you more room to add dirt and make the job easier.
Measure the distance between your crossbeams and the dirt below. Now, determine the distance once you add dirt. If the distance will be less than 12 inches once you add dirt, your home will have to be jacked and the foundation will have to be leveled and improved. If this is the case, contact a professional foundation repair company.
Choose the Proper Dirt
If possible, use caliche under your home. This dirt will form a natural cement-like barrier that resists water, improves water drainage, and won’t be washed away. If caliche isn’t available in your region, consult a professional mobile home foundation contractor. They’ll be able to advise you on the best dirt to use for your home.
- Use caliche or a similar dirt type to raise the ground under your home.
- Dirt is ordered by the cubic yard, so use the previous steps to find out how much dirt you need.
Once you’ve selected it, order the required amount of dirt from a wholesaler. Soil is typically sold by the cubic yard. It will be delivered by truck. You can direct the delivery driver to dump the dirt near your home to make the next steps easier.
Move Dirt Under Your Home
Although you can use a skid steer, tractor, or other heavy equipment to move dirt near your home, it is not simple to move dirt under an existing mobile home with machinery. You may need to use a combination of shovels, rakes, and hoes to pull the dirt under your home and spread it evenly.
- Use heavy machinery to move loads of dirt near your home.
- Rakes, shovels, and hoes can be used to move dirt into your crawl space.
- Because it is hard to move dirt into a crawl space, it’s best to prepare the site before moving the home into place.
As your work, be careful not to puncture belly wrap or break pipes under your home. Using tools recklessly can damage the plumbing lines under your home, which will cause plumbing leaks. Work carefully to move the dirt.
Create a Slope for Drainage
As you move the dirt under your home, make sure that the dirt pad is highest at the center and slopes toward the sides of your home. A slope of 1–2 inches (3–5 cm) from the center to the edge is adequate for drainage.
- Mound the dirt so that it is highest at a ridge along the center of your house.
- Slope the dirt down to the sides and ends of your house to encourage drainage.
- Compact the dirt to keep it in place.
Pack the dirt under your home so that it remains in place. Compacting the dirt is the best way to prevent washouts that can damage your home’s foundation. This is best done when the home is jacked to an adequate height for working, or by moving the home entirely.
Add a Drainage System
To protect your new dirt pad from water runoff, install a drainage system around your home. A swale or french drain system 2–5 feet from your foundation can collect water and direct it away before it reaches your home. This will protect your dirt pad and reduce moisture under your home.
- Add a swale or french drain system around your home to provide drainage.
- Consider adding a french drain before you add dirt under your home—it may eliminate the need to add dirt.
In most cases, drying out the area under a mobile home involves adding a drainage system. Speak to a local drainage contractor. You may be able to protect your home from water damage using a drainage system. This can reduce or eliminate the need for additional dirt under your home.
How Do You Add Dirt Under a Manufactured Home?
Adding dirt under an existing mobile home can be accomplished through the following steps:
- Find the grade of your home’s plot to see how much extra dirt is necessary.
- Calculate the number of cubic yards of dirt you need to add.
- Hire professionals to jack up your home and improve the foundation if necessary.
- Use a high quality, stable dirt such as caliche.
- Move the dirt under your home through a combination of machinery and hand tools.
- Slope and compact the dirt under your home so it sheds water.
- Add drainage trenches around your home to further protect your foundation from water damage.
Mobile homeowners who face water issues on improperly graded lots can correct this by adding dirt. A properly graded lot will shed water and protect your home from mold damage.