Mobile Home Foundation Requirements Listed By General Area

You’ve weighed your setup options for your new mobile home. And you’ve decided that a permanent foundation is the way to go. That’s why you’re wondering about mobile home foundation requirements. Are there any differences between areas of the United States when it comes to your mobile home foundation?

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Are you aware of what is supporting your mobile home? You might be surprised to know that there are different types of foundations for mobile homes. Each with their pros, cons, and uses. As with any building, the foundation is one of the most important parts. Without a good foundation, your home’s frame is under a lot of stress. The type and quality of the foundation can even determine whether financing will be approved. The Federal National Mfd. Housing Construction and Safety Standards Act of 1974 (HUD) has strict requirements in place to ensure the quality of a foundation for the safety of the home’s occupants. Find more information here. So without further ado, let’s find out more about the mobile home foundation types, which foundation you have and how to be sure your foundation is up to code.

What is a mobile home Foundation?

A foundation is required for mobile homes to provide the necessary stability and support for the structure, even though they are already built. There are different types of manufactured home foundations available, and the mobile home foundation is essentially what the home is built on.


Let’s kick off with the different types of mobile home foundations. We can start by dividing mobile home foundations into two primary categories:

  • Permanent foundations
  • Non-permanent foundations


As the name suggest, these foundations cannot be removed and placed somewhere else. Going with the permanent option allows the owner to affix his/her mobile home to the foundation permanently. Permanent foundations meet the requirements for your home to be seen as “real property” in most cases. This will make it much easier to apply for financing on your home, especially financing that is FHA assured. FHA financing depends on a combination of other factors, such as the type of foundation and the area.

What is considered a permanent foundation for a mobile home?

Permanent foundation construction must meet many standards, which are sometimes area-specific. They also require more materials. For these reasons, they are more costly than non-permanent foundations. If you own the piece of land or you do not plan on moving the mobile home, a permanent base may be the way to go. Although they are expensive, they have many benefits:

  • Higher chance of financing
  • Home has a higher resale value
  • Slower depreciation in value
  • Better support and protection against the elements



Mobile Home Foundation Types

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There are a lot of considerations to have before choosing this kind of foundation. For one, the measurements of the basement have to fit that of the home exactly. If it’s a little too short or long, you will need to relocate the walls. An expensive correction. You will also need to make sure that the basement’s walls and footings (where your home will sit) meet area-specific building codes. These codes depend on the soil condition, local rainfall and, energy standards.

You will also need to make sure that the basement’s walls and footings (where your home will sit) meet area-specific building codes. These codes depend on the soil condition, local rainfall and, energy standards.

A big concern with basements is how well they can keep out water in case of a flood or heavy rainfall. To combat this, you will need drainage pipes and gutters. Coarse gravel can also help keep the foundation dry. Insulated walls add further protection.


A huge advantage of basement foundations is that a proper installation should allow your home to qualify for real estate financing.


The basement is constructed much the same way as for a stick-built home, with a few special exceptions.

  1. First, the soil is removed. Disposing of this massive amount of dirt can be a headache. Unless you can move it yourself, it will be an extra expense. If you want a walk-in basement or your home is on a slope a good contractor will use the dirt to create a drainage slope.
  2. Next, the cement walls need to be poured in place. The walls must meet the exact dimensions of the mobile home. Leaving them too long or short can have serious stability and water prevention implications.
  3. Afterward, support columns need to be installed. The number of columns and their placement depends on your mobile homes support beam placement.
  4. The home now needs to go on top of the foundation. There are two ways: Use a crane, or roll the home onto the basement with a roller system.
  5. Finally, the axles, wheels, and hitches are removed before the home is attached to the floor joists and with nailing strips.
Advantages Disadvantages
Good earthquake resistance. The most expensive option.
You can easily incorporate a slope into your plans. There is always a chance your basement will get flooded.
Extra livable space. Long and complicated installation process.
Real estate classification and finance approval.  
  • If your home has a deep enough slope, turn your basement into a “walk-in.” Add a door and some windows to the exposed wall and create a space that feels just like an extension of your home.
  • You can also turn this area into a garage. The slope will have to be very deep to allow for a taller basement, and it will probably cost more.


Pit foundations share similarities with basement foundations, but they have some key differences:

  • While a pit foundation is also dug out into the soil, it is usually not large enough to form a living space like a basement. The crawl space formed with this foundation is useful for utilities and storage.
  • While they are still a relatively expensive option, they are much cheaper than basement foundations.

Because these homes start at ground-level, they are becoming more popular, as they look like a stick-built home. A proper installation will also ensure that your home qualifies as real-estate and you will have better financing options.


They have similar real estate financing opportunities and demands to basement foundations.


The construction process is also almost identical to a basement foundation. Care needs to be taken that the walls are exactly the length and width of the mobile homes measurements. There will also be support columns in the middle of the pit to support the homes beams. These can be simple concrete blocks or piers like a normal mobile home foundation. The home is also attached to the foundation in the same way as a basement.

Advantages Disadvantages
The appearance of a stick-built home. Still an expensive option.
Extra space to hook up utilities and use as storage. Susceptible to floods and hard rains.
Real estate classification and finance approval.  


Non-permanent foundations have the advantage of being able to detach from your home, meaning you can move it easily. On this type of foundation, the home’s axles, wheels, and hinges aren’t removed. Unfortunately, you won’t be able to apply for real estate financing and loans.


This foundation is a single slab of concrete poured onto the ground in the shape of the home. Because the home will rest on the slab through the use of piers, it does not need to be as precisely measured as the previous foundations. Usually, the slab is a bit larger than the home. A skirting can be used to cover the area between the home and the slab.


An uninsulated slab is not properly protected against the freezing and thawing of the soil beneath it. In this case, your home might not meet the requirements of real estate, depending on the area. Check with the authorities in your area and make sure your contractor does the necessary insulation.


A slab is the simplest type of foundation for building and installing a mobile home. Once the foundation is set, it provides the perfect working space to add the support columns and home.

  1. The earth is leveled out in the area where the slab will be.
  2. A wooden frame is made that roughly fits the perimeter of the home. The planks are countersunk and leveled to ensure a uniform slab.
  3. The cement is simply poured in to fill the slab. Some extra support in the shape of metal rods can be installed.
  4. The slab is left to dry completely.
  5. Piers or footers are placed on the slab where they can support the homes I-beams. They can be anchored to the slab.
  6. The home is lowered down onto the footers and piers and can be permanently fastened to them.

Since it is one huge, single piece of concrete, it is not suitable for a sloping lot. There should also be proper supports laid within the concrete, so it does not move and crack with the soil.  This means that you should be wary of the frost line in some areas.

Advantages Disadvantages
The cheapest, simplest and fastest foundation to install. You need to be aware of the frost line in your areas and insulate it if needed.
You will have a crawl space between the slab and home. Not suitable for sloping lots
  Because the slab can move, it may damage plumbing running through it.



Finally! A foundation name that is not self-explanatory. A runner foundation is not similar to any of the previous foundations, although it is closest to a slab foundation. Runners are made up of thin stretches of concrete that either run from side to side or has one “backbone” in the middle with perpendicular runners extending from it. The exact layout of the runners needs to match up to your homes support system so that the homes I-beams can rest on piers that sit on the runners.

This is one of the cheapest foundations, but it depends on the size of your home. Since more effort is required to precisely lay the foundations, unlike a slab, the contractor may charge you more. Regardless, it is still not a popular option. Such a long and thin concrete construction can crack, move and bend even easier than a slab foundation. In most cases, it is recommended you just go for a slab foundation if you need to choose between these two. It has the upper hand over slab foundations in cold areas though, because there isn’t a huge slab to freeze the soil underneath it. There is also less chance of a moving foundation affecting your plumbing.


Yes, if the piers or footers are anchored to the runners and the home is permanently fastened to the piers your mobile home can qualify for real-estate status. It depends on the local soil and frost conditions.

  1. Wooden planks are used to create the frame of the foundation. They are countersunk and leveled. Care is taken to follow the homes I-beams.
  2. Concrete is poured into this frame and left to dry.
  3. The piers or footers are placed on the runners.
  4. The home is lowered onto the piers or footers and fastened.
Advantages Disadvantages
Potentially the cheapest permanent foundation type. Most prone to damage of all the foundation types.
There will be a crawlspace, but the soil is exposed. Not suitable for sloping lots.
Will not interfere with your plumbing like a  slab foundation.


Mobile Home Foundation Types

Pier, or footer, foundations can come in a wide variety of shapes and materials:

  • Steel frame piers (see photo).
  • Concrete blocks that are either poured on site or precast.
  • A combination of both.

Each of these has many more variations, like pyramid concrete blocks, adjustable steel frame piers, etc.

It might seem dangerous to perch your home so high up on what look like stilts. Don’t worry, this technique has been used for ages, and there are all kinds of tricks contractors use to make sure the home is stable. In fact, footer foundations can provide excellent protection against floods, frost or moving soil.

  1. The soil is leveled, just like a slab or runner foundation.
  2. The piers or footers are put in place. The need to match up with the I-beams of your home. Each manufactured home model should specify the intervals at which piers should be placed.
  3. The piers/footers are leveled or supported by wooden wedges.
  4. The home is lowered down on the piers and fastened to them.
Advantages Disadvantages
Easy and cheap to install. Most contractors are very familiar with this kind of foundation. The piers may move separately, and your home can become unlevel. Read this article on our blog if it happened to you.
Offers flood and frost resistance, making it stand out.  
Offers easy entry underneath your home.  


The FHA maintains standards and guidelines for mobile home certification. In particular, it discusses the home’s foundation and requirements for permanently affixing a mobile home to its foundation. Make sure you follow the FHA Manufactured Home Engineer Foundation Certification to the letter. You need this certification if you want to get a loan, mortgage or refinance on your home and most lenders won’t proceed without it. You can get your home certified by contacting a professional like FC.

If you hire professionals with a good reputation when installing your foundation or permanently affixing your home, you should not have to know the code. Let’s just look at the most important aspects:

  • The foundation piers must bear upon reinforced poured concrete footings that are constructed below the frost line.
  • The tongue, axles, and wheels must be removed.
  • The home must have a skirting that covers the space between the home and foundation.
    • It should keep out vermin and water.
    • Be self-supported.
    • Have an access opening.
  • The home must have permanently installed utilities.
  • You must use a 6-mil polyethylene plastic vapor barrier if your home rests on the soil.

As you can see the type of foundation you choose for your mobile home might be one of the most important decisions you make, except for the home itself. Make sure you choose the right foundation, according to your budget, plot of land, area, and financing needs. A permanent foundation can be an expensive investment but think of the financial options you get in the long run.

Foundation footers

First, let’s talk a moment about footers. Think about this — the foundation bears the weight of the house. But what bears the weight of the foundation? That’s part of the job of the footer, which is a support structure (usually something like reinforced concrete) that goes underneath the foundation.

Because they’re wider than the foundation, footers can spread the load over a larger area of soil, helping avoid sinking or settling of the foundation. How much wider they are than the footer is something that can vary by location. For instance, in a place with certain kinds of soil, the footer may end up being even twice as wide as the foundation.

The frost line

Next up, let’s take some time to look at the frost line. And no, that’s not the title of an engrossing book, even though it may sound like it. It’s actually a term that applies to mobile home foundation requirements (and foundations in other homes, too). In fact, it may be helpful to phrase the concept we’re dealing with like this: how deep do you have to dig?

When you put a mobile home on a foundation, of course, you have to follow building codes for your area. And one code that varies based on where you’re located is how deep you have to set your footers.

When soil freezes then defrosts, it can shift. Thus, the houses set on top of this soil could also shift. Obviously, you don’t want your house shifting. Instead, you want it good and stable. Frost line requirements help prevent problems by telling you how deep you must dig to be out of the danger zone.

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Frost lines vary

The tricky thing about the frost line is that it’s not always the same even within one state. For example, in one area of the state of Utah, it could be 20 inches, and in another area 40, according to Archadeck of Salt Lake.

A line dug deep in soil

Thus, when you build your mobile home’s foundation, it’s important that you know how deep you’re required to dig in your area. If you’re feeling curious about how the frost line varies across the US, read on.

The South

There’s plenty to love about the South. Including (as any snowbird will tell you) the warmer weather. And that warmer weather translates to not having to dig as deep for your foundation as in northern states.

According to the map on which measures “extreme frost penetration (in inches) based upon state averages” you could be looking at something like 5-10 inches when it comes to frost penetration.

frost depth map of US

Courtesy of

This could include parts of states like Texas, Alabama, Mississippi, Louisiana, Georgia, South Carolina, and North Carolina, and Florida.  To determine how deep you’re required to place your footers, check your particular locality within any of these states.

The Northeast

Wondering how deep frost can go in states in the Northeastern United States? Judging again by the map, it can be above 40 inches (including a lot above 40 inches) in states like New York, New Hampshire, Vermont, Massachusetts, and Maine.

The Midwest

Looking again at the map, you can see that the Midwest has a pretty sizable range when it comes to frost line. Case in point, consider Minnesota and Missouri. According to the Star Tribune, “The Minnesota State Building Code requires footings to be a minimum of 42” deep in the southern part of the state, and a minimum of 60” deep in the northern part of the state.” Meanwhile, in Missouri, the frost line could be as low as less than 20 inches in one area.

The far West

Then take Western California. Out there, the map informs you’re going to have a much milder frost line—a low number like in the South.  

North, South, East, West— home is best

While you may be interested in the frost lines of other areas of the US, one frost line affects you directly. That is, it affects your own mobile home foundation requirements. And that’s the frost line of your own location.

Check mobile home foundation requirements in your area

Do your due diligence to determine what the requirements related to frost line are where you’re planning to place your mobile home. There can be different requirements depending on where you are in a state. So check, don’t assume. While you may be able to find the information online, you can also try calling your local government officials to check with them.

More to get you ready for your mobile home

Once you’re aware of the mobile home foundation requirements in your area, check out our article on What You Need To Know About Putting A Double Wide On A Basement. And if you’re trying to pick out your mobile home, check out our Mobile Home Buying Tip: How To Find And Buy Your Dream Mobile Home.

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