What is Mobile Home Underpinning?

Mary McMahon
Mary McMahon

Mobile home underpinning is the foundation of a mobile home, providing support when the home is set up in a stationary position. It is usually subject to a regional building code for safety and it is important to make sure it is installed in a way congruent with the building code to avoid fines and other issues. A number of companies manufacture prefabricated mobile home underpinning supplies, and it is also possible to work with a contractor on site.

A strong mobile home underpinning can help keep out rats and other pests.
A strong mobile home underpinning can help keep out rats and other pests.

Installation of mobile home underpinning starts with grading the home site to make it even and level. A concrete footer is poured, and topped with several courses of cinderblocks. The mobile home can be positioned on top of this underpinning. It is common for a decorative skirting to be attached around the outside of the mobile home to conceal the underside. This may also be required by the building code if there are concerns about animals and children crawling under the home and being injured.

Underpinning serves as a foundation to support the weight of a mobile home.
Underpinning serves as a foundation to support the weight of a mobile home.

Construction of mobile home underpinning does not require extensive contracting skills, but people do need to be familiar with the process of setting up perimeter foundations, and they need to be aware of any special restrictions or clauses in the building code. A government office can provide access to the code, and often a code advisor is available to answer questions. People can also ask a licensed contractor for advice about building to code and obtaining the appropriate permits.

Once positioned on a mobile home underpinning, a home can also be attached with tiedowns to fix it in place. It should remain stable, barring extreme weather conditions, and people can add attachments like decks and other features if desired. It is advisable to periodically inspect the underpinning, just like any other foundation, for signs of crumbling, rot, water intrusion, and pests such as rats and mice. In regions where it freezes in the winter, it is important to check after the spring thaw for signs of frost damage.

In some regions, other types of foundations than the basic perimeter described here may be legal for mobile homes. People can consult the building code for more information and consider their specific needs to decide on the best mobile home underpinning. Safety is the primary concern with building regulations, as government agencies concerned with housing want to avoid situations where injuries, damages, or deaths occur as a result of unsafe living conditions or poor construction.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


I don't know whether mobile home brick skirting is any better in terms of making the house more stable, but I think the brick does a lot to improve the look of mobile homes. Sometimes the newer mobile homes are difficult to recognize from stick built houses when they have the brick foundations around the bottom.


Solid underpinning and vinyl skirting for mobile homes make a mobile home or trailer, as we always called them, look more like a house, and more like a permanent fixture instead of something that can easily be hooked up to a truck and pulled away.

You can really see the difference when you go to a mobile home park and see a mobile home with underpinning and skirting beside one without the solid underpinning and skirting. I think all of these homes should be sold with skirting and owners should be required to keep it up. Otherwise, these mobile homes bring down the value of the homes around them.


The problem with underpinning for a mobile home is that it does little to make the unit sturdier or safer. I have heard many people say they wanted a mobile home underpinned so it could stand up to storms better. The truth is that if you get a strong wind gust then underpinning or mobile home skirting isn't going to be able to protect your home.

I have known some people to add new rooms to their mobile homes, and when these additions are built from the ground up they can add more stability to a mobile home, especially when the new additions surround the original mobile home.

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