How to Underpin a Mobile Home

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Underpinning and skirting are often seen as synonyms when referring to mobile home applications. While some underpinning can double as skirting, it is much more complex and useful than skirting. Underpinning a mobile home is a process to build a support structure under the home and is required in some areas. If you are trying to obtain financing for a new mobile home purchase and you are told the home must be on a foundation, underpinning is often to what the lender is referring.

Determining Function

Step 1

Determine if underpinning is to be structural only or if it will double as mobile home skirting. This will help you decide which materials will be used. Structural underpinning can be completed using concrete blocks. Decorative underpinning is best achieved with brick or field stone.

Step 2

Measure the perimeter of the mobile home as well as the height of the gap between the ground and the base of the mobile home. These measurements are going to be needed to determine the amount of materials you need.

Step 3

Select materials to be used. Speak to a salesperson at your local-home improvement store to ensure you are buying the proper materials. Many times, these stores will have computers that calculate the materials needed, removing all guesswork.


Step 1

Dig a thin trench for the footer. If you live in a colder climate, the footer needs to extend below the frost line.

Step 2

Fill footer with concrete. This will prevent the courses or layers of concrete blocks used to underpin mobile home from settling into the ground over time.

Step 3

Build underpinning courses using concrete blocks and vent blocks. The vent blocks are necessary to allow the mobile home to release moisture built up from heating, cooling and everyday household tasks.

Step 4

Slope the final course away from the home. This will keep water from collecting along the side of the wall, as it runs down the home.

Step 5

Install a drip cap to protect the home more from water run-off. It is necessary to take measures to prevent water from collecting near the base of underpinning in order to prevent water from pooling at the footer and causing damage over time.


If you choose to have functional underpinning, you may want to consider vinyl skirting to give your mobile home a finished look.


Do not attempt to install underpinning without a footer.

Remember to install vent blocks to prevent moisture from becoming trapped under the mobile home and causing damage.