How to Construct Footings and Foundations for a Manufactured Home

Like custom built homes, manufactured housing needs good footings and foundations to support the weight of the structure. Having a manufactured home resting on a solid foundation will keep it from settling and shifting over time. This will help to maintain the integrity of the home and make it more livable for a longer period of time.

You need to identify the load bearing areas of the manufactured home before starting to install the footings and foundations.

Several ways exist to obtain the information regarding the placement of footings and foundations for a manufactured home. The dealership where the home was purchased should be able to furnish what you need to know. If you purchased the home used, the former owner probably knows how to place the foundation and footings. The manufacturer will have materials to guide you if none of the other options work. Of course, most manufactured homes are built to similar specification, so that you can use the information from the same size home as a place to begin if all else fails. The similarities in manufactured homes is why mobile home parks can set up sites ahead of time that almost any home can sit on.

Drive a stake at each corner of the area where the manufactured home will sit.

Stretch a cord or string around the perimeter of the site. Mark each point around the perimeter where supports will be needed. For mobile homes, a few piers down each side will handle the weight of the home. If you are dealing with a double-wide or modular home, you may need to pour footings and a foundation around the entire perimeter of the structure.

Measure from the edges and ends of the perimeter to locate the placement for interior piers.

Almost all manufactured homes need some type of support in a few inside areas of the structure. Mark these areas so that you can install the supports correctly. If the manufacturer's specifications call for some of the supports to be larger than others, make sure to identify these as you mark the locations. When all of the markings are completed, remove the stakes and string so that it will not create problems during the digging phase.

You will need more than a shovel to dig out for the footings.

For larger foundations for double-wide and modular homes, you will want to employ an excavating company to dig the trenches with a backhoe. If you only need to dig openings for piers, an auger on the back of tractor or a hand held gasoline auger should do the job. Dig the holes or trenches deep enough to be below the frost line. In the Midwest, for example, the frost line is about 30 inches deep. This means the hole or trench should be close to 36 inches deep. The width of the holes and trenches should be 12 to 14 inches.

Drive rebar into the bottom of the holes or trenches.

Sink the rebar about six inches into earth. The rod can extend to the top of the hole or trench, but it only needs to be about 18 inches out of the bottom. In a trench, the rebar rods should be spaced about two feet apart. Attach wire or rebar rods to the upright rebar so that they are connected together all of the way around the perimeter. For the holes that were drilled for piers, there is no need for additional rebar to be attached. Pour enough concrete into the trench or holes to make a footing 12 inches deep. Allow the concrete to completely fill the opening from side to side. The top of the concrete can be left unfinished.

Put wire to reinforce the concrete into the trenches and holes.

Leave the wire down from the top of the trenches or holes two or three inches. To conserve concrete, you may build forms in the trenches to limit the foundation width to 8 inches if you want to conserve concrete. If not, fill the entire hole or trench with concrete. When all of the concrete has been poured, use a trowel to put a level finish on the concrete.

Use concrete blocks to build up the foundation and piers to the desired height to support the manufactured home.

If you prefer a cleaner look, you can build forms on top of the foundation to construct concrete walls for the manufactured home to sit directly on top of. Once the manufactured home is sitting in place, use appropriate anchors to secure it firmly to the ground.