The following are examples of common foundations for various single wides, double wides, and modular homes.
There are several types of foundations, including but not limited to…
- Crawl Space
- Cement Slab
Modular Home being set with a crane on a half basement.
Your foundation is essential to the proper balance and longevity of your mobile home. A well built foundation can prevent moisture build up, flex in the home, and sagging. Costs for a foundation have quite a range, so to ensure you’re getting the best possible price quoted from your contractor, consider using our “White Glove” package that will handle everything for you, often saving you thousands on what it would have cost if you had tried to organize the foundation and setting of your home yourself. One more thing, make sure the foundation is built to the actual dimensions (box size) of your home, not the size including the hitch!
Home supports will be placed with spacing as laid out on the foundation print – usually around 8 – 10ft apart along the length of each of the 4 beams. The exact spacing can be calculated (if the soil loading capacity is known) from the installation tables in the manuals on our website (see under Info tab) if there is not a layout supplied from the factory.
The actual supports pillars are usually built with a double stack of regular (webbed) concrete masonry blocks 8″ x 8″ x 16″ stacked with each other layer placed at 90 degrees to the last one for a better stack. If they are over 5′ high they should be mortared, otherwise they are ‘dry stacked’. On top of the block stack there will be a cap board which is a piece of rough-sawn 1″ hardwood about 8″ x 16″ upon which the steel beam of the home will sit. Once the home is placed onto the foundation the installers will drive some hardwood shims between the cap board and the frame as necessary to further level the home.
The other method is to use regular basement jack posts – they cost a bit more – about $25 each at any builder supply – and have a screw adjustment for exact height. They can be 3′, 5′ or 8′ posts.
You can generally figure about $1,500 per section to install an average home onto your foundation – either onto a concrete slab or a crawl space. Hence a Single Wide will cost around $1,500 and a Double Wide around $3,000 – $5,000 depending on the size. There will be an additional cost to install a home over a full basement, and there are usually regional differences in installation costs.A typical installation involves moving the home onto your foundation and anchoring it down. A Double wide will be bolted together, anchored to your foundation and the ridge cap installed on the roof where the two sections come together. The home installer may also include in their scope of work the installation of the siding on each end of the home, and the inside trim work to finish out the marriage wall, as well as the hook up of the utilities to the homes (water, sewer, gas line and electric hook-up). If the home installer does not include this in their bid, you will need to get additional contractors for this phase of the installation.
We can assist you to obtain contractors for every phase of this work for a small fee, or you may prefer to oversee the work yourself.
FOUNDATIONS – TYPES AND COSTS
There are generally three different foundation types – PIERS in the ground that support the home, a CRAWL SPACE (built with either blocks or poured concrete) or a full BASEMENT. The price for each of these will depend on the size of your home, and will vary from contractor to contractor.
The least expensive foundation is the piers in the ground. This is where 18 inch wide holes are dug into the ground down to the frost depth for the region (usually between 30 and 42 inches deep in the Midwest) and filled with concrete where they are level with the finished grade. The holes are usually about 8 feet apart down the length of the home, along each of the beams under the home. (There are two beams per home section). The home will be installed over the piers and supported by concrete blocks from the top of the piers to the beams. Skirting (or ‘underpinning’) will then be installed around the perimeter of the home from the bottom of the home to the ground. The price for a pier foundation system can be as little as $1,000 for a Single-wide and $2,000 for a small Double-wide.
A crawl space is the preferred foundation for most Double-wides. This is an excavated area under a home with either blocks or a poured concrete perimeter wall extending down to a footer poured at the frost depth for the region (usually between 30 to 42 inches in the Midwest). The crawl space will usually extend about 8 – 10 inches above the ground. The home is then rolled over the crawl space on a large beam and roller system, and lowered down and bolted to the foundation around the perimeter. The beams under the home will be supported in the center of the crawl space on blocks extending down to the bottom of the space. The cost for a crawl space may be as little as $6,000 for a small Double-wide, and as much as $15,000 for a large one. A poured concrete foundation will always cost more than a block foundation.
A basement can also be installed under almost any Double-wide. If a home is designed with a basement-ready frame from the factory, then it will be rolled over the basement and supported by the perimeter walls and on poles at the marriage wall. There will already be a section of the floor open for a stairwell. If the home does not have a basement ready frame it can still be installed over a basement, however your contractor will have to make provision for a stairwell, and for additional supports under the home. The easiest way to add a stairwell is to add an enclosed porch to the front or back of the home and build steps inside the porch. A basement will generally cost about $12,000 for a small home, and as much as $25,000 for a large home, with regional differences.