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Mobile vs Modular Homes

Modular Home: Ground leveling and preparation

There are probably official underwriting guidelines from various insurance carriers and they may vary slightly from company to company.  We have also observed that some companies do not have such guidelines, relying upon MGAs or agency staff to identify dwellings correctly. It is important to identify the dwelling correctly so that it can be placed in the correct program.  These are the guidelines used by SEER Insurance Inspections, Inc.


Foundation: waiting for modular sections.

Site Built (stick built) Homes:

  • are constructed entirely at the building site.
  • conform to all state, local or regional codes where the house is located.  Local building inspectors check to make sure the structure meets requirements and that all finish work is done properly.
  • A well-built, cared for site-built home generally increases in value over time, although its location plays a key role in value.

Modulars are shipped in sections.
Modular Homes:
  • are constructed in sections at a factory.
  • Sections are transported to the building site on truck beds, then joined together by local contractors.
  • are built at the factory to conform to all state, local or regional building codes at their destinations.
  • Local building inspectors check to make sure a modular home's structure meets requirements and that all finish work is done properly.
  • are sometimes less expensive per square foot than site built houses.
  • A well-built modular home should have the same longevity as its site-built counterpart, increasing in value over time.
Mobile Homes:
  • Formerly referred to as mobile homes or trailers, but with many more style options than in the past.
  • are built in a factory.
  • conform to a Federal building code, called the HUD code, rather than to building codes at their destinations.
  • are built on a non-removable steel chassis (Steel frame under the house)
  • are transported to the building site on their own wheels.
  • Multi-part manufactured units are joined at their destination.
  • Segments are not always placed on a permanent foundation, making them more difficult to re-finance.
  • Have Tie downs (earth anchors)
  • Have A serial number
  • Building inspectors check the work done locally (electric hook up, etc.) but are not required to approve the structure.
  • generally less expensive than site built and modular homes.
  • Normally decrease in value over time (depreciate).
Mobile homes are pulled to a site by road tractor, are jacked up, the wheels or axles (or both) removed, the tongue removed, and some sort of foundation created beneath.  This foundation is normally concrete block piers with shims used for leveling.  It is anchored to the ground with screw-in ground rods and the house is attached by strap to these rods. 

Finished Modular
Local codes determine the distance apart.  Once the portions of the home are secured together (if applicable), strapped down, and utilities are connected and inspected, the outside perimeter is finished with skirting to enclose it.  Some people call this “underpinning;” we prefer to call it skirting, because underpinning has a connotation of foundation or strength, when it really is only a covering.  Sometimes the perimeter is bricked, but a doorway has to be left so that the under area can be accessed.

Finished Modular
Modular homes are trucked on a trailer or bed by road tractor, but not on their own frame.  At the site a foundation is pre-built, and the modular home or the pieces to be assembled are lifted by crane and placed on the foundation.  Lag bolts set in concrete attach the home to the foundation. 
Generally these houses can appear the same.  The same siding is used on both homes, utilities are attached in the same way, and additions, steps or porches may be as elaborate or simple as the homeowner may desire.  Mobile homes may be on a brick or block foundation.


Mobile Homes

There is much misunderstanding even in the sales force of the mobile home industry, and many times people mistakenly refer to a mobile home as a modular.  Owners will even think that they have a modular, when in fact it is a mobile home, so to correctly rate these it is important to correctly identify them. 

Mobile homes: Single wide on left, Double wide on right.
  Quick Check:  The only way to determine the difference with any certainty is by looking under the house.  If you see a steel frame, it is mobile, not modular.  To confirm, somewhere on a mobile home should be a manufacturer’s identification plate and a serial number.  And a mobile home is anchored to the ground with ground straps (or should be).

Note also that the manufactured home industry continues to evolve and change, so that the difference becomes even more blurred as time goes on. We welcome any comments or suggestions to refine this identification process.

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