Below are some glossary of terms for our FHA, HUD, and VA manufactured home foundation engineering certifications and inspections. If you can not find you answer here, please also go to our Fequently Asked Questions page.

Glossary of Terms

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There are currently 133 terms in this directory

Accessory building or structure
Any awning, window awning, cabana, ramada, storage cabinet, storage building, private garage, carport, fence, stairway, ramp, or porch, or any other building or structure other than a patio, established for the use of the occupant of a manufactured (mobile) home unit.

Professional valuation done on a mobile home property to find expected value.

Reviewed and/or inspected and deemed acceptable to the local enforcement agency.

An accessory structure, used for shade or weather protection, supported by one or more posts or columns and partially supported by a unit or other accessory structure installed, erected, or used on a lot.

Awning Enclosure
An enclosure designed for outdoor recreational purposes, not for habitation, constructed under an awning or freestanding awning, which may include a screen room, and either an accessory building or structure, or a building component.

Awning, Freestanding
An accessory structure, used for shade or weather protection, supported entirely by columns or posts and, other than flashing, not attached to or supported by a manufactured (mobile) home unit or other accessory structure.

Awning, Window or Door
An accessory structure, used for shading a window or door, supported wholly by the unit or other accessory building or structure to which it is attached.


Branch Water Service Line
That portion of the water distribution system extended from the manufactured (mobile) home park water main to a lot, including connections, devices and appurtenances.

Building Components
Any subsystem, subassembly, or other system, constructed or assembled, designated for use in, or as part of, an accessory building or manufactured home structure, which may include structural, electrical, mechanical, plumbing, and fire-protection systems and other systems affecting health and safety. However, "building components" do not include appliances or equipment, such as heaters, stoves, refrigerators, or air conditioners.

Building Standard
Any rule, regulation, or other requirement adopted by the state, or a local government pertaining to the construction, plumbing, electrical, and fuel gas equipment, and installations within permanent buildings and/or manufactured (mobile) homes in parks.


A freestanding accessory building or structure, or building component of a manufactured (mobile) home unit, located immediately adjacent to and intended to increase the living area of that unit, which is a portable, demountable, or permanent room enclosure or other building erected or constructed for habitation. A cabana shall not exceed the size of the unit to which it is an accessory.

An accessory structure for vehicle parking, used for shade or weather protection, supported by one or more posts or columns and partially supported by a unit or other accessory structure installed, erected, or used on a mobile home lot.

Carport, Freestanding
An accessory structure for vehicle parking, used for shade or weather protection, supported entirely by columns or posts and, other than flashing, not attached to or supported by a mobile home unit or other accessory structure.

Certificate of Occupancy
A document issued by the enforcement agency when a mobile home unit or commercial modular, installed on a foundation system, is approved for occupancy by the enforcement agency.

A stamp of approval applied to the earthquake resistant bracing system manufacturer's plans and installation instructions.

The rectangular, usually steel frame or I-Beams, that supports the mobile home unit and to which the mobile home unit is built upon. The axles are attached to the Chassis and allows the mobile home unit to be transported.

Cited Person
A person or entity issued a notice of violation for a violation or applicable laws who is responsible for its correction.

As applied to building construction is any material or construction which does not meet the criteria of noncombustible.

Commercial Modular
"Commercial modular" means a structure transportable in one or more sections, designed and equipped for human occupancy for industrial, professional, or commercial purposes, which is required to be moved under permit, and shall include a trailer coach. "Commercial coach" has the same meaning as "commercial modular".

Common Area
An area, within the boundaries of the mobile home park, that is not specific to any lot or space and is under the ownership and control of the mobile home park.

Concrete Block Pier
An assembly of load-bearing, concrete blocks with wooden wedges used to support and level a mobile home unit.

Concrete Pier
A concrete load-bearing support that incorporates into its structure an adjustable means of raising and leveling the mobile home unit.

Someone (a person or firm) who contracts to build things and is usually licensed with the state to perform work.

Crawl Space Area
The low space beneath the floor of a mobile home; gives workers access to wiring or plumbing and foundation system.


Dead Loads (DL)
A constant load on a mobile home due to the weight of the supported structure itself.

Dependent Unit
A mobile home unit not equipped with a toilet and sewage disposal system.


Earthquake Resistant Bracing System (ERBS)
An anchoring system, bracing system, or other device designed and constructed for the purpose of protecting the health and safety of the occupants of, and reducing damage to, an mobile home unit in the event of an earthquake.

Electrical Feeder Assembly
The overhead or underchassis feeder conductors, including the equipment grounding conductor, together with the necessary fittings and equipment, designed for the purpose of delivering energy from the mobile home's lot electrical service equipment to the branch circuit distribution panelboard of the mobile home unit or accessory building or structure.

Electrical Service, Park
The conductors and equipment for delivering electrical energy from the electrical supply system or the generator of an isolated plant, to the electrical wiring system of the mobile home park.

Electrical System, Park-Secondary
That part of the electrical wiring system of the mobile home park distributing electrical energy at a nominal 120 or 120/240 volts, single phase.

Electrical Wiring System, Park
All of the electrical equipment, appurtenances and related electrical installations outside of permanent buildings, units, and accessory buildings or structures within a mobile home park.

An occurrence constituting a present or imminent serious risk to life, health, safety, or property requiring immediate correction.

The act of applying electrical energy, or gas or water pressure.

Enforcement Agency
The governy authority, or any city, county, or city and county that has assumed responsibility for the enforcement of the mobile home foundation standards.

A person registered with the State of California as a professional engineer qualified to practice engineering in this state. An engineer designing or approving plans should have skill, knowledge, and expertise in that scope of practice.

Engineer's Foundation Certification
A stamped certification by a licensed professional engineer in the state where the home resides. The Engineer's Certification states that the foundation (or permanent foundation) complies with the standards set forth by the governing agency. Also see Foundation Certification.

All materials, appliances, devices, fixtures, fittings, or accessories used in the structural, fire safety, plumbing, mechanical, and electrical systems of mobile home units, accessory buildings and structures, buildings, structures, infrastructures, and systems.

The acronym for an Earthquake Resistant Bracing System.

A person, firm or business engaged in assembly or construction of earthquake resistant bracing systems for mobile home units foundations.

ERBS-Manufacturer's Installation Instructions
The specific written directions for an earthquake resistant bracing system to be installed on or under mobile home units and foundations.

Expansive Soils
Types of soil that shrink or swell as the moisture content decreases or increases. Manufactured home foundations built on these soils may experience shifting, cracking, and breaking damage as soils shrink and subside or expand.


An acronym for Federal Emergency Management Agency.

A freestanding vertical structure erected to enclose an area or act as a barrier generally constructed of posts, boards, wood, wire stakes or rails.

FHA Loan, or Mortgage
FHA loan is a federal assistance mortgage loan in the United States insured by the Federal Housing Administration. While there are limits to the size of FHA loans, they are generous and handle moderate-priced homes almost anywhere in the country, including mobile home units.

An acronym for Federal Housing Administration. It is within the U.S. Department of Housing and Urban Development and the set the industry standards for permanent foundation systems for manufactured homes which most other agencies adhere to.

Fire Agency
A city, county, or city and county fire department, or fire district.

Fire Hydrant
A connection to a water source for the purpose of supplying water to a fire hose or other fire protection apparatus, and includes a standpipe.

Fire Hydrant System
All fire hydrants, water piping, pumps, tanks, and valves attached to the water system supplying the hydrants.

Fire Hydrant, Private
A fire hydrant including wet standpipes owned by the mobile home park.

Flashing refers to thin continuous pieces of sheet metal or other impervious material installed to prevent the passage of water into a mobile home unit from an angle or joint.

Flood Plan, FEMA Flood Plan
The lowlands adjoining the channel of a river, stream, or watercourse, or ocean, lake, or other body of standing water, which have been or may be inundated by flood water. The channel of a stream or watercourse is part of the floodplain.

Footing, or Footer
The portion of a mobile home foundation support system, in direct contact with the ground, that distributes imposed loads to the soil.

Form 433b
Owners of ${mb}s who install their unit on a foundation system are required to complete and submit Form 433B with the County Assessor upon completion of the installation. The form can be downloaded from

Form 433c
If a mobile home park is converted to a resident owned subdivision, cooperative, condominium, or nonprofit corporation and the mobile home owner applies for conversion of their home to a fixture improvement, they would use Form 433C. The form can be downloaded from

Foundation Certification
A stamped certification by a licensed professional engineer in the state where the home resides. The Engineer's Certification states that the foundation (or permanent foundation) complies with the standards set forth by the governing agency. Also see Foundation Certification.

Foundation System
An assembly of materials designed and engineered to resist the imposition of external forces once the mobile home unit or commercial modular is installed upon it. When dealing with mobile homes, it generally consists of piers and footing, a perimiter masonry block skirting on a continuous concrete footing, tie-downs or some sort of anchorage device.

Freddie Mac Lending Requirements
Below are some requirements in order to get a loan from Freddie Mac for a mobile home:
  • Built on a permanent chassis in compliance with HUD.
  • Must have a HUD certification label or data plate.
  • The dwelling unit must be legally classified as real property.
  • Must be at least 12 feet wide and have a minimum of 600 square feet.
  • Must be built after June 15, 1976.
  • Must be affixed and attached to a permanent foundation system and the land must be owned by the borrower (unless located in a condominium project)
  • Must be permanently connected to sewer or other utilities.
  • The wheels and axles must be removed.
  • Must have a licensed engineer or the local building jurisdictions approve any structural modifications.


An enclosed accessory building or structure located on a mobile home lot and designed for the storage of motorized vehicles.

Gas Connector
A flexible connector, listed for exterior use, to convey gas from a gas riser outlet to the gas supply connection of a mobile home unit.

Gas Piping System, Park
The pipe, equipment and related installations, outside of permanent buildings, units, or accessory buildings or structures, for distributing gas throughout the mobile home park.

Gas Piping, Main
A distribution line that serves as a common source of supply for more than one service line.

Gas Riser Outlet
That portion of a park gas service line or gas piping system, extending above ground, serving a mobile home lot.

Gas Service Line
The pipe or that portion of a park gas piping system, extending from the main park gas line to the individual gas riser outlet serving a mobile home lot.

Good Cause
What the enforcement agency would find to be a reasonable basis for failing to appear at the time and place scheduled for a hearing, informal conference, formal hearing, or for not complying with a specified timeline.

Grade, Existing
The surface of the earth adjacent to the mobile home before earthwork takes place.

Grade, Finish
The final surface of the earth adjacjent to the mobile home after all improvements are completed.

Gross Floor Area
The floor area enclosed within the surrounding exterior walls of a mobile home unit, accessory building or structure, or portions thereof. Where there are no walls, "gross floor area" means the usable area contained within the horizontal projection of the roof and floor.

Ground Anchor
That part of a tiedown assembly that is inserted into the ground. Note that Ground Anchors are not allowed in HUD compliant mobile home permanent foundation systems.

A vertical barrier erected along the open edges of a porch or other elevated area to prevent persons from falling to a lower level.


Habitable Room or Structure
Any structure or room within a structure for sleeping, living, cooking, or dining purposes, excluding such enclosed spaces as awning enclosures, closets, pantries, bath or toilet rooms, service rooms, connecting corridors, laundries, unfinished attics, foyers, storage spaces, unfinished cellars, utility rooms, and similar spaces.

A railing provided for grasping with the hand for support, erected along one or more edges of a stairway or ramp.

Hearing Officer
The authorized representative of the enforcement agency, or other official authorized to conduct hearings.

An acronym for the U.S. Department of Housing and Urban Development.


The main beams or girders under the mobile home having a cross section resembling the letter 'I' that supports the entire unit.

Identification Label
A decal, tag, or label indicating acceptance by the department of a standard plan for an accessory building or mobile home structure.

Independent Unit
A mobile home unit equipped with a toilet and designed to be connected to a mobile home lot sewer inlet.

Insignia or Label of Approval
A tag or label required and permanently affixed to each section of a mobile home unit indicating compliance with applicable regulations of the governing department or with the Federal Manufactured Home Construction and Safety Standards.


Landing, Stairway
An individual platform, usually at the top or bottom of a stairway, to ease the transition from a stairway to a level walking surface. Landings for ramps must comply with requirements of local codes.

Lath structure
An accessory structure of open design, having no solid roof or walls.

All equipment, materials, products, and installations included in a list published by an approved listing agency.

Live Load
A load on the mobile home that is temporary in nature and not constant like a Dead Load. For example, snow, people, etc.

Any of the forces that a structure is designed to withstand, including any permanent force such as the weight of a roof, known as a dead load; any moving or temporary force, such as the weight of occupants, known as a live load; wind loads imposed by wind activity; and seismic loads imposed by seismic activity.

Lot Access
An unobstructed way or means of approaching a roadway or public thoroughfare to or from a mobile home lot.

Lot Line Change, Adjustment
The alteration, movement, or shifting of a lot line for an existing lot.

Lot Line Creation
The initial establishment of a lot line for a new lot.


Manufactured Home (Formerly Mobilehome)
A manufactured home is a single-family house constructed entirely in a controlled factory environment, built to the federal Manufactured Home Construction and Safety Standards (better known as the HUD Code). A mobile home can be connected to utilities and can be parked in one place or affixed or place on a permanent foundations and used as permanent housing.

Marriage Line/Wall
The marriage wall is the area of our home where the two or mobile home units join together. Special mounting plates and bolts are used to ensure a seamless fit.

MH-unit, MH
A term used to replace references to "mobilehome, manufactured home, and a multifamily manufactured home".

The common term used to describe a mobile home comprised of more than one transportable section assembled together at the time of installation to form a single-dwelling unit.


An acronym for the National Fire Protection Association.

As applied to building construction is any material which meets the criteria for "noncombustible" as specified in the applicable building code.


For the purposes of this chapter, means a person who lawfully occupies a mobile home unit on a lot.

Occupied Area
The total of all the space occupied by a mobile home unit, including eave overhangs and projections; building components; and all accessory buildings or structures on a mobile home lot.

The person or entity to whom a permit to operate is issued by the enforcement agency.

The person or entity that legally owns or possesses an item, property, or business through title, lease, registration or other legal document.


For purposes of this chapter, is any manufactured housing community or mobile home park.

Park Trailer
A recreational vehicle that is considered personal property and not real property subject to taxes.

A paved or raised area not to exceed eight (8) inches in height above grade, used for access or recreational activities.

Permanent Building
Any permanent structure under the control and ownership of the mobile home park owner or operator which is not on a lot and is expressly used in the operation of the mobile home park such as for the park office, a community center, or park storage facilities.

Permanent Foundation
The U.S. Department of Housing and Urban Development (HUD) defines permanent foundation systems as a foundation that has:
  1. A permanent skirting around the perimeter to protect the foundation from vermin and weather.
  2. Permanent (concrete) piers to support the structure, including frost protection of those piers.
  3. Anchorage from the home to the foundation to resist loads caused by wind and earthquake forces.

Permit to Operate
A permit issued annually by the enforcement agency authorizing operation of a mobile home park.

A vertical support constructed of concrete, steel, or concrete masonry block (CMU) for the transmission of loads from a mobile home unit, accessory building or structure, or building component, to a footing. A pier does not include the footing.

A freestanding, outside walking platform, having a floor or deck surface elevated more than eight (8) inches above grade.

Private Fire Hydrant
See "Fire Hydrant, Private".


Any freestanding roof, or shade structure, installed or erected above a unit or accessory building or structure or any portion thereof.

An accessory structure providing a sloping path of travel, intended for pedestrian traffic.

Recreational Vehicle
A vehicle which includes a park trailer that is considered personal property and not real property.

Registered Owner
A person registered by the appropriate department as the owner of the mobile home unit.

Retaining Wall
A wall designed to resist the lateral displacement of soil or other materials.

To furnish with new or modified parts or equipment not available or considered necessary at the time of manufacture. In mobile home retrofits it generally means installing tie-downs or anchors, constructing concrete footings and piers, or maybe installing a skirting around the mobile home unit.

A thoroughfare for vehicular traffic within a mobile home park.


Sanitation Station, Recreational Vehicle
A plumbing receptor designed to receive the discharge of sewage holding tanks of self-contained recreational vehicles and which is equipped with a water hose connection for washing the receptor.

Sewage Drain Lateral
That portion of the mobile home park sewage system that extends to an individual lot drain inlet.

Sewage Drainage System
All the piping within or attached to the mobile home unit or accessory building or structure that conveys sewage or other liquid wastes to the drain outlet.

Sewer, Park
That part of the mobile home park sewage drainage system beginning at the lot drain inlet or from a point two feet downstream from a permanent building drain connection and terminating at the public sewer or private sewer disposal system.

Material used to enclose or partially enclose the area under the mobile home unit.

A step or any configuration of steps or risers where the run (length) of an individual tread or step does not exceed thirty (30) inches, and which is designed to enable passage from one elevation to another.

Standard Plan Approval (SPA)
A plan approved by the governing department for an accessory building or structure, an engineered tiedown system, or a mobile home foundation system, to be installed or constructed on a repetitive basis, for the purpose of obtaining a construction permit through an enforcement agency.

Steel Pier
A steel support that incorporates into its structure an adjustable means of raising and leveling the mobile home unit or accessory building or structure that the pier supports.

The entire pier and footing assembly, used to transfer the loads of a mobile home unit, accessory building or structure, or building component to the ground.

Support System
A system of supports, which sustains the vertical loads of a unit, accessory building or structure, or building component. A support system does not necessarily include a foundation system.


Technical Service
The providing of interpretation and clarification by the enforcement agency of technical data and other information relating to the application of mobile home foundation plan approvals and designs.

Tensioning Device
A mechanical device that is part of a tiedown assembly. The tensioning device allows a person to eliminate any slack in the tiedown assembly and maintain the tension established when the slack is eliminated.

Testing Agency
An organization which:
  • Is in the business of testing equipment and installations.
  • Is qualified and equipped for such experimental testing.
  • Is not under the jurisdiction or control of any manufacturer or supplier for any affected industry.
  • Maintains at least an annual inspection program of all equipment and installations currently listed or labeled.
  • Makes available a published directory showing current listings of manufacturer's equipment and installations which have been investigated, certified and found safe for use in a specified manner and which are listed or labeled by the testing agency; and
  • Is approved by the governing department.

Tiedown Assembly
An assembly of component parts that has been tested and listed by agencies approved by the governing department as complying with the requirements for the anchoring of mobile home to the foundation system.

Tiedown System
A tiedown system is used in conjunction with a support system and consists of the total number of tiedown assemblies required to provide a mobile home or mobilehome with resistance to wind loads.


A manufactured home, mobilehome, a multifamily manufactured home, or recreational vehicle.


Vapor Barrier
A vapor barrier is used to prevent or limit the amount of moisture which may rise upward from the ground through a crawlspace area. A vapor barrier is desirable when people and/or animals are intended to inhabit an area on a regular basis. It helps ensure proper insulation and function for surfaces such as tile, carpet, etc. It also prevents condensation from building up and also helps to deter mold.

A failure to conform to the requirements, or any other applicable provision of law.

Violation, Maintenance
A violation discovered during a maintenance inspection.


Water Main, Park
That portion of the water distribution system which extends from the main, water meter, or other source of supply to the branch water service lines.

Working Days
Generally speaking, it is all days except Saturdays, Sundays, and applicable local, state and federal holidays.

Work performed to the acceptable quality of generally recognized industry standards that does not compromise strength, function, or durability.