Alternative Construction for Manufactured Housing

To encourage innovation and the use of new technology in the manufactured housing industry, the Department of Housing and Urban Development permits manufacturers to build homes in accordance with its Regulations (3282.14) titled “Alternative Construction of Manufactured Homes.” A manufacturer must request from the Department, an Alternative Construction (AC) letter for homes that do not conform to the requirements of the Manufactured Home Construction and Safety Standards (the Standards) at the time of shipment. Through alternative construction, HUD will permit manufacturers to use new designs or techniques not in compliance with the Standards in cases:

(1)  Where a manufacturer proposes to use construction that would be prohibited by the Standards;

(2)  Where such construction would provide performance that is equivalent to or superior to that required by the Standards; and

(3)  Where (i) compliance with the Standards would be unreasonable because of the circumstances of the particular case, or (ii) the alternative construction would be for purposes of research testing or development of new techniques or designs.

Overall, alternative construction requires HUD’s approval and close coordination by the manufacturer between the design approval agency (DAPIA), in-plant inspection agency (IPIA), and the State Administrative Agency (SAA). The manufacturer is also responsible to ensure that the purchaser/consumer is notified of the alternative construction methods applied to the home.

The AC process requires that the manufacturer submit to HUD information and drawings detailing the specific feature(s) they intend to construct that are in violation to the Standards. The Department reviews submitted documentation and determines if the proposed alternative meets or exceeds the safety and durability provided by the Standards. The approval normally requires notification to the purchaser or proposed purchaser of work that is being done and completion of an on-site inspection for work that is completed in the field. After the work and inspection is completed, the manufacturer must send an inspection report to HUD and provide a copy to the purchaser. In addition, the manufacturer must send cumulative quarterly status reports to HUD on homes built and inspected under each approved AC letter. Pursuant to HUD’s January 30, 2007 memo, 100 % inspection is required prior to occupancy.

Information presented on this website may provide manufactured home consumers with basic knowledge of alternative constructions provisions of the Manufactured Home Procedural and Enforcement Regulations, but the information is also geared to state and private agents of HUD that oversee the construction of manufactured homes and enforcement of these Regulations. An Alternative Construction home can be identified by the letters “AC” in the home(s) serial number. The serial number is located on the home’s foremost chassis cross-member and is also found on the home’s data plate. 

Common types of AC approvals

  • Vent pipe extensions through hinged roofs
  • Two story construction
  • Site installed siding
  • Deletion of insulation in any part of the home's thermal envelope
  • Shipment of home without a water heater
  • Dormer roofs
  • Accessible shower stalls
  • High slope roofs (Cape Cod Design)
  • Whole house ventilation
  • Roof ridge interconnection (e.g. hinged roof, ridge caps)
  • Tankless water heaters

Requests for Alternative Construction approval letters should be sent to:

U. S. Department of Housing and Urban Development
Office of Manufactured Housing Programs
451 Seventh Street, SW, Room 9168
Washington, DC 20410-8000


See Proposed Checklist for more information regarding submittal of an AC request.  Further information can also be found in the Regulations at 24 CFR §3282.14.