Park Construction and Alterations

There are multiple steps involved when constructing a new or altering an existing mobilehome or special occupancy park. There are both state and local government requirements to meet and approvals to obtain. Alterations to an existing utility system, facility, or permanent building within a park require a Permit to Construct from the enforcement agency.

Below you will find information needed to help you navigate the park construction and alteration processes.

Refer to the Park Construction Approval Booklet, HCD MP 514 (PDF) for additional information about your park construction process.

For additional information concerning plan and permit requirements, please contact either our Northern Area Office at NAOstaff@hcd.ca.gov or Southern Area Office at SAOstaff@hcd.ca.gov, or by phone at (800) 952-8356.

A construction permit is required when developing a new mobilehome park or special occupancy park or constructing additional spaces and/or facilities within an existing park. The following local government approvals and utility agency "will serve" letters must accompany all park construction project permit applications:

Note: The required written approvals may be in letter form issued by the agency having authority to grant such an approval or simply a signature on the affected plans by the approving agency's authorized agent.

Plan(s) must be drawn to scale and be of sufficient clarity to indicate the nature and extent of the construction proposed. Provide detailed drawings conforming to the provisions of the California Code of Regulations, title 25, chapter 2, and all applicable laws, ordinances, rules, and regulations. The first sheet of each set of plans must give the location of the proposed construction, name and address of the owner, and name of the person preparing the plans. 

Plot Plans must include the following information:

  • Site location with north arrow.
  • Address of proposed construction or reconstruction.
  • Name and address of owner(s).
  • Name and address of person(s) preparing plans.
  • Index of sheets on title sheet.
  • All required local approvals, Environmental Impact Report, or negative declaration.
  • The identification of all property lines, adjacent property lines, and mobilehome/RV lot lines.
  • Dimensions of all mobilehome/RV lots.
  • Method of permanent lot line identification including corner markers, lot numbers, and/or other means of identification.
  • Easements and/or right-of-ways, public or private, if any.
  • Location and size of all permanent buildings, parking spaces, and storage areas.
  • Schedule of manufactured/mobilehome size for individual lots.
  • Roadway widths and location of no parking signs.

Drainage and grading plans must include the following information:

  • General vicinity map of the proposed site.
  • Property limits and accurate contours of existing ground, details of terrain, and area drainage.
  • Limiting dimensions, elevations, or finish contours achieved by grading, proposed drainage channels, or other related construction.
  • Detailed plans of all surface and subsurface drainage devices, walls, cribbing, dams and other protective devices constructed with, or as part of, the construction, and a map indicating drainage area(s) and estimated runoff of the area served by any drains.
  • Location of buildings or structures on the property where the construction is to be performed. Identify location of any buildings or structures on property of adjacent owners which are within 15 feet of property, or that may be affected by proposed grading operations.

Grading notes must be shown on plans:

  • Include soils report with the plans.
  • The procedures relating to excavation, grading, and earthwork, including fills and embankments, are contained in the California Building Code.
  • The design engineer must provide a letter upon completion of the grading, certifying that the final grades are in compliance with the approved plans.
  • The soils engineering firm must conduct field observations and tests during construction to verify the quality of the work, conformance to the specifications, and recommendations contained in the soils report.
  • Upon completion of the grading, the soils engineer must submit a final report including test results, certifying the construction is in compliance with the specifications/plan(s) and recommendations contained in the soils report.

The Soil and Engineering Report must include the following:

  • Data regarding the nature, distribution, and strength of existing soils, and conclusions.
  • Recommendations for grading procedures.
  • Design criteria for corrective measures, if necessary.
  • Recommendations, if any, covering adequacy of sites to be developed by the grading.
  • Recommendations included in the report and approved by the building official must be incorporated in the grading plans or specifications.

The Engineering Geology Report must include the following:

  • An adequate description of the geology of the site.
  • Conclusions and recommendations regarding the effect of geologic conditions on the proposed development.
  • Options and recommendations covering the adequacy of sites to be developed by the proposed grading.
  • Recommendations included in the report must be incorporated in the grading plans or specifications.

Detail on the Utility Trenches must include the following:

  • Location of all utility trenches.
  • Depth of trenches.
  • Width of trenches.
  • Location and spacing of utilities within trenches.
  • Types of bedding and covering for utilities.
  • Protection and backfill of trenches.

Fire Protection Plans must include at least the following information:

  • Location of fire hydrants.
  • Type and manufacturer of hydrants.
  • Location and type of shutoff valve(s).
  • Location of thrust block size schedule.
  • Water flow duration time, gallons per minute (expressed as GPM), and required pressure.
  • Approval signature of local fire protection agency for fire protection provisions. Include with the approval, duration time, GPM, and required pressure data.

Electrical Distribution System/electrical plans/electrical calculations must include the following specifications:

  • Specifications of park service equipment and manufacturer.
  • Specification of the voltage, ampere and interrupting capacity rating, type and class of the overcurrent protective device in the park service equipment.
  • Ambient temperature design based on California Code of Regulations, title 25, section 1142.
  • Specify voltage, ampere, and interrupting capacity rating, type and class of overcurrent protective device for the primary system feeders and/or transformers.
  • Specify type of conductors, i.e., CU or AL; type of insulation; voltage rating; and temperature rating.
  • Provide specifications for transformers and unit substations.
  • Specify primary and secondary voltages, KVA ratings, and impedance of transformers.
  • Provide specifications for secondary distribution panel boards or that portion of the unit substations.
  • Specify voltage, ampere and interrupting capacity rating, type and class of the overcurrent protective devices for the secondary system feeders.
  • If the system is installed or owned by a utility company, provide a letter confirming such service, including information regarding the point of termination.
  • Complete electrical specifications, plans, and calculations are required if the point of termination does not comply with California Code of Regulations, title 25, section 1184.

Electrical Plan details must include the following:

  • Single line diagram of park electrical system, including the park lighting system.
  • Indication of location(s) of all equipment devices and conductors in the system.
  • Indication of circuit length, conductor size, and distance to center of load.
  • Details of conduit installation and size.
  • Details of conductor installation.
  • Details of equipment installation and mechanical protective barriers, if required.
  • Details of correct method of grounding system and equipment.
  • Details of park lighting installations.
  • For systems exceeding 230 volts, the signature of a California registered engineer.

Electrical Distribution System plan calculation details must include the following:

  • Load calculations for all loads served, not to exceed a total combined voltage drop of 5 percent for any total run.
  • All buildings in load calculations.
  • Written evidence from the serving utility indicating the available fault current at the park service.  (See New Park Construction - Local Government and Utility Agency Approvals above.)
  • Calculations utilized to determine interrupting capacity of overcurrent protective devices for each transformer.
  • Calculations used to determine interrupting capacity of overcurrent protective devices for secondary system feeders.
  • Park lighting calculations to verify compliance with California Code of Regulations, title 25, section 1108.
  • For systems exceeding 230 volts, the signature of a California registered electrical engineer.

Sewage Disposal System plans must include at least the following information:

  • If applicable, details of location and design of private sewage disposal system, including sizes of tanks, distribution boxes, and drain fields.
  • A signature of approval from the local health department. (See New Park Construction - Local Government and Utility Agency Approvals above.)
  • Size, length, and grade of sewer lines.
  • Type of pipe, manufacturer, pipe identification numbers, fittings, and location of pipe.
  • Location of cleanouts and vents.
  • Details of lot risers, p-traps (if any), venting, and protection of traps, mobilehome connection details.
  • Location of sewer inlet on mobilehome lot.
  • Engineered structural design and calculations for any on-site construction of septic tanks and/or sewage lift stations. The signature of the responsible California registered engineer must be on the calculations.
  • Design of required sanitary dump station if any lots are not provided with sewer and water utilities.
  • Signature and stamp of professional engineer if system is in excess of 100 mobilehome lots.
  • Location and connection to public sewer system.
  • Signature and stamp of professional engineer when grades of the system are less than specified in section 1268 (b), or if park drainage system exceeds the fixture unit loading of California Code of Regulations, title 25, section 1268, table 1292-1.
  • A letter from the design engineer stating he/she verified grade of all sewer lines on the construction site must be submitted after installation and will provide the enforcement agency with evidence indicating the grade of the lines was inspected.
  • If applicable, design, construction, and installation of sanitary sewer lift stations and pressure lines. Include pump specifications, gate and back flow valves, engineered calculations for the force main and venting, and audio-visual alarm systems.

The Water Distribution System plans must include at least the following information:

  • If applicable, source and pressure of private water system and letter of approval from local health department. (See New Park Construction - Local Government and Utility Agency Approvals above.)
  • Source of water and pressure at source of water if from a public water district.
  • Type of pipe, manufacturer, pipe identification numbers, fittings, and location of pipe.
  • Location of connection to source, meter size, check valves (if required), pressure reducing valves (if required), pipe sizes, fittings, type, and material of pipe and fittings.
  • Details of service riser to each lot, size, material, valves, backflow preventers, and mechanical barrier protection if required.
  • For additions to existing systems, include psi at point of interconnection at system and size of water main at that point.
  • Water demand calculations.
  • Thrust block schedule per Uniform Plumbing Code, 1985 edition.
  • A complete single line diagram of the new and existing system.
  • Locations of service risers for each lot.
  • Water distribution system designed in accordance with 1979 Uniform Plumbing Code, Chapter 10, and Appendix A.

The gas distribution system plans must contain at least the following information:

  • If system is installed by a utility company, letter confirming such service and identification of point of termination. (See New Park Construction - Local Government and Utility Agency Approvals above.)
  • Indication of source of gas supply and pressure.
  • Calculations for demand and pipe sizes (California Code of Regulations, title 25, section 1230).
  • Length of gas piping system runs, location of runs and shutoff valves in runs, showing size transition locations in runs. If adding to an existing system, complete demand calculations with a single diagram of the existing and proposed system.
  • BTU demands of piping system.
  • Schedule of pipe size, manufacturer, and identification of numbers of pipe, protective coating, wrapping of joints, and method of assembly.
  • Detail of mobilehome lot service riser, wrapping, type, manufacturer of gas shutoff valve, regulator and/or meter installation, supports, location, and protective barrier, if required.
  • If system is Liquefied Petroleum Gas (LPG), indication of location and size of tank(s). LPG systems must comply with California Code of Regulations, title 25, section 1210.
  • If gas system is over eleven (11) inches, water column system must be designed by a professional engineer in compliance with Federal Regulations by installation of a cathodic protection system (California Code of Regulations, title 25, section 1206). A report indicating evidence of compliance with Code of Federal Regulations, title 49, parts 191 and 192, and California Code of Regulations, title 25, section 1206, must be provided by a qualified person prior to final approval of the gas system.

Permanent Buildings

Swimming Pools

Public swimming pools constructed within a park must comply with the requirements of California Code of Regulations, title 17, section 30740.

Information Bulletin 2022-03 (MP, SOP) (PDF) provides notification that the California Department of Housing and Community Development has adopted Chapter 31B, Public Swimming Pools, of the California Building Code which provides standards for the installation, renovation, alteration, addition, relocation, and replacement of a public swimming pool or its ancillary facilities, mechanical equipment, and related piping.

Prior to altering an existing utility system, facility, or permanent building within a park, you must obtain a Permit to Construct from the enforcement agency. Where the Department is the enforcement agency, an Application for Permit to Construct, form HCD MP 50 (PDF), must be submitted (via email to NAOstaff@hcd.ca.gov or SAOstaff@hcd.ca.gov, by mail, or in person) to the Department and accompanied by appropriate plans depicting the proposed construction project and the prescribed fees. Please note: Large format plans cannot be accepted via email. These must be submitted by mail or in person.

Plan(s) must be drawn to scale and be of sufficient clarity to indicate the nature and extent of the construction proposed. Provide detailed drawings conforming to the provisions of the California Code of Regulations, title 25, chapter 2, and all applicable laws, ordinances, rules, and regulations. The first sheet of each set of plans must give the location of the proposed construction, name and address of the owner, and name of the person preparing the plans.

For additional information concerning plan and permit requirements, contact either the Northern Area Office at NAOstaff@hcd.ca.gov or (800) 952-8356 or the Southern Area Office at SAOstaff@hcd.ca.gov or (800) 952-8356.

The applications below can be submitted to the Department via email to:

Exception: HCD does not accept large format plans via email. These plans must be submitted by mail or in person.

When submitted to HCD, the completed application must be accompanied by the appropriate fees. Payment must be in the form of a check or money order payable to the Department of Housing and Community Development. Payments can also be submitted through the Department’s online fee-payment system. Please note: you must have a DTN and a zip code to make a payment online. This information can be obtained by contacting the appropriate Area Office at (800) 952-8356 or NAOstaff@hcd.ca.gov or SAOstaff@hcd.ca.gov.