(a) Substantial alteration. If the agency undertakes alterations to a PDP multifamily housing project that has 15 or more units and the cost of the alterations is 75 percent or more of the replacement cost of the completed facility, then the project shall be designed and altered to be readily accessible to and usable by individuals with disabilities. Subject to paragraph (c) of this section, a minimum of five percent of the total dwelling units, or at least one unit, whichever is greater, shall be made accessible for persons with mobility impairments. A unit that is on an accessible route and is adaptable and otherwise in compliance with the standards set forth in paragraph (d) of this section is accessible for purposes of this section. An additional two percent of the units (but not less that one unit) in such a project shall be accessible for persons with hearing or vision impairments. If state or local requirements for alterations require greater action than this paragraph, those requirements shall prevail.

(b) Other alteration.

(1) Subject to paragraph (c) of this section, alterations to dwelling units in a PDP multifamily housing project shall, to the maximum extent feasible, be made to be readily accessible to and usable by individuals with disabilities. If alterations of single elements or spaces of a dwelling unit, when considered together, amount to an alteration of a dwelling unit, the entire dwelling unit shall be made accessible. Once five percent of the dwelling units in a project are readily accessible to and usable by individuals with mobility impairments, then no additional elements of dwelling units, or entire dwelling units, are required to be accessible under this paragraph. Once two percent of the dwelling units in a project are readily accessible to or usable by individuals with hearing or vision impairments, then no additional elements of dwelling units, or entire dwelling units, are required to be accessible under this paragraph.

(2) Alterations to common areas or parts of facilities that affect accessibility of existing housing facilities, shall, to the maximum extent feasible, be made to be accessible to and usable by individuals with disabilities.

(c) The agency may establish a higher percentage or number of accessible units than that prescribed in paragraphs (a) or (b) of this section if the agency determines that there is a need for a higher percentage or number, based on census data or other available current data. In making such a determination, HUD shall take into account the expected needs of eligible persons with and without disabilities.

(d) The definitions, requirements, and accessibility standards that apply to PDP multifamily housing projects covered by this section are those contained in the UFAS, except where the ADAAG provides for greater accessibility for the type of alteration being undertaken, and, in this case, the definitions, requirements and standards of the ADAAG shall apply.

(e) With respect to multifamily housing projects operated by HUD, but in which HUD does not have an ownership interest, alterations under this section need not be made if doing so would impose undue financial and administrative burdens on the operation of the multifamily housing project.