Rehabilitation
(3) Rehabilitation(i) In general. For purposes of this paragraph, rehabilitation includes renovation, restoration, or reconstruction. However, the term rehabilitation does not include enlargement (within the meaning of paragraph (c)(7)(ii) of this section), new construction, or the completion of new construction after a building has been placed in service. For purposes of this paragraph (b)(3), whether expenditures are attributable to the rehabilitation of an existing building, or to new construction, is determined upon all the facts and circumstances. (ii) Substantial rehabilitation. For a building to be considered rehabilitated, the rehabilitation must be substantial. Whether a rehabilitation is substantial is determined upon the basis of all the facts and circumstances. In general, to be substantial, the rehabilitation must do one of the following: (A) Materially extend the useful life of the building; (B) Significantly upgrade its usefulness (for either the same or a new use); or (C) Preserve it in a way that significantly improves its condition or enhances its historic value. (iii) Aggregation of rehabilitation. In the case where qualified rehabilitation expenditures are incurred with respect to a rehabilitation of a building by more than one person (e.g., a lessor and a lessee, several lessees, or several condominium owners), the substantial rehabilitation requirement in this paragraph (b)(3) shall be applied by aggregating all the rehabilitation work done by such persons. (iv) Special rule by qualified rehabilitation expenditures treated as incurred by the taxpayer. In the case where qualified rehabilitation expenditures are treated as having been incurred by a taxpayer because of the application of paragraph (c)(3)(ii) of this section, the substantial rehabilitation test in paragraph (b)(3)(ii) of this section will be applied by aggregating the rehabilitation work done by the transferor and the transferee. (v) Examples. The provisions of this subparagraph (3) may be illustrated by the following examples: (4) Retention of 75 percent of external walls(i) In general. A building meets the requirements set forth in paragraph (b)(1)(iii) only if 75 percent or more of the existing external walls (as measured by the total area of the existing external walls) are retained in place as external walls in the rehabilitation process. For this purpose, the area of existing external walls includes the area of windows and doors. (ii) External wall. For purposes of this paragraph (b)(4), a wall includes both the supporting elements of the wall and the nonsupporting elements (e.g., a curtain) of the wall. Except as otherwise provided in this paragraph (b)(4), the term external wall includes any wall that has one face exposed to the weather, earth, or an abutting wall erected on an adjacent property. An external wall also includes a shared wall (i.e., a single wall shared with an adjacent building), generally referred to as a party wall. (iii) Alternative rule. Notwithstanding the definition of external wall contained in paragraph (b)(4)(ii) of this section, in any case in which the building being rehabilitated would fail to meet the requirements of a qualified rehabilitation building if the definition of external wall in paragraph (b)(4)(ii) of this section were used, then the term external wall shall be defined as a wall, including its supporting elements, with one face exposed to the weather or earth, and a common wall shall not be treated as an external wall. (iv) Retained in place. An existing external wall is retained in place if the supporting elements of the wall are retained in place. An existing external wall is not retained in place if the supporting elements of the wall are replaced by new supporting elements. An external wall is retained in place, however, if the supporting elements are reinforced in the rehabilitation, provided that such supporting elements of the external wall are retained in place. An external wall is retained in place even though it is covered (e.g., with new siding). Moreover, the existing curtain may be replaced with a new curtain provided that the structural framework that provides for the support of the existing curtain is retained in place. An external wall is retained in place notwithstanding that the existing doors and windows in the wall are modified, eliminated, or replaced. A wall may be disassembled and reassembled so long as the same supporting elements are used when the wall is reassembled. Thus, for example, in the case of the brick wall, the wall is considered retained in place even though the original bricks are removed (for cleaning, etc.) and put back to form the wall. (v) Retention as an external wall. For purposes of meeting the 75 percent requirement of this subparagraph (4), an existing external wall must be retained in place as an external wall. If an addition is made that results in an existing external wall being converted into an internal wall, the wall is not retained in place as an external wall. (vi) Special rule. Solely for the purpose of meeting the 75 percent requirement of this subparagraph (4), the walls of an uncovered internal shaft designed solely to bring light or air into the center of a building which are completely surrounded by external walls of the building and which enclose space not designated for occupancy or other use by people (other than for maintenance or emergency) are not considered external walls. Thus, a wall of a light well in the center of an office building is not an external wall. However, walls surrounding an uncovered courtyard which is usable by the building's occupants, (e.g., at lunch time) are external walls. (vii) Examples. The provisions of this subparagraph (4) may be illustrated by the following examples: (5) Major portion treated as separate building(i) In general. Where there is a separate rehabilitation of a major portion of a building, such major portion shall be treated as a separate building. Thus, such major portion may qualify as a qualified rehabilitated building if the requirements of this paragraph are met with respect to such major portion. Expenditures for property that services both a major portion of a building and another portion must be specifically allocated to each portion to the extent possible. If it is not possible to make such an allocation, the expenditures must be allocated to each portion on some reasonable basis. What constitutes a reasonable basis for an allocation depends on factors such as the type of improvement and how the improvement relates functionally to the building. For example, in the case of expenditures for an air conditioning system or a roof, a reasonable basis for allocating the expenditures would be the volume of the major portion served by the improvement relative to the volume of the other portion of the building served by the improvement. (ii) Major portion defined. Whether a part of a building constitutes a major portion of the building is determined upon the basis of all the facts and circumstances. A major portion must generally consist of clearly identifiable parts of a building (e.g., a wing of a building or the first 5 stories of a 7 story building). The following factors shall be taken into account: (A) Whether the portion comprises an entire leasehold interest or an entire ownership (e.g., condominium) interest; (B) Whether the portion (as measured by volume) is sufficiently large that it would be reasonable to treat it as a separate building; and (C) Whether the portion is functionally different from other parts of the building. (6) Special rule for rehabilitation done in phases. If rehabilitation which is not continuous is determined under this subparagraph to be a single rehabilitation done in phases, the requirements of this paragraph (b) are to be applied with respect to the overall rehabilitation and not merely to a phase of the rehabilitation. In such case, a phase of a single overall rehabilitation will not be considered as prior rehabilitation for purposes of subparagraph (2)(i)(B) of this paragraph (b). Whether rehabilitation which is not continuous is a single rehabilitation that is done in phases is determined on the basis of all the facts and circumstances. Generally, however, to constitute a single rehabilitation that is done in phases, there must exist, prior to the time any rehabilitation work is commenced, a set of written plans describing generally all phases of the rehabilitation of the building and a reasonable expectation that all phases of the rehabilitation will be completed. Such written plans are not required to contain detailed working drawings or detailed specifications of the material to be used. In addition, the period between the time that physical work on the first phase of the overall rehabilitation begins and physical work on the last phase of the overall rehabilitation begins must be reasonable. In determining whether the rehabilitation is completed within a reasonable time, the fact that a building is occupied during the rehabilitation, the necessity of acquiring a lease (of additional portions of the building), and unforeseen delays shall be taken into account. Other factors that are relevant in determining whether rehabilitation is a single rehabilitation include the length of time between each phase of rehabilitation activities and the extent of rehabilitation activity in each phase. (7) Special rule for adjoining buildings that are combined. For purposes of this paragraph (b), if as part of a rehabilitation process two or more adjoining buildings are combined and placed in service as a single building after the rehabilitation process, then all of the requirements of a qualified rehabilitated building in section 48(g)(1) and this section may be applied to the constituent adjoining buildings in the aggregate. Any party walls or abutting walls between the constitutent buildings that would otherwise be treated as external walls (within the meaning of paragraph (b)(4)(ii) of this section) would not be treated as external walls of the building; the substantial rehabilitation test in paragraph (b)(3)(ii) of this section would be applied to the aggregate rehabilitation work with respect to all of the constitutent buildings.