D.C. Mun. Regs. tit. 24, r. 24-218
A vault may be altered, repaired, or replaced only under permit obtained and issued in accordance with applicable provisions of this chapter.
Where a new building is to be erected on property adjoining an existing vault, and the vault space is to be used immediately or shortly for the construction of a new vault, the existing vault may be sealed by construction of a solid masonry wall separating it from the private property.
In the case of a replacement vault under § 218.2, the vault agreement and insurance shall remain in effect, and full responsibility shall rest on the owner. No rent, however, shall be charged for the space until the new vault is constructed, subject to the provisions of §§ 218.4 and 218.5.
If construction on the new building has not been started within six (6) months following the construction of the sealing wall, rent shall again be charged for the space occupied by the sealed vault at the previous rate until construction is started.
If construction is suspended after starting, and remains suspended for six (6) consecutive months, rent shall be charged as provided in § 218.4 during the remainder of the period of suspended construction.
D.C. Mun. Regs. tit. 24, r. 24-218