The phrase "ancillary structure" is correct and usable in written English.
It can be used in contexts where you are referring to a secondary or supporting structure that serves a supplementary role to a primary structure.
Example: "The building's design includes an ancillary structure that houses the maintenance equipment."
Alternatives: "supporting structure" or "secondary structure".
At some point, the shed may be an ancillary structure.
On a large site at 26th Street and 11th Avenue owned by the Moinian Group, the M.T.A. plans to build a seven-story ancillary structure for that line.
The chief financial officer, Brandon S. Pederson, spoke glowingly of the "new ancillary structure" that helped bolster profits and brace against increased competition in Seattle from the aggressive Delta Air Lines.
Furthermore, we optimize the operating conditions and ancillary structure of the counter-current integrated process, achieving a total annualized cost reduction of 72.2% with respect to the conventional design.
In addition to the original building, there is also an annex built in 1993, an ancillary structure housing office security services and a bomb shelter predating the 1990s.
The apparently conflicting ontogenetic trend seen in the genital appendage therefore is due to the appendage not being the sexual organ itself but rather an ancillary structure that follows the development trend of the endopods from which it is derived, while the gonopores, which it overlies, may not fully develop until the final moult, as would be expected.
Plain adhesive bonding applicable for ancillary structures as well as innovative hybrid joining concepts promising considerable structural advancement are also introduced in this chapter.
Large mosques were usually built with ancillary structures.
The church, its ancillary structures, and its garden occupy three blocks from Amsterdam Avenue to Morningside Drive, between 110th and 113th Streets.
There are three such pairs still standing, and although the mansions have survived intact, two of the three ancillary structures have been radically altered with added floors.
On 17 acres bought by the railroad, 120 houses, three churches, two hospitals and an orphan asylum would have to be obliterated, as would the stables, warehouses and other ancillary structures.
