11:16 A gatehouse is a small building occupied by a watchman. A balcony is a type of outside porch that goes up to a higher floor, like you see in motels. Structures such as these do not require mezuzos, as they are not designed or fit for serving as residences The same is true of gardens and corrals. However, if a house or other building that requires a mezuzah opens up to such a structure, it would require a mezuzah. Therefore, gates that open up to courtyards, alleyways, cities, etc. require mezuzos because of the houses that open up to them. Not only that, if ten consecutive houses open up one to the next in a row, even if only the innermost one is of dimensions that would require a mezuzah, all of them require a mezuzah for its sake. Some authorities do require gatehouses and balconies to have mezuzos, therefore one should be installed without reciting the bracha.
11:17 Bathhouses, tanneries and mikvas do not require mezuzos because they are not suitable to serve as proper residences. However, barns, silos, wine cellars and other such storage areas do require mezuzos if they are of the requisite size. Some authorities, however, do not require mezuzos on such structures.