A building's extension is a wing. As in, "The hospital is adding a wing".
Or, "They named it 'The Gonzo Wing' because Gonzo funded it".
Structure, Construction, Edifice, or Erection.
Other words for structure are composition, arrangement, shape, form,or building.
erecting ;) also: structure or constructing based upon the definition of building.
These are synonyms for the word bridge: arch, bond, branch, catwalk, connection, extension, gangplank, link, overpass, platform, pontoon, scaffold, span, tie, transit, trestle, viaduct and wing.
The noun 'annex' is a word for a building added on to a larger one; an auxiliary building situated near a main one; an addition that is made to a record or other document, an appendix. The word 'annex' is also a verb, meaning to take control of a country or region by force; to add as an extra or subordinate part of something.
Another word for a building extension is an "annex." An annex typically refers to an additional structure that is connected to or part of an existing building, often used to provide extra space or facilities. Other terms like "addition" or "wing" may also apply, depending on the context.
Another word for outhouse is privy.
An annex is an extension of or an addition to a building. A small room off of a main room is an annex, and attics are another type of annex.
extensors / extensor muscles
tug
Building is another word for barn. Additional synonyms include shed and stable.
a tower, a house, a shelter...
Edifice
Barn or shed.
extension to obey
You can plug an extension cord into another extension cord. A extension cord is to help make doing something easier.
Lodge , Fellowship Hall ,