Don't mean to be a party pooper here, but as far as I was aware, congregations did not make decisions themselves to build Kingdom Halls and did not do the planning or construction work on their own. Decisions were obviously made at a branch level based on CO or DO recommendations; I don't know who applied for local authority planning permission, but the regional building committees then probably took over the task of funding and actually building the premises. Yes, they relied very heavily on volunteer labour and donations from local congregation members, but those local JWs had not actually caused the hall to come to be.
You're pretty late to the party.