The lists are the first stage in a strategy to establish partnering arrangements and avoid potential skills shortages caused by the construction of GCHQ in Gloucester.
It followed a best-value review of contracts carried out last year when local clients, such as headteachers, said they preferred the flexibility of working with local builders and consultants.
The small builders will operate on an hourly rate rather than the schedule-of-rates system used before, which clients found confusing. The scheme has been accepted by the Movement for Innovation as a demonstration project on delivering best value.
The scheme replaces the five-year management deals the council had with WS Atkins, which ran architectural services and contractor Mears, which managed construction services.