Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.
About this service
The cost to build an ADU depends on factors like your foundation type, utility connection distances, interior finish choices, and whether you are doing a detached build or a garage conversion. We provide an exact pricing confirmed free on the call.
Frequently asked in Portsmouth
What is an ADU estimate like in Portsmouth?
What are accessory dwelling unit services in Portsmouth?
Are prefab ADUs a good option for Portsmouth?
What are homes with in-law suites in Portsmouth?
How affordable are affordable accessory dwelling units in Portsmouth?
What is an accessory dwelling unit massachusetts rule for Portsmouth?
What is local ADU construction like in Portsmouth?
Also serving nearby: Norfolk · Chesapeake · Hampton · Newport News · Virginia Beach
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Portsmouth — population 96,793; about 2,906 residents per square mile across 33.3 sq mi. ZIP codes covered include 23701, 23702, 23703, 23704, 23705, 23707, 23708, 23709.
Neighborhoods served in Portsmouth: Olde Towne, Churchland, Downtown Portsmouth, Cradock, Waterview — and every surrounding area.
Areas we serve
Browse by state, then city.
