ADUs are allowed in CandiaTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Candia, NH
Is your property eligible for an ADU?
# of Properties
1,681
Owner-occupied
70%
Zoning districts
10
Avg Home Value
$485,675
Median Lot Size
3.24 acres
Avg Income
$128,665
Residential Types:
1,681 housing units
Single Family
85%
Apts (4+ units)
2%
Other
14%
Zoning Districts:
1,886 parcels · 10 districts
R
88%(1,659)
C
7%(123)
CL
2%(45)
MU
1%(23)
Other
2%(36)
ADU Rules
What can you build in Candia, NH?
Candia, NH follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: By Right
- –Detached ADU: By Right
Interior / Attached ADU Size Limits
- –Maximum internal ADU size of 850 sq ft.
- –Maximum internal ADU size of 75% of the primary dwelling’s floor area.
Detached ADU Size Limits
- –Maximum size of 850 sq ft for a detached accessory dwelling unit.
- –Maximum size of 75% of the primary dwelling’s square footage.
Max Units
- –2 ADUs per single-family lot; max 1 detached.
- –Second ADU requires a Special Exception.
Owner Occupancy
- –Owner must occupy either the principal or ADU
Parking
- –2 off-street spaces per ADU; on-site parking required for the main dwelling and any ADUs per Article IX; loc/size rules (≥10 ft from lot lines; 9x18 ft spaces) do not apply to one-family dwellings; no transit-based reductions.
Rental Restrictions
- –Short-term/boarding rentals not to exceed 184 consecutive days; allowed by Special Exception in the Residential (R) district and by right in the Mixed-Use (MX) district
ADU State Law
What can you build in New Hampshire?
- –New Hampshire ADU rules after HB 577 (signed July 15, 2025, eff. July 1, 2025 – Chapter 197).
- –One ADU, attached or detached, is allowed By Right on every single-family lot in any zoning district that allows single-family homes.
- –If the local ordinance is silent, the same By Right rule applies. You just need a building permit.
- –Default maximum is 950 sq ft of living space
- –Towns may set a lower maximum, but no lower than 750 sq ft,
- –Town may set a higher maximum
- –If a town specifies a size limit only for Internal or Attached ADUs and is silent on Detached units, we interpret that the state default maximum of 950 sq ft applies to Detached ADUs, since local limits apply only to the types they explicitly regulate.
- –Local zoning rules for ADUs can't be stricter than those for single-family homes, including lot size, frontage, and setbacks.
- –May require up to one additional parking space for each ADU.
- –Owner-occupancy: A town may require the owner to live on the property, but can't say which unit the owner must occupy. No requirement that ADU occupants be related to the main-house occupants.
- –Water & septic: The town can't demand a bigger system than the state DES rules require. Separate systems aren't mandatory, but you must upgrade if the existing one fails or lacks approval.
- –Conversions encouraged: Existing structures (e.g., garages, barns, etc.) may be converted even if they violate current setbacks or lot-coverage limits, and towns can't block a separate electrical panel/service for the ADU.
- –A town may bar ADUs on leased land or on lots with multiple attached single-family dwellings (e.g., townhouses).
What's allowed on your lot?
These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.
Check my propertyHow can we help you?
Get matched with trusted local builders
Understand what's allowed on your property
Learn the key rules and size limits for ADUs
Is your property eligible for an ADU?
ADU rules in other New Hampshire municipalities
Rules change at the town line. Check the municipality your property is actually in.
Rockingham County