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State law compliance deadlines
Several HAP zoning items are driven by state mandates — not optional policy. These cannot be deprioritized.
ADUs by-right citywide
HB 577 (eff. July 1, 2025) + Portsmouth March 2026 ordinance update. Detached and attached ADUs are now by-right. No CUP required.
Parking cap (SB 284)
Effective Sept 13, 2025. State caps parking at 1 space per residential unit. Portsmouth’s 1.3–1.5 space standard is currently unlawful.
Commercial conversions + multifamily in commercial zones (HB 631)
State will require multifamily allowed on commercially zoned land and automatic setback/height exemptions for adaptive reuse. Portsmouth must amend before July 1, 2026.
Single-family zones dominate Portsmouth’s residential land
The R, SRA, and SRB zones together cover 2,276 acres — 85.8% of all residential land in the city. These zones currently allow only single-family homes by-right. Virtually all missing middle housing requires a variance or is prohibited outright.
Any serious housing production strategy eventually has to engage Z-33 (single-family zone reform). The dependency note flags this requires anti-speculation groundwork first. But the scale of the problem should inform how the committee weights zoning category items overall.
Zone structure — the 10 zones that matter most for housing HAP
| Code | Name | Land share | Housing types currently permitted | Key HAP items |
|---|---|---|---|---|
| R Rural Residential |
Rural Residential | 5-acre min. lot |
SFH by-right ADU by-right Multifamily: prohibited | Z-8, Z-33 |
| SRA / SRB Single Residence A & B |
Single Residence | Together ~85% res. land |
SFH by-right ADU by-right 2-family: variance 3+: prohibited | Z-5, Z-8, Z-33 |
| GRA / GRB General Residence A & B |
General Residence | 7,500 sf min. |
SFH + 2-fam by-right ADU by-right 3–4 unit by-right 5–8: special exception | Z-5, Z-8, Z-26 |
| GRC General Residence C |
General Residence C | 3,500 sf min. |
SFH through 4-unit by-right 5–8: special exception 8+: prohibited | Z-5, Z-8 |
| G1 / G2 Gateway Mixed Use |
Gateway Mixed Use | Major corridors |
Broad housing by-right Density bonus: CUP Workforce bonus available | Z-6, Z-7, Z-12, Z-22, Z-23 |
| CD4 / CD5 Character Districts |
Character Districts (downtown) | Downtown core |
Mixed use by-right Multifamily by-right Form-based standards apply | Z-7, Z-11, Z-26, Z-35 |
| OR Office / Research |
Office Research | 3-acre min. |
Residential: currently prohibited HB 631 mandates change by Jul 2026 | Z-1, Z-3, Z-25, Z-29 |
| B / GB Business zones |
Business / General Business | Highway corridors |
Residential: CUP in B GB: residential limited HB 631 expands rights Jul 2026 | Z-3, Z-25, Z-29, Z-35 |
⚖ Simplified for triage orientation. Confirm specific parcel rules with the Planning Department or the plain English guide.
Approval pathway by housing type — current Portsmouth rules
| Housing type | R / SRA / SRB | GRA / GRB | GRC | G1 / G2 | CD4 / CD5 |
|---|---|---|---|---|---|
| Single-family | By-right | By-right | By-right | By-right | By-right |
| ADU (attached or detached) | By-right ★ | By-right ★ | By-right ★ | By-right | By-right |
| 2-family / duplex | Variance | By-right | By-right | By-right | By-right |
| 3–4 unit multifamily | Prohibited | By-right | By-right | By-right | By-right |
| 5–8 unit multifamily | Prohibited | Sp. exception | Sp. exception | By-right | By-right |
| 9+ unit multifamily | Prohibited | Prohibited | Prohibited | By-right | By-right |
| Cottage / cluster housing | No pathway | No pathway | No pathway | CUP | CUP |
| Coliving | Prohibited | Prohibited | Prohibited | CUP (B, G1, G2) | CUP |
★ By-right as of HB 577 (July 2025) + Portsmouth March 2026 ordinance update.
All 38 Z-items grouped by mechanism — click any to expand