ADUs & Home Additions in Clinton, Massachusetts

Yes. Since February 2025, Massachusetts law allows one accessory dwelling unit — up to 900 square feet or half your home’s floor area, whichever is smaller — by right in single-family districts. That means no special permit, no variance and no public hearing. You still need a standard building permit, and the project must meet setbacks and building code — we handle all of that under our license.

In Central Massachusetts, a bump-out runs $25,000–$60,000, a primary-suite addition runs $90,000–$180,000, an in-law suite or ADU addition runs $120,000–$300,000, and a second-story addition runs $150,000–$300,000+. Converting an existing basement or garage into an ADU usually costs less because the structure already exists. See our 2026 Home Addition Cost Guide for Worcester County for the full breakdown, then get your exact price in writing.

Converting space you already have. A basement ADU or a garage conversion reuses your existing foundation, walls and roof — the most expensive parts of any build. We evaluate ceiling height, egress windows, moisture control and utility connections at the feasibility visit and tell you honestly whether your space qualifies before you spend a dollar on design.

Plan for roughly 4 weeks of design and engineering plus 4–10 weeks of permitting before construction starts. The build itself runs 4–8 weeks for a bump-out, 12–18 weeks for a primary suite, 16–28 weeks for an in-law suite or ADU addition, and 20–32 weeks for a second story. You get a written schedule before day one.

Yes — long-term rental of a legal accessory unit is exactly what the state law was designed to enable, and in the Worcester County market a legal ADU commands meaningful monthly rent. Rules for short-term rentals vary and can change, so we recommend confirming current town policy before planning an Airbnb-style use. We build the unit to full dwelling code either way, so you keep every option open.

Yes. Homes in the local historic district — including the Walnut Street area where our own office sits — need Historic Commission review for exterior changes, which mainly shapes the materials, windows and rooflines you can use. We know the process, prepare the application, and design the addition so it blends with your home and the district instead of fighting them.

Usually not — and that’s a genuine Clinton advantage. Most of the town is served by municipal water and sewer, so the Title 5 septic upgrade that can add $15,000–$40,000 to additions in neighboring rural towns typically doesn’t apply here. If your property is one of the exceptions on septic, adding a bedroom can require a system upgrade — which is exactly why we confirm your connection first, before any design work.

Yes. Structural work like additions requires a Massachusetts Construction Supervisor License — we hold CSL #121166 along with our Home Improvement Contractor registration (HIC #214808), liability insurance and workers’ compensation. Our license cards and certificate of insurance are linked on this page so you can verify them yourself, and every permit is pulled under our license, never yours.

Sí. Atendemos a nuestros clientes en español e inglés — desde el estudio de factibilidad hasta la entrega del proyecto. Llámenos al (508) 925-0396.

Yes — and an honest contractor should tell you that upfront. New living space gets assessed, and your property taxes rise in proportion to the value added. For most owners the math still works strongly in their favor: the rental income from a legal ADU, or the cost you avoid by not selling and buying a bigger home at today’s rates, typically outweighs the tax increase many times over. For exact numbers, the Clinton Assessor’s office is the right call — but you should walk into this project with clear eyes, and now you have them.

No. The 2025 state law specifically bars towns from imposing owner-occupancy requirements on by-right ADUs — a major change from the old in-law-apartment rules, and one of the reasons ADUs became genuinely attractive as long-term rental property. You can live in the main house and rent the ADU, do the reverse, or eventually rent both under Clinton’s normal rental rules. We build every unit to full dwelling code so all of those options stay open.