Cross Rip Development

File with the Nantucket Building Department under 780 CMR. Any attached deck requires a building permit with footing and framing inspections. Properties within the Nantucket Historic District need HDC approval for any exterior change before the building permit issues. Properties within 100 feet of coastal bank, harbor, pond, or mapped wetland, which covers much of the island, need a Conservation Commission Notice of Intent. Footings must reach 48 inches below grade. Guardrails on surfaces 30 or more inches above grade must be at least 36 inches tall with baluster spacing under 4 inches.

Deck and porch costs on Nantucket run significantly above all mainland Massachusetts benchmarks, driven by island freight costs, limited contractor availability, and permitting complexity. A 250-square-foot pressure-treated deck on Nantucket typically costs $25,000 to $40,000 installed. Cedar and mahogany are common material upgrades given the market preferences; composite decking at the same size runs $35,000 to $55,000. HDC and Conservation Commission filings add $1,000 to $3,000 in permitting costs and often six to twelve weeks to the schedule. Off-island contractors working on Nantucket must comply with island logistics and often add mobilization fees.

Massachusetts requires a written contract and a Home Improvement Contractor registration for most residential decks & porches work; ask for the registration number and check it before paying a deposit.

More on permits, costs, rebates and common questions, plus every other decks & porches contractor serving the town, on the Decks & Porches in Nantucket page.