Decks & Porches in Cohasset, Massachusetts

Decks and porches are not eligible for Mass Save energy rebates. Cohasset is served by National Grid for electricity, an investor-owned utility in the Mass Save program, but outdoor structural construction is not a covered category.

The more consequential local factors are the Wetlands Protection Act and the Historic District Commission. Cohasset's coastal location means many residential parcels fall within 100 feet of coastal bank, tidal flats, or salt marsh, all protected resource areas requiring a Notice of Intent with the Cohasset Conservation Commission. The 200-foot riverfront protection zone also applies along Bound Brook and other perennial streams. For properties within the Cohasset Town Center Historic District, exterior additions including porches and decks visible from the street require Historic District Commission review before a building permit is issued.

File with the Cohasset Building Department before any attached or elevated deck. State code (780 CMR) requires 48-inch frost-depth footings (Plymouth/Norfolk coastal frost line), ledger flashing, and 36-inch guardrails with baluster spacing under 4 inches. Parcels near Cohasset Harbor, coastal bank, or tidal wetlands need Conservation Commission approval under the Wetlands Protection Act. Properties in the Town Center Historic District also need Historic District Commission sign-off for any exterior change.

Where a permit is required, decks & porches work in Cohasset is filed with the Cohasset Building Department; see the Cohasset Building Department’s contact, portal and who pulls the permit on permits.llc.

Deck costs in Cohasset run above the South Shore average because of high-demand contractor market, the premium for salt-air-appropriate materials, and the additional regulatory steps common for coastal and historic-district lots. A full-PVC deck (Azek) typically runs $38,000 to $62,000 installed for an average Cohasset lot; composite (Trex Transcend, TimberTech) is $30,000 to $52,000; pressure-treated pine is $22,000 to $36,000 but requires more coastal maintenance. Conservation Commission filings add $1,500 to $4,000; Historic District reviews add further time.

Cohasset is a Norfolk County coastal town of about 8,330 residents with 3,290 housing units, a relatively small housing count that reflects the town's large lot sizes and low density. At a median home age of 66 years, many homes predate the 1960s, with a significant inventory of pre-WWII colonials, antique capes, and Victorian-era houses along Jerusalem Road and the harbor area.

Cohasset is bounded by Cohasset Harbor and the Atlantic Ocean to the east, with Scituate to the south and Hingham to the northwest. The coastal character means salt air, coastal bank protections, and tidal wetlands directly affect deck construction on a meaningful share of parcels. Cohasset also has an active Historic District Commission that reviews exterior changes in the town center historic district.