Cape Cod Hemp House

With simple gabled roofs and shingle cladding, the Cape Cod Hemp House is like a low-carbon trojan horse. The home sits in the quaint Harwichport seaside town surrounded by cape-style cottages. Behind the shingles, the house uses a combination of new and old building methods to model a future free of the pervasive use of petroleum-based plastics.

To eliminate petroleum-based foam insulations in a high-performance coastal home, the team utilized an integrated design process. Early meetings were held with the owner, design team, energy and structural consultants, and hemplime specialists.

Hemplime fills twelve-inch-thick walls and sixteen-inch-thick roofs, insulating the house and sequestering over 21,000kg of CO2 emissions. The embodied carbon of the home is 50% of a conventionally built equal, primarily through the use of hemplime and low-cement concrete which further reduced approximately 8,000kg CO2 emissions. The all-electric house is designed to be net-zero, all while nearly eliminating the use of plastics in the building envelope.

Foams in the walls are replaced by a mix of hemp hurds, lime, and sand that contributes to fire-resistance rather than fire-toxicity. Plastic foam and crushed rock under the building is replaced by recycled glass aggregate (saving an estimated 3,000kg of CO2 emissions compared to a conventional EPS foam insulation). Plastic foam on the roof is replaced by super-insulating vacuum panel insulation. Adhesive or staple on building wrap is replaced by repairable lime-plaster.

The hemplime installation was completed with a French low-water / high-yield spray application process enabling completion in a fraction of the time of typical hand placed methods. Lime plasters from Canada finish the inside of the house, resulting in finishes that are breathable, repairable, and beautiful. The plaster and hemplime regulates humidity and temperature swings in the house, and eliminates use of paints and preservatives in conventional building that would otherwise pollute the interior air.

The hemplime was left exposed on a basement wall, and the lime plaster was sculpted into art on the entry wall. These art walls express the materials and care with which we might approach home building if our future is to continue. The house fights climate change and pioneers a future for more durable, beautiful, holistic homes.

Category:Private HomesYear:2023Location:Harwichport, MAArchitects:Adam Titrington and Peter Twombly/Estes Twombly + Titrington Architects, Inc.Lead Architects:Adam Titrington and Peter Twombly/Estes Twombly + Titrington Architects, Inc.Design Team: Adam Titringon and Peter TwomblyContractor:CH Newton BuildersClient: Michael MonteiroPhotographer: Estes Twombly + Titrington Architects, Inc.; DuChanvre