The Cape Cod Hemp House is situated in quaint Harwich Port, surrounded by quintessential cape-style cottages with simple gabled roofs and shingle cladding. The resemblance to its neighbors is only skin deep. Behind the shingles, the house demonstrates a future free of petroleum-based fuels and materials.

The house is configured in two parallel gables. The southern wing contains the main bedrooms, each having views of Nantucket Sound. Open living on the first floor extends to an outdoor deck with arbor. A seasonal sunshade limits summer heat gain, but allows plenty of winter light and passive heating. On the northern wing, the guest suite and workout room have smaller openings for privacy and to limit energy loss. The two south-facing rooftops enable enough photovoltaic area to supply projected electrical needs.

A variety of materials were used to create a durable, low-carbon, high-performance coastal home without petroleum foams. Recycled glass aero-aggregate was substituted for sub-slab foam. Foams in the walls and roof were replaced by a mix of hemp hurds, lime binder, and water. The hemplime sequesters over 21,000kg of CO₂ emissions and eliminates the need for plywood, drywall, and building wrap. Alongside low-cement concrete and other measures, total embodied carbon was reduced to 50% of a conventionally built equal.

The exterior of the house is clad in eastern white cedar shingles, wood windows, and zinc roofing. The landscaping is comprised of native plantings, a pollinator garden, clover lawn, reclaimed granite pavers and Appalachian black locust decking and pavers.

Natural lime plaster applied to the hemplime finishes the inside of the house. The hemplime remains exposed on a basement wall, and the plaster sculpted at the entry wall. These art walls express the materials and care with which the house fights climate change and pioneers a future for more durable, beautiful, holistic homes.

PROJECT TEAM

ARCHITECT: Estes Twombly + Titrington Architects (Adam Titrington, AIA, Peter Twombly, AIA)
STRUCTURAL ENGINEER: Structures Workshop (Erik Nelson, PE)
MECHANICAL AND ENERGY ENGINEER: ZeroEnergy Design (Jordan Goldman, CPHC)
HEMPLIME CONSULTING: AKTA – BVP (Laurent Goudet), Kiko Thebaud
HEMPLIME INSTALLATION: Hempstone, LLC, AKTA – BVP
CIVIL ENGINEERING: Ryder & Wilcox
INTERIOR DESIGN: Martha’s Vineyard Interior Design (Liz Stiving)
LIGHTING DESIGN: Light Insight Design Studio (Lana Nathe)
AV & LOW VOLTAGE: Josh Kiernen Technology Planning
ACOUSTIC CONSULTING: Cavanaugh Tocci Associates
LANDSCAPE ARCHITECT: Kimberly Mercurio Landscape Architect
GENERAL CONTRACTOR: C.H. Newton Builders (Zachary Miller)