An On-Site Look at Off-Site Construction

Some builders are turning to walls and roofs built in a factory rather than framed on site, an approach called off-site construction. It covers a range of methods, from basic stick-framed wall sections to panels that arrive with windows, exterior weather barrier, insulation, and even drywall already in place. A recent example is a home in southern New England built to the passive house standard, an approach focused on very high insulation and airtightness to cut energy use. Its walls and roof used 20-inch-thick structural panels insulated with straw, made by a Maine manufacturer, reaching an insulation value of roughly R-70.

Builders who have used these panels say they can speed up construction, keep the house better protected from weather during the build, and make it easier to seal the home tightly against air leaks, which matters most in cold-winter regions. Straw insulation was chosen partly to lower the embodied carbon of the build, meaning the carbon emissions tied to producing and shipping materials, and to use more locally sourced products.

Factory-built panels aren't automatically cheaper or simpler, though. They come with added costs, the need for careful upfront planning, and logistical hurdles in getting large panels delivered and set. For homeowners planning a new build or a major addition, off-site construction is one path toward a highly efficient, well-sealed home, but it's not a fit for every project.