As people and money pour into thriving cities and blight spreads through others that struggle, an increasing number of old homes are crunched by the excavator and dumped in the landfill. Asbestos-wrapped ducting goes undiscovered inside walls, lead is hidden in layers of paint, and when the excavator shovel comes crashing down, a wide array of toxic substances are released as airborne dust. At the same time, valuable building materials go unrecovered, with a high cost in embodied carbon. None of these things is good for the health of people or the planet.

In 2016, pushed by neighborhood organizations tired of this kind of “crunch-and-dump” demolition, Portland, Ore. passed the nation’s first deconstruction ordinance, making piece-by-piece dismantling mandatory for all homes built before 1916. In January 2020, the cutoff year was expanded to 1940. So far, more than 300 homes have been deconstructed in the city.

The rules are simple and the benefits far-reaching. The ordinance prohibits the use of heavy machinery for the structural work and requires that it be done by a city-certified deconstruction contractor, who must submit receipts for the donation, sale, or proper recycling and disposal of all materials. This guarantees a process that creates less dust, enables more-effective abatement of hazardous materials, and allows valuable materials to be salvaged for reuse.

By all accounts, Portland’s program has been a success, keeping neighborhoods quieter and healthier, reducing the waste stream, feeding the city’s retail reuse marketplace, and creating a new category of skilled labor. More importantly, the idea has caught the attention of municipalities across North America, many of whom have connected with Portland for advice and guidance, and launched deconstruction programs of their own.

The problems with mechanical demolition

Traditional demolition is generally seen as unskilled labor, to be accomplished in a day or two by the…