In the effort to make home building more sustainable, builders have to think about what they throw away in addition to what they create.
The Environmental Protection Agency found that in 2014, construction generated nearly 29 million tons of debris. The construction and demolition of buildings generated nearly 166 million tons of debris.
Construction sites are one the biggest offenders in generating waste. A report by UK-based Waste & Resources Action Programme (WRAP) found that construction waste can be reduced by up to 90% with offsite building methods by reducing packaging materials like wood pallets, plastic and cardboard, as well as broken bricks and tiles.
A 2017 report by Dodge Data & Analytics found 97% of single-family builders have practices in place to reduce waste on job sites.
Prefabrication and modular building can help reduce waste by using materials more efficiently.
Jason Davis, president of Colorado Modular Homes, says that the limitations of modular building are exactly what make it more efficient.
Modular-home dimensions are standardized, he told Colorado Builder, because the factories they are constructed in are set up to build them that way.
“We cater our designs to meet those dimensions, which can be a little difficult, but that’s where the efficiencies really come in. We’re not creating unnecessary corners and curves in our houses,” he explained. “There’s very little waste on a factory floor because of this.”
Colorado Modular Homes started as a spec home builder 12 years ago in Grand County, but now primarily builds system-built homes in places like Breckinridge and Vail.
Davis and his company focus on higher-end systems than what are commonly associated with modular building, though.
“Modular homes can be fairly simple, basic structures,” he said. “We challenge that model and do things that are more unique.”
Offsite construction can also help reduce the kind of human error that results in a lot of scrap material.
“When you’re stick-building a house out in the field, you’re going to be wrong. You’re going to make mistakes,” Davis noted.
Even if builders don’t go full mod, using prefabricated components in some of their processes can help reduce waste. The Dodge report found 95% of single-family builders and 90% of multifamily builders are using prefab components on jobs.
In addition to creating less waste, modular homes are naturally suited to meet energy efficiency standards.
The walls and floors are built on giant steel jigs so they’re perfectly square, Davis explained. When the walls are framed, “the dry wall is applied first, then it’s set up on your floor system.”
“What’s great about that is you’re able to build the house from the inside out, rather than from the outside in,” he said. “The walls are erected on these modules, and they’re able to insulate from the back side. Any penetrations for outlets or switches, we can seal from the outside, and then it can be insulated from the outside before the sheeting goes up, which can make a huge difference in terms of air infiltration.”
He continued, “When you’re building in the field, you build the outside first, and then you have to work your insulation and then your drywall, and that makes it a lot more difficult to seal for air infiltration.”
For builders and homeowners who want an energy efficient home, and also want to reduce their impact on landfills, modular building makes a lot of sense, Davis said.
“Anything done in a controlled environment where you take out a lot of the environmental factors that you deal with in the field, it’s just by its nature going to make things more efficient,” he said.