In 2014, the City of Minneapolis issued 184 wrecking permits, the vast majority of which were for single family homes. The demolition of a typical 2,000 square foot home generates approximately 127 tons of Construction and Demolition (C&D) waste. Nationally, C&D waste accounts for over 40 percent of waste by ton sent to landfills.
According to a City of Minneapolis report on house demolition in Minneapolis, “Green Building and Deconstruction Report” (March 2015):
In order to become a zero-waste city, or even to catch up with other U.S. cities exhibiting the highest recycling rates, Minneapolis must significantly reduce the amount of C&D waste that ends up in our region’s landfills.
Reducing the Cost of Demolition
Minneapolis City Councilperson Linea Palmisano led an effort to examine the state of green building — to lead to greater incentives in the construction and demolition of residential development for one to four unit buildings. This is the Part 2 summary of the report that resulted.
Other than encouraging the continued use of existing structures, three primary ways to reduce C&D waste sent to landfills from demolitions exist:
- intensive/structural deconstruction,
- salvage/non-structural deconstruction,
- C&D waste diversion.
Intensive deconstruction is particularly labor intensive. Building materials must be removed in a methodical fashion, with a large crew, to prevent damage and ensure safety of workers. Deconstruction of a single-family home takes approximately 20 days,compared to 1-3 days for traditional demolition.
While the increase in time and labor required to deconstruct a home results in significantly higher cost, resale of recovered materials can potentially make up for this additional cost, depending on market factors.
Salvage, or non-structural deconstruction, involves the removal of those components of a home that are most easily reused or are of a particularly high value, including electrical and plumbing fixtures, pipes, doors, millwork, and hardwood floors.
In order to be salvageable, materials must be in good condition and there must be enough demand for used building materials retailers, architectural salvage companies, or antique stores to be able to sell the product. In some cases, considerations must be made to ensure that salvaged products meet current code requirements.
- The typical 2,000 square foot home can contain up to 6,000 board-feet of reusable lumber.
- SB sheathing and vinyl siding are more difficult to reuse than traditional wood siding or masonry.
- Hardwood floors can be reused while carpet must be disposed of.
- Distinctions between types of wood and masonry also exist, often based on the time and place where they were produced (e.g. Saint Louis brick is more valuable than most other types, and old-growth timbers are more valuable than modern dimensional lumber).
- The only contractor currently conducting deconstructions in the region is a relatively new company and operates as a non-profit.
C&D waste diversion involves the recovery of recyclable materials from waste streams. Recyclable materials include metals (steel, iron, brass, copper, aluminum), aggregate (concrete, asphalt, brick, masonry), fiber (cardboard, paper), wood, shingles, and drywall.
Waste diversion is not as ideal as deconstruction, as significant energy is expended transporting and processing recycled and reused construction material. Typical diversion rates for projects seeking to recycle as much material as possible are between 70 and 75 percent and can reach as high as 90 percent.
What Other Cities Are Doing
Currently 128 local governments have mandates for diverting construction and demolition waste; all but ten of those are in California.
- Seattle enacted an ordinance in 2012 requiring the recycling of 100 percent of all asphalt, brick, and concrete, as well as the reuse of 20 percent and recycling of 50 percent of all remaining C&D material. As of 2013, 66 percent of Seattle’s C&D waste was being diverted from landfills — a number expected to surpass 70 percent by full implementation target date in 2015.
- Since 2006, the City of San Francisco has required that all C&D waste be sent to registered C&D disposal facilities, which are certified by the City to meet a minimum 65 percent diversion requirement. Waste haulers are prohibited from hauling C&D waste directly to landfills.
- The City of Portland began mandating 50 percent recycling of C&D waste in 1995. In 2008, this standard was increased to 75 percent. Additionally, since 2009, all solid waste, regardless of project size, must be processed by a registered recycler prior to being sent to traditional disposal facilities.
What Can Minneapolis Do?
Few municipalities have enacted ordinances mandating the reuse of building material from structures undergoing demolition, primarily due to the lack of market for used building material.
As the report stated, “Our region is no exception — currently there is only one contractor performing structural deconstruction in our region, and there are few used building material retailers. While mandating intensive deconstruction and material reuse would have the greatest environmental impact, due to market conditions, it is not feasible for Minneapolis to do so under present conditions.”
The report recommended this approach: “The City of Minneapolis should further explore the possibility of creating a program mandating a certain percentage of C&D waste be diverted from landfill disposal… Staff believes that the regional C&D market is well-developed and could accommodate a diversion requirement similar to those adopted by many other cities, if the City took a phased approach. Taking cues from Seattle’s phased implementation, Minneapolis could develop a system that includes a rising bar to help further develop the C&D recycling market, as well as educate both builders and contractors.”
In addition: “Staff believes that the best way for Minneapolis to reduce the environmental impact of demolition in the long term is to become a regional leader in deconstruction in an attempt to develop the local deconstruction market.
“Intensive deconstruction and the reuse of building materials have the greatest effect on reducing the environmental impacts of demolition. However, the local market for used building materials is not well-established or prepared for the widespread adoption of intensive deconstruction. There is currently a lack of contractors performing deconstruction, a lack of accurate data available for cost analysis, and a lack of professional appraisal staff to evaluate materials, and traditional builders have yet to take steps to systematically incorporate used building materials on a large scale. Until a cost analysis for Minneapolis, and the region, can be completed, it is unknown what other factors may impact the success of a deconstruction program.
“To better understand and collect data on the feasibility of deconstruction, it is staff’s recommendation to work with experienced local contractors to increase the number of City-owned properties to be deconstructed rather than demolished. The City has contracted Better Futures Minnesota to deconstruct several city-owned homes in the past, and should continue to work with Better Futures Minnesota. However, many City-owned properties have not qualified as candidates for deconstruction due to deterioration, structural issues, and lack of salvageable materials. Until programs are established, the City can encourage other contractors to develop deconstruction capabilities and assist with data collection.”
- Part 3: Where to donate or buy reclaimed building products
- Part 1: Green Building Standards in Minneapolis
- Q&A: Green architect Alex Haecker
- The full City of Minneapolis report can be found here.