3D homes sound ingenious, but their time will probably never come
Well maybe not. The prospect of 3D printing of a house, ingenious as it sounds, is yet another in the long list of technological home-building ideas whose time has not come and probably never will come. It’s also an idea that carpenters and masons may not appreciate.
Home builders, practicing architects and engineers know that labor and materials for the structural frame — walls, floors, roof — of a house represent a small fraction of the total cost of a completed home ready for occupancy. Even if framing costs were cut in half, total building costs and selling price would be affected by an insignificant percentage, if at all.
This is not rocket science. Just think about everything needed beyond framing: windows and doors, insulation, plumbing and related fixtures, HVAC systems, cabinetry, appliances and finishes. Add to this the cost of the lot and its improvements: grading, foundation excavation, utility connections, landscaping.
On top of these costs are the home builder’s multiple indirect costs: regulatory processing and compliance related to rezoning and building permit issuance; legal fees; construction loan interest; insurance; advertising and marketing; and project management and administrative overhead.
The challenge for home builders is that an incremental cost saving in one component of direct house construction can be suddenly offset and made inconsequential by unanticipated increases in other cost components, both direct and indirect. This impairs financial feasibility, happens often and in fact is happening right now. Today previously planned projects and budgeted construction costs are rising rapidly because of price inflation, supply chain problems and increasing interest rates.
Clearly, all these real-world, interdependent costs associated with real estate development and construction impede home-building innovation. They are why demand exceeds housing supply in many areas of the country, driving up home prices. And they explain why producing affordable housing, whether for rent or sale, keeps getting harder, more expensive and more dependent on public subsidy.
Making matters worse are state and local growth and development policies — especially zoning — that constrain housing types, residential densities and intermixed land uses within urban, suburban and exurban areas. More-flexible regulations would reduce per-unit land costs for building housing.
These challenges are not new, just as technological exploration and invention are not new. There is a long history of efforts in the United States to study and address real estate and housing challenges, starting in the early 20th century. I participated in such an effort 54 years ago as co-author of a congressionally funded report titled “Roadblocks to Innovation in the Housing Industry.”
Our findings in 1968 have not changed. Like today, primary roadblocks then were rising direct and indirect construction costs; constrained availability and cost of mortgage financing, both for builders and for home buyers; and limited land availability with high land costs due to restrictive zoning regulations.
In the 1960s, prefabricated, factory-made housing was thought to be the technological innovation promising to save money and increase the supply of American homes. Plant assembly lines could manufacture homes at a very high rate. But factory production rates greatly exceeded rates at which finished homes could be shipped and inventoried, subdivisions created, improved lots prepared, mortgage loans obtained and sales closed. It was clear that innovation roadblocks were systemic rather than technological.
Only the mobile-home industry has successfully sustained volume production of reasonably affordable manufactured housing. But trailer-like homes deployed in exurban, dedicated mobile home parks cannot significantly address the country’s residential needs.
The roadblocks reported to Congress 54 years ago remain and are still non-technological. While possibly enabling cost-effective fabrication of some construction pieces and parts, 3D-printing technology is unlikely to do much to mitigate persistent, systemic housing challenges in the United States.
Roger K. Lewis is a retired practicing architect and a professor emeritus of architecture at the University of Maryland.
