New Book ‘Hempsteads’ Features Code-Compliant Design Details for Hemp-Lime
A new book of architectural details for hemp-lime construction will be published in May, written by a pioneering US hempcrete builder who helped co-author the hemp-lime Appendix published for the first time in the 2024 International Residential Codes.
Asheville, NC-based Timothy Callahan’s long-awaited “Hempsteads: Architectural details for hemp-lime construction” includes code-compliant details and specifications from a career of hemp-lime and natural-building designs.
In the 2010s, before industrial hemp was even decriminalized in the 2018 Farm Bill, Callahan – then principal of Alembic Studios – designed and built about 10 hempcrete homes in North Carolina and Virginia – some of the earliest in the United States.
Hempsteads provides an overview of best practices for designing with hempcrete, including discussions of in-situ (hand packed) and spray-applied applications, structural requirements and lime binders. Callahan’s personal architectural details include designs for windows, doors, stud placement, wall bracing, electrical and plumbing rough-ins, roof and overhangs, foundations and application of lime plasters.
Callahan credited the winning design details with his experience “on both sides” as both a designer and a builder. “The designs are based on experience from successful projects that [builders] can use as a guide,” Callahan told HempBuild Mag.
“I have seen many people, especially in the natural building world, that have gotten into trouble,” he added. “They think, ‘oh, how hard can it be?’ But then it can lead to pretty significant failures, which can be very costly,” he added.
Hempsteads also includes the complete International Code Council’s 2024 IRC Appendix BL and commentary. The book has an option to purchase a download library of CAD-usable design details that can be utilized (with attribution) in new projects.
Well-received by US hemp building professionals
Already, others in the US hemp building industry are commenting on the book.
“Hempsteads is one of the most complete and useful texts on hempcrete construction,” wrote Cameron McIntosh, founder of Warren, PA-based Americhanvre Cast Hemp. Callahan has "truly dedicated his life to a more thoughtful approach to residential construction,” he added.
“Tim is a true professional,” said Ray Kaderli, president of New Braunfels-based Hemp Build Network. “Having this high-level engagement from some of the original pioneers in the space is of the utmost value. This book is a ‘must-have for the library of anyone building with hemp,” he added.
The book provides a "great overview of hemp lime construction with a great selection of architectural details, covering different framing systems for hemp building," wrote Tim White, natural building specialist and owner of Texas Healthy Homes.
High performance is unmatched
Back in the mid-2000s, Callahan said he and his colleague Clarke Snell, now based in New York, were inspired by the Architecture 2030 movement, which urged builders to design and build with materials that would have a less destructive impact on the environment.
The two were “ridiculously idealistic” and small enough that they decided “we’re gonna do this right now. We don’t have to wait [for 2030], let’s just give this a shot,” Callahan told HempBuild Mag. Snell and Callahan co-authored Building Green: A Complete How-To Guide to Alternative Building Methods in 2009.
But for Callahan, hemp-lime had high performance qualities that worked so well in the southeast United States, he soon found himself creating more and more projects insulated with hempcrete.
“The truth is for most people in our region, especially because of our climate, I just don't know anything that will perform the way that hempcrete does,” Callahan said. “If you use hempcrete on exterior walls, the odds of you having any mold issues, unless you just do something really egregious, are approaching zero. That’s a big deal for people’s health,” he added.
Callahan designed and built five houses in Asheville, including the iconic NauHaus prototype in 2009. Some of the homes were quite large and complicated.
Hempsteads: Architectural details for hemp-lime construction published by Haepenny, LLC, is available on Amazon.com and through HempBuild Magazine.