In a fortuitous set of circumstances, two families approached Hyperlocal Workshop at around the same time with similar needs. Each wanted a small cabin on land they owned in the mountains of Colorado, one at 7,000 feet elevation and one at 9,000 feet for a place to commune with nature with their young children. They both agreed that we could develop the same building system for each of them so we could focus on getting the most design out of the diminutive spaces. These tandem requests inspired the CABIN_ph project, a series of simple Passive House mass timber modular retreats to explore flexible housing.

The design concept is rooted in a simple shed roof structure that can host a loft, separate sleeping area, bath, and kitchen and dining space. The two relatively remote locations led us to decide early in the process to make the structure modular, using 3’6” by 8’0” sections of nail-laminated timber (NLT) panels for the walls. Traditionally, an NLT building system was used in many larger buildings a century ago but has been largely forgotten in modern construction. As a renewable and affordable mass timber system, it eliminates additional finishes and can be used in multiple horizontal and vertical structural applications with only about 30% more wood resources compared to conventional framing. It also is easily fabricated in a small shop with minimal tooling.

The NLT panels we are using are built off site by First Haus Co in Taos, New Mexico, using common 2x4 framing lumber and the LignoLoc timber nail, which provides the mechanical fastening but still allows for the panels to be cut. Similar to dowel laminated timber (DLT) the system avoids the glues and extensive processing of cross laminated timber (CLT). On the exterior side the wall panels are sheathed in plywood and wrapped with an Intello membrane for vapor control and airtightness. The outboard insulation layer is a full-height Larson Truss system filled with 16 inches of wood fiber insulation. Further structural testing would be valuable to reduce or eliminate the need for plywood.

The panels come in two types; one is opaque, and the other hosts a window or door. Stacked panels provide a roof pitch that allows for a code-approved set of stairs to the loft. The panels can be placed in any linear configuration to the site to adapt for views, egress, and solar gain. This approach allows the floor plans to stretch from 450 square feet to more than 1,000 square feet with no additional structural development required.