Cornerspring
Montessori
Middle School Building Annex
Case Study · Institutional / Educational · CLT Prefab · High-Performance
A High-performance CLT school assembled in two days
Cornerspring Montessori School had a clear goal: extend Montessori education to middle school-age students in the midcoast Maine community. What they needed was a building that could match that ambition — high-performance, sustainable, and completed without disrupting the existing school campus.
The result is a freestanding 1,000-square-foot building fabricated offsite at the NotchSB facility in Madison, Maine and assembled on Cornerspring's 35-acre Belfast campus in just 2 days. Structural panels arrived by truck and were craned into place by NotchSB's in-house installation crew — a construction timeline that would be impossible with conventional stick-frame methods.
Project Data
| Client | Cornerspring Montessori School, Belfast, Maine |
| Location | Belfast, Maine |
| Design Team | OPAL Architecture |
| Builder | NotchSB |
| Year | 2021 |
| Size | 1,000 square feet |
| Program | Two classrooms, shared entry, coatroom, and bathroom |
| Energy Standard | Passive House-level performance |
| Structure | Cross-laminated timber (CLT) prefabricated panels |
| Insulation |
Wood fiber — TimberBatt and TimberBoard Roof: [value] Wall: [value] |
| Fabrication | Offsite at NotchSB Madison, ME facility |
| Installation | Two-day onsite assembly, crane + in-house crew |
| Monitoring | 50+ building envelope sensors — UMaine partnership |
The NotchSB prefab panel system: structure, insulation, and finish in one assembly
The building employs the NotchSB all-wood prefabricated panel system — a construction approach that combines cross-laminated timber and wood fiber insulation in a single integrated assembly. Each panel provides structure, thermal insulation, and interior finish simultaneously, eliminating the layered coordination complexity of conventional construction.
Wood fiber insulation — TimberBatt and TimberBoard from TimberHP — delivers high thermal performance and vapor management alongside the CLT structure. The result is a building envelope that outperforms stick-frame construction on airtightness, thermal bridging, and embodied carbon, while reducing total on-site construction time, site disturbance, and project carbon footprint.
Panel System
CLT structure + wood fiber insulation combined in prefabricated all-wood panels. Each panel delivers structure, thermal envelope, and interior finish in a single integrated assembly — eliminating the layered coordination of conventional construction.
Carbon Advantage
Mass timber sequesters biogenic carbon. Wood fiber insulation adds further embodied carbon savings. Together they produce a building envelope with a significantly lower carbon footprint than steel or concrete alternatives.
