We are renovating large sections of exterior envelope at MDI High School, part of AOS 91 on Mount Desert Island. The project will be completed the summer of 2017

Design Challenge

The original portion of MDI High School dates back several decades, and is one of the many Alonzo Harriman-designed school buildings in Maine. The school underwent major renovations and additions in 2001. Portions of the renovated exterior walls have suffered from water intrusion since that time. While we could identify the cause of the water intrusion, Sealander Architects and the school took an opportunity to fix the envelope deficiencies by not only making the building more weathertight, but also more energy-efficient and with better interior lighting levels.

Solution

Our solution is to reclad the building with single-skin metal panels over spray foam insulation, and high-performance glazing. We effectively tripled the overall u-value of the exterior envelope.

Thermal System

The existing opaque walls were an assembly of wood clapboards, building paper, gypsum sheathing, metal studs with batt insulation, and gypsum board on the interior. Energy modeling of this assembly confirmed that the overall R-value was less than R-13. We added four inches of spray foam and a single skin metal panel sheathing fastened to metal framing girts. A stand-off gap between the new girts and existing gypsum sheathing provides a thermal break.