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Grotto Sauna

Cosella-Dorken Products Inc.

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  • Building Enclosure/Artwork: Building Science Consulting, Inc.
  • Other: Jordan Construction

Project Status


Year Completed



800 sq. feet
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Project Description

Ambitious architecture in a remote and demanding environment
The Grotto Sauna near Parry Sound, Ontario, Can-ada, drew inspiration from the historical definition of a grotto – a secret water filled cave, concealed within unexpected rock formations. Perched on a private island in Lake Huron, the OAA Design Excellence Award nominated building is embedded in the ancient rock formation, the Canadian Shield, which forms the backbone of North America. The sculpted space compliments and becomes part of the prehistoric landmark.
Challenging the standards of current practices in the construction industry, every detail was communicated with a millwork and steel fabrication partner. Together, a new process of fabrication was developed, utilizing state of the art 3D technology to scan, model and build the Grotto, so that the building would sit naturally in the rock formation. To complement the surreal environment, PARTISANS decided on a simple, burnt Red Cedar exterior. In contrast, the curved White Cedar interior helps optimize air flow.
The Grotto requires two high performance ovens. Insulation was needed not only to protect its components from heating or cooling too quickly, but also to make the Grotto energy efficient. The space behind the wood panels creates convection currents that allow the skin to breathe through the ventilation pores that were carved into seats and seams of the cedar panels.
PARTISANS chose DELTA®-FASSADE S, a water- resistive barrier (WRB), to accommodate for the extreme temperature changes occurring inside and outside of the structure. Pouring water on the oven creates steam that makes the humidity with- in the structure jolt up in short, extreme bursts. DELTA®-FASSADE S has high vapor permeability, allowing for the moisture vapor that accumulates inside to escape. On the exterior, it acts as a durable drainage plane, channeling water from wind-driven rain and snow to the outside of the structure. The watertight membrane helps protect the building enclosure from damaging effects of moisture infiltration.
When PARTISANS met on site, they knew that their most prominent challenge was to make a freestanding structure that respected and complimented the environment. Understanding the rock formation was the first step in construction. After examination of the setting, it was determined that the best course of action was to prefabricate the building and deliver it to the site by barge and crane.
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