On a small island in Muskoka Lakes, Ontario, Canada, PARTISANS transformed a former ice-storage hut into the Muskoka Island Spa. At just 525 square feet, the compact building retains much of its original character on the outside, while its interior introduces carved Canadian Shield granite, custom-milled cedar and a sequence of sauna, cold plunge, steam and massage spaces.
The result is a spa that feels surprisingly different from the modest cabin visitors encounter on arrival. Its materials draw directly from the northern Ontario landscape, while the building’s original structure remains visible throughout the transformation.
The little green cabin still looks much like an ice hut
From the outside, the spa maintains the simple appearance of its former life. Dark green cladding covers the walls, while the pitched roof and scattered yellow-trimmed windows retain the quirky character of the original cabin.
The building sits beneath the trees, alongside exposed rock and the island’s footpaths. A heavy timber door, originally part of the ice-storage hut, remains in place, giving the entrance a substantial presence.
Before visitors even enter, an outdoor stone shower introduces the spa experience. Crossing through the old timber door then begins a sequence that moves from the island landscape into cedar, stone, heat, cold water and steam.
Inside, the tiny footprint packs in four thermal spaces
The compact plan contains a sauna, cold plunge, shower-steam room and massage room, with additional amenities tucked into the edges of the cabin.
Because the spaces sit close together, moving from one area to another creates noticeable changes in temperature and material. Heat gives way to cold water, followed by steam and spaces for sitting or resting.
The original 525-square-foot footprint also presented a major design challenge. With no conventional road access to the island, transporting and assembling everything required considerable precision, leaving little room for adjustments once materials arrived on site.
Granite rises from the floor like exposed bedrock
One of the most unusual features of the spa is the way Canadian Shield granite moves through the interior.
Large-format granite covers the floor, with pale seams and swirling striations recalling the bedrock surrounding the cabin. In the bathing and sauna areas, the stone appears to rise from the floor, becoming basins, thresholds, seating and sculpted edges.
The cold plunge is carved from the same geological family of granite found around the site, bringing the island’s geology directly into the spa.
The stone also wraps around the sauna heater, while curved granite elements create places to sit, lean and descend into the water.
Cedar bends around the granite
The cool, heavy character of the granite is balanced by custom-milled cedar covering the walls and ceilings.
Instead of remaining as simple flat boards, the cedar shifts into projecting ribs, curved planes, softened corners and built-in elements. Inside the sauna, it becomes benches, backrests, apertures and enclosure.
This creates a clear contrast between the two primary materials. The granite is dense and geological, while the cedar introduces warmth through its continuous vertical grain.
Together, they make the interior feel less like a conventional cabin and more like a space carved directly into stone and timber.
Machining the granite became part of the design challenge
Working with the Canadian Shield granite was far from straightforward. Its extreme hardness wore down the tools used during fabrication, making the material’s physical resistance an important part of the construction process.
The curved timber and stone elements, including the cold plunge, sauna benches and steam room seating, were developed with the fabricator as interconnected pieces.
Digital milling and hand-finishing allowed the granite and cedar to meet across curved surfaces and sculpted forms. Because the island offered limited opportunities for on-site adjustment, these elements had to be resolved with considerable precision before installation.
The old gable remains overhead
Despite the highly sculptural interior, the original ice hut never completely disappears.
The retained gabled volume and exposed roof structure remain visible overhead, providing a reminder of the building’s earlier purpose. The modest windows and heavy timber door also survive, while the outdoor stone shower reinforces the relationship between the cabin and the landscape outside.
There is an interesting contrast between the simplicity of the original structure and the complexity introduced within it. What was once a small building for preserving ice is now organized around movement between heat, cold water, steam and massage.
The transformation gives the old hut an entirely new function without losing the architectural clues that reveal where it came from.
A tiny spa shaped by an island’s geology
The Muskoka Island Spa began as part of a wider rethink of the island’s architecture, with the existing ice-storage hut offering an opportunity for a compact spa with a strong connection to its location.
The limited footprint encouraged an unusually integrated approach. Stonework, cedar, bathing elements, cabinetry and mechanical systems were developed together within a digital model, allowing the various components to fit into the cabin’s tight dimensions.
References to eroded rock formations, slot canyons, traditional landscape painting and sculpted timber interiors informed the design. The result is a small building where the character of the island is present not only through the views outside, but through the granite beneath visitors’ feet and the cedar wrapping the interior.
From its dark green exterior to its carved cold plunge, the Muskoka Island Spa manages to preserve the humble identity of an old ice hut while giving its interior a completely unexpected new character.