Pioneering The Original Aluminum Wood Burning Hot Tub

The AlumiTub was designed in 2001 to outperform traditional wooden hot tubs. This is where it came from, and why it is built the way it is.

It started with a tub that leaked

The original wood fired hot tub was prototyped in the backyard of a cabin on Thormanby Island, off the Sunshine Coast of British Columbia, where the tub had always been the centerpiece of time spent there. It drew people in every morning and every night, and brought family, friends and neighbors together.

It also leaked, because all-wood tubs eventually do. A tub built from staves relies on the wood swelling to seal itself. Leave it empty and the wood contracts. Refill it and you start the process again. At a remote property, where every fill has to be hauled or pumped and nobody is there for months at a time, that is not a small annoyance.

So the goal was narrow and specific: design a wood fired hot tub that would never leak.

The answer came from aluminum, and from an aerospace engineering background where the material is understood well. A welded, pressure-tested marine-grade aluminum vessel holds water because of how it is made, not because of how wet it is. That single decision solved the leak, and then kept solving other things.

What the aluminum made possible

Once the vessel no longer depended on wood movement, a series of things followed that an all-wood tub cannot do.

It could be drained and left empty. No re-swelling in spring, no leaking on the first refill, no keeping it full through a winter nobody is there for.

It could be insulated on all sides. Wrapping a stave tub in insulation traps moisture against the wood and rots it. Aluminum does not absorb moisture, so the tub could carry 360 degrees of insulation: the sides, the base and the water surface beneath the lid.

It could be filled from the ocean. Marine-grade aluminum is specified for salt water, so at a property with limited fresh water, the sea in front of the cabin became the supply. Ocean fills are changed every five to seven days rather than left standing, and the tub is rinsed between fills. More in saltwater against freshwater.

It could be moved. Pre-assembled, 200 to 300 lbs empty depending on size, and 38 inches on its side so two people can roll it through a gate or onto a truck bed between the wheel wells. No crane, no groundworks, no contractor.

That was over twenty-five years ago. There are more aluminum wood fired hot tubs on the market now, which is its own kind of compliment. Thousands of AlumiTubs are in use on properties across North America and beyond.

The firebox

The firebox sits inside the tub, below the waterline, heating the water directly rather than circulating it through an external stove and a plumbing loop.

Direct transfer is more efficient, so less wood does more work. There is no external heat source to trip over or touch, and the portion under water stays at water temperature. A cedar fence keeps bathers away from the stove body and chimney, which are the parts that do get hot.

It is the largest of its kind, which means it takes regular full-length logs with no cutting to size, and it draws well enough to burn cleanly once established. From cold, that gives roughly two hours on the Small, three on the Standard and about five on the Large. The art of heating a wood fired hot tub covers how to run it, and the best firewood to use covers what to burn.

One instruction matters more than the rest: never light the fire before the tub is filled. Fill to the line marked on the tub, or at least 4 inches above the chimney collar, and keep the water there the whole time the firebox is hot.

Every firebox is cut and welded in the shop on the Sunshine Coast.

Round, and why

There is a real difference between a round tub and one shaped like a bath.

A round tub rolls into place rather than being lifted, which is what makes delivery and repositioning possible without machinery. And it is a place to gather rather than lie down, so nobody is playing footsies with the person at the other end. A rectangular tub is, functionally, a shared bath.

All three sizes share the same internal depth of 38 inches, so the tallest person in the group is not the one left cold. The Small seats 2 to 3, the Standard 4 to 5 and the Large 6 to 8 on a Wood Fired or Hybrid. An Electric seats more per size, 3 to 4, 5 to 7 and 9 to 10, because there is no firebox inside. What size cedar hot tub do you actually need works through the choice.

Cedar on the outside

Canadian Western Red Cedar forms the seating, the protective firebox fence, the lid and the exterior cladding. It is sourced locally, from within the community, and it does real work rather than decorative work: cedar is naturally insulating, naturally rot-resistant, and it ages into a silver-gray patina rather than degrading.

It also carries a scent that is inseparable from the experience. More in why AlumiTubs use Canadian Western Red Cedar and how we source our materials.

Insulation, and what it actually buys

The tub carries 360 degrees of insulation: 3.5 inches of rigid board beneath the base, a full wrap around the drum, and a floating layer across the water surface under the cedar lid. Reflective insulation sits between the cedar and the aluminum structure.

In practice that means overnight loss of roughly two to three degrees Fahrenheit with the lid in place on a wood fired tub, and an armful of wood a day to hold soaking temperature once it is up. On an Electric there is no overnight drop, since the system holds the temperature you set and the insulation means the heater rarely cycles. On the wood side, AlumiTubs have been tested heating in ambient conditions as cold as minus forty-four degrees Celsius. Cold weather testing covers what that looks like through a winter.

An optional stainless steel bottom band conceals the insulation neatly beneath the tub.

Easier to clean, and easier to drain

A smooth, non-porous aluminum interior wipes clean with a soft cloth and a mild plant-based cleanser. Never abrasive, and never vinegar. The cedar components are accessible on all sides and take a soft brush.

Water care is simple, and the ranges are the same across every model: alkalinity 80 to 120 ppm adjusted first, pH 7.4 to 7.8, calcium hardness 150 to 250 ppm, then bromine at 2 to 3 ppm. Never chlorine, and never a salt chlorine generator. Good Clean Living Water Care is built around those ranges and around aluminum.

The drain kit directs water where you want it: to a convenient point, back to the lake or ocean it came from, or into the garden. It needs a channel formed in the insulation base, so it is worth planning at the same time as the site. Never drain below the fill line until the firebox has fully cooled.

Where it went next

The original problem was a leaking tub at a remote cabin. The range now covers properties that look nothing like that one.

A Wood Fired can be built with compatibility ports so electric heating and filtration can be added later. The Hybrid carries both systems in the same tub, run alone or together, which keeps it in service through a fire ban when the firebox cannot be lit. The Electric holds a set temperature between 50 and 104°F with timer schedules for heating and filtration, a single 30 gpm jet that keeps it close to silent, a 50 micron filter that holds a fill for three to four months, and the whole system concealed in cedar steps where every part stays reachable. The complete guide to heating options compares all three.

What has not changed is where they are made. Nothing is imported or outsourced. Each tub is built by hand on the Sunshine Coast, water tested before it leaves the shop, and backed by a 25 year structural warranty.

We have happily been using our AlumiTub for nearly 20 years. Thank you for building such a remarkable product. I can't tell you about the countless happy hours we have spent in its warm confines.

Heidi and Bruce Reugg

The short version

• An internally submerged firebox, the largest of its kind, cut and welded in-house, heating the water directly
• 360 degrees of insulation: rigid board at the base, a full wrap around the tub, and a floating layer on the water surface
• On wood, overnight loss of two to three degrees Fahrenheit with the lid on, and an armful of wood a day to hold temperature
• Wood fired heating tested in ambient conditions as cold as minus forty-four degrees Celsius
• A welded, pressure-tested marine-grade aluminum structure that does not depend on wood swelling to seal
• Compatible with fresh, lake, river and ocean water
• Pre-assembled and rollable, with no electrical or plumbing installation required on the Wood Fired
• Wood, electric or both, and changeable later rather than replaced
• Custom drainage to wherever suits the property
• A submerged firebox that is not hot to touch under water, behind a protective cedar fence

For everything in one place, read the Ultimate Guide to Wood Fired Hot Tubs.