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12 decisions to work through before you build. Most people get 3 or 4 of these wrong and end up with a sauna that's too slow to heat, damp, or just uncomfortable.
This checklist covers all of them — with the right numbers, not vague advice.
Structural, insulation, and drainage requirements differ significantly. This decision drives everything else.
Cubic footage alone isn't enough. You need adjustment factors for glass doors, exterior walls, and stone mass.
Most DIY saunas get this wrong. Bad ventilation means stale air, slow heat recovery, and a sauna that feels damp.
Walls need R-13 minimum, ceilings R-19+. Under-insulating is the most expensive mistake to fix after the build.
Aluminum foil vapor barrier on the warm side of insulation. Get this wrong and you get mold inside your walls.
Upper bench 40–48 inches below the ceiling. Lower bench 18 inches off the floor. These numbers aren't arbitrary.
Cedar, alder, and basswood are the standards. Each has trade-offs on cost, durability, and heat retention.
No locks. Windows are optional but if you add them, they need to be the right type for the heat environment.
Concrete, tile, or duckboard — each works differently for water management and heat.
Most electric heaters need 240V / 40–60A dedicated circuit. Don't DIY this part.
Size, electrical work, and proximity to property lines all matter. Common patterns across most areas.
Igneous rocks only. Sedimentary rocks absorb water and can explode under heat. Not a place to cut corners.
Built from the same specs we use in our paid design work. Free — no catch.
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The Sauna Design Toolkit goes deeper on every one of these decisions — sizing calculators, ventilation diagrams, materials lists, and a complete build sequence.
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It's a list of the 12 most important decisions you need to make before building a sauna — heater sizing, ventilation placement, insulation values, bench heights, vapor barrier material, and more. Getting even a few of these wrong leads to a sauna that heats slowly, feels damp, or costs significantly more to fix later.
Anyone planning to build a sauna — whether you're a homeowner doing it yourself, a homeowner hiring a contractor, or a contractor adding saunas to your services. The checklist covers the design decisions that determine performance regardless of who swings the hammer.
Most online guides give vague advice like 'make sure you have good ventilation.' This checklist gives you the actual numbers and specs — R-values, bench heights in inches, heater sizing formulas with adjustment factors. It's built from the same specs we use in our paid design work.
You'll get the checklist delivered to your inbox right away. Over the next few weeks, we'll also send a short series of emails that go deeper on the most critical items — insulation, bench design, and ventilation — with examples from real builds.
Especially if you're hiring a contractor. Most general contractors haven't built a sauna before. This checklist helps you ask the right questions and catch mistakes before they're built into your walls.