Last Updated: October 15, 2025
When people in Ontario discuss building a home sauna, they usually picture the wood, the benches, maybe even the steam. But honestly, the roof is where a lot of things either go right or very wrong. After more than a decade working with roofing systems across Ontario, I’ve seen how a poor roof choice can ruin a perfectly good sauna setup, especially when humidity and winter moisture come into play.
A sauna roof needs to breathe, insulate, and protect. It’s not just a top cover; it’s part of the entire performance system. Regardless of whether you’re in Muskoka, Toronto, or Lake Simcoe, the roofing material you choose determines lot of things.
So, let’s talk about what really works in 2025. Let’s delve deeper into materials that not only look good but also perform exceptionally well.
1. Cedar Shingles – Still a Natural Favorite
Cedar shingles not only have unique aesthetics, they offer better moisture control inside your sauna, something critical if you’re battling high humidity or limited venting options.
Why it’s great:
- Naturally rot and insect-resistant
- Keeps the sauna temperature stable year-round
- Ages beautifully, turning a silvery tone over time
Just keep in mind, cedar roofs do need upkeep. In Ontario’s freeze-thaw cycles, regular inspection helps prevent warping or early wear. Book a professional roof inspection here if your sauna has been through a few tough winters already.
2. Metal Roofing – 2025’s Most Practical Trend
In recent years, metal roofing has become a go-to choice for modern sauna installations. It handles our winters like a champ and sheds snow fast. It also works well with energy-efficient sauna designs that rely on reflective insulation.
Modern metal roofs are now available in a variety of coatings and finishings, making it easier for homeowners to match them with the rest of their home’s aesthetics.
Why metal roofing works well in Ontario:
- Handles snow and ice buildup with ease
- Fire-resistant and low maintenance
- Works beautifully with barrel sauna shapes
For those considering a barrel-style sauna with a flat or curved top, you can even estimate your flat-roof costs here to plan your budget accurately before starting the project.
Tip: Several municipalities in Ontario require a minimum slope and specific fastening standards for metal roofs on small outbuildings. Always check the Ontario Building Codes or ask your installer to ensure compliance.
3. Asphalt Shingles – Simple, Reliable, and Cost-Effective
Not everyone needs a premium material. Asphalt shingles still do the job and have come a long way in both look and lifespan. For most backyard sauna projects in Ontario, especially where you want to match the home’s main roof, asphalt shingles are perfectly fine.
The key is choosing shingles rated for high humidity and freeze cycles. Some newer products are made with algae-resistant coatings, ideal for damp or shaded backyard setups.
Advantages:
- Affordable and easy to replace
- Flexible installation even on smaller roof pitches
- Comes in hundreds of colors and styles
Thinking of using asphalt? Make sure your roof deck ventilation is designed properly. Moisture from inside the sauna can shorten the lifespan of typical shingles if trapped under the surface.
4. Synthetic Roofing – The Smart Newcomer for 2025
Here’s where trends are changing fast. Often made from recycled rubber or polymer blends, synthetic composite shingles are gaining ground in Canada this year. They look just like cedar or slate but last longer and perform better in humidity.
Although they require a substantial amount, they are worthwhile investments because they hold their shape through years of heat and moisture exposure.
Key reasons people are switching:
- Maintenance-free and fully recyclable
- Resistant to mold, mildew, and rot
- Lightweight for small sauna structures
Suppliers like Enviroshake and Euroshield (both with Ontario distribution) are leading the charge in this trend. You’ll find their materials used in sustainable roofing projects across the province.
5. Slate and Clay – For Pure Aesthetic Impact
Slate and clay tiles are popular for their fire resistance and durability. However, they require reinforced framing because they are heavier. That said, if you want your sauna to also serve as an architectural feature, both are excellent options.
Nowadays, there are lighter synthetic versions of slate tiles available which offer similar looks at half the weight.
Worth noting:
- Clay and slate can handle high heat from nearby vents
- Lasts longer (50+ years) with minimal fading
- Ideal for custom-designed saunas or spa retreats
Why Your Sauna Roof Matters So Much in Ontario
Ontario winters are known for their unpredictability. You can be battling freezing rain this week and then facing a mild thaw the next. This kind of weather can be brutal for small outdoor structures like saunas. Roofing often takes the brunt of it, ice buildup, moisture from steam, and constant expansion and contraction from temperature swings.
That’s why I always tell homeowners, it’s not just about picking the right material. The way it’s installed and how well it’s vented make just as much difference in how long that sauna lasts. I’ve seen beautifully built cedar roofs rot out in a few short years simply because the vapor barrier wasn’t handled right. Once moisture starts seeping into the insulation or the wood frame, you’re looking at mold, soft spots, and eventually a full rebuild.
At NorthCan Roofing, we’ve worked on plenty of these sauna setups, from backyard spas to lakeside retreats, and moisture control is always the first thing we look at. The goal is to keep the inside heat and humidity where they belong, without letting it eat away at the structure over time.
My Take After Years of Working on Sauna Roofs
When it really comes down to it, picking a roof for your sauna isn’t just about how nice it looks sitting in the yard. It’s more about how well it holds up when Ontario throws one of its long winters or humid summers your way.
I’ve seen cedar age beautifully when it’s cared for right, and metal roofs that look just as strong after a decade as the day they were put in. The newer synthetic ones, I’ll admit, have surprised me too, they take a beating from the weather and just keep holding on. Every material has its own pros and cons. What you want is to find something that fits your setup and how you plan to use it.
Take your time before making a decision. If you feel uncertain about insulation, venting, and small maintenance checks, you can always give us a call. We’ve worked on a lot of these across Ontario, and we’re more than happy to walk through what’s worked best for our local clients, before you make that final call. Sometimes a quick chat can make all the difference between a sauna that lasts five years and one that lasts twenty.
Author Bio:
Alex is the founder of NorthCan Roofing, a trusted Ontario roofing company specializing in commercial and industrial flat roofing. With years of experience, Alex focuses on practical solutions that balance performance and design.