Best Outdoor Sauna Cover (2025)

Updated February 2025 — Backyard Sauna Pro

A barrel sauna sits outside year-round taking sun, rain, UV, freeze-thaw cycles, and snow load. The cedar holds up better than most woods, but UV exposure greys and cracks untreated wood faster than anything else. A quality cover extends your sauna's life and reduces how often you need to oil and retreat the exterior.

This guide covers what to look for, which options actually hold up, and when a cover matters most versus when it's overkill.

Do You Actually Need One?

It depends on your climate and how often you use the sauna. If you sauna multiple times a week year-round, the wood goes through regular heat-dry-cool cycles that keep it conditioned. The main threat then is UV when it's sitting unused.

If you use the sauna seasonally, say, April through October, and it sits unused through winter, that's when a cover pays off most. Prolonged exposure to freeze-thaw cycling with moisture-saturated wood accelerates checking and cracking on the stave ends.

In a mild climate with infrequent rain and moderate sun, annual oiling of the exterior handles most of the protection you need. In a wet, cold, or high-UV climate, a cover on top of oiling is worth it.

What to Look For

Fabric weight and waterproofing

The rating you want is at least 600 denier (600D) polyester with a UV-resistant outer coating and a waterproof PVC or polyurethane backing. Lighter fabrics work for light sun protection but fail within a season or two in rain and snow. Marine-grade canvas is the best material available but costs three to five times more, justified for a premium long-term installation, overkill for most buyers.

Fit

Barrel saunas come in varying diameters (typically 5 or 6 feet) and lengths (6 to 10 feet). A cover that's too loose bunches and collects water in pools that eventually leak through seams. A cover that's too tight risks tearing at stress points when wet fabric contracts. Look for covers sized by diameter and length with adjustable straps or drawcords at the base.

Ventilation

A completely sealed cover traps moisture against the wood, the opposite of what you want. Good covers have mesh vents at the ends that let air circulate while keeping rain out. If your cover doesn't have vents, leave the end panels slightly loose to prevent condensation buildup.

Securing system

Straps, buckles, or bungee drawcords that go under the sauna base keep the cover in place in high wind. A cover that blows off in a storm is useless. Check that the securing system can handle your local conditions before buying.

Top Picks

Alternative: Treat the Wood Instead of Covering It

Some sauna owners skip the cover entirely and rely on annual exterior treatment. This works, but requires commitment, if you miss a year, UV and moisture get a foothold fast on untreated cedar end grain.

If you go this route, use a clear penetrating oil formulated for outdoor cedar, not varnish, stain, or latex paint. Apply in the spring after the wood has dried from winter, and again in fall in wet climates. Pay extra attention to the barrel ends where the grain is exposed.

A cover plus annual oiling is the belt-and-suspenders approach for maximum longevity. For most people, one or the other is enough.

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