Rounded olivine diabase stones, 5–10 cm, sold in 33 lb boxes. They're shaped like the smooth stones you'd find in river rapids rather than the angular split-face stones most heaters use — and that shape changes how the steam behaves.

33 lbs of stones, each roughly 2" to 4" across.

Water runs off a rounded surface and travels down into the lower stone layers instead of flashing off the top. That means the water reaches far more stone surface area on its way through, producing more steam with a softer, gentler quality. Split-face stones give a sharper, more immediate burst; rounded stones give a rounder, longer one.

Neither — they produce genuinely different steam, and it's a preference. If you like a soft, enveloping löyly, rounded. If you like a sharp crack of heat, split-face. Some owners run a mix, which is covered below.

They're the specified stone for the Harvia Spirit series — the SP60E, SP80E and SP90E all call for R-991. They also suit other heaters where you want softer steam, but always check your heater's manual for the stone size it's designed around.

Depends entirely on your heater's stone capacity. The Spirit series takes 110 lbs, which is four boxes. A smaller heater might take one or two. Check your heater's specification, or ask us and we'll tell you exactly how many.

Check your heater's manual first. Most traditional electric and wood-fired heaters take 5–10 cm stones, but some specify larger 10–15 cm stones, and a few call specifically for angular rather than rounded. If you're not sure, tell us your heater model and we'll confirm.

Yes, and Harvia actually recommend it in one situation: on heaters with smaller stone capacity, use angular stones in the bottom layers because they hold more heat, then rounded stones on top for the steam quality. Best of both.

A dense volcanic rock that handles repeated heating and rapid cooling without splitting — which is exactly what a sauna does to stone every session. It's the standard material for quality sauna stones for that reason.

Because they can explode. Ordinary stone often holds trapped moisture or has a layered structure that fails when you pour water on it at 190°F. River rock and granite are particularly risky. Sauna stones are selected and tested for this specific abuse.

Yes — they're selected, cleaned and intended for sauna use, and they carry no Prop 65 warning.

Yes. Rinse them before loading to clear off dust from handling and transport. Otherwise the first few heats will smell of hot dust.

Loosely. This is the single most important thing — stack them so air can move freely between the stones, never wedged tight or forced in around the elements. Good circulation is what keeps the elements cool enough to last.

You choke the airflow. The elements run hotter than designed, the heater works harder to reach temperature, and element life drops significantly. It's the most common cause of premature heater failure and it's entirely avoidable.

Fill to the capacity in your heater's manual — no more, no less. Underfilling exposes elements and wastes steam potential; overfilling restricts airflow and can obstruct the heater's own safety sensors.

Larger stones at the bottom, smaller toward the top, is the general rule — it keeps the base stable and the airflow open. Your heater's manual is the authority if it specifies otherwise.

Once a year for a home sauna. More often for heavy or commercial use.

Look for cracking, crumbling, or stones that have visibly shrunk and settled. If the pile has compacted and airflow looks restricted, or you're finding grit at the bottom of the heater, it's time. Stones are consumable — they don't last forever.

Typically a year or two with regular home use, longer if you sauna occasionally, shorter in a commercial setting. Each heating cycle stresses them a little more.

Degraded stones restrict airflow, the heater runs hotter, and the elements fail early. Replacing $100 of stones is considerably cheaper than replacing a heater — this is genuinely the highest-return maintenance you can do.

Yes, once a year. Stones settle and compact over time even without breaking down. Taking them out, checking them and restacking loosely restores the airflow.

Yes, a rinse in plain water is fine and clears accumulated dust. Let them dry before reloading. Skip soaps and cleaning products entirely.

Yes — that's what they're for. Ladle plain water over the stones for löyly, one ladleful at a time. Never pour water directly onto the heating elements themselves.

Only sauna-specific products, diluted in the water bucket rather than poured neat onto the stones. Undiluted oils scorch, stain, leave residue that's difficult to remove, and in some cases can ignite.

No. Salt corrodes the heater, and sugary liquids like beer burn on and leave residue that smells for months. Plain water only — or a proper sauna fragrance in the bucket.

The first heat or two may have a faint mineral smell as any residual dust burns off. Rinsing them before loading minimises it, and it clears quickly.

No, and that's expected — these are natural stone, so every piece is unique in shape and size. Harvia suggest buying an extra box so you can select the best-fitting pieces for your heater and keep the rest as spares. Worth considering given the freight on stone.

It's not required, but it gives you choice on fit and a supply for topping up as stones settle. The trade-off is freight — stone is heavy, and shipping a spare box costs more than the box.

By parcel carrier, in 33 lb boxes. Freight is calculated to your address, and because stone is dense, shipping is a real cost rather than a rounding error. Ask us for a delivered price.

Sometimes, and we'd rather tell you than quietly sell you the freight. If a local sauna supplier stocks proper 5–10 cm sauna stone, buying locally can work out better on a large stone load. The catch is that R-991 rounded olivine specifically is harder to find than generic split-face — so if you want the softer steam these produce, they're worth ordering.

Yes, and it's usually the sensible way to do it — one quote, one delivery conversation, and we make sure the quantity actually matches your heater's capacity rather than leaving you to work it out.

Tell us your heater model before you order and it won't happen. Stone capacity varies enormously between heaters — the Spirit series needs 110 lbs, some compact heaters need 44 lbs, and larger commercial units need far more.

No. Sauna stones are a consumable, like brake pads or filters — they're expected to degrade with use and get replaced periodically. That's normal and not a defect.

Often yes, but wood stoves generally take larger stones than electric heaters. Check your stove's manual for the specified size — many call for 10–15 cm stones instead. Ask us if you're unsure.

No. Infrared saunas have no stones and no steam — they heat you directly rather than heating the air and a stone mass. If you have an infrared cabin, you don't need stones at all.

They're just rock — ordinary landscaping material once they've broken down. Drainage, path fill, or general disposal. Nothing hazardous about them.

Freight on stone varies significantly by address and quantity, and most buyers need these quoted alongside a heater. Request pricing and you'll get one delivered figure rather than a number you have to add shipping to.

We're an authorized Harvia dealer. Tell us your heater model and we'll confirm the right stone type and quantity before you spend anything — which matters more than it sounds, because the wrong size or a short order means a second freight charge on something heavy.

Please review our return policy at thesaunarepublic.com/policies/refund-policy. Given the weight and freight cost on stone, it's worth confirming quantity with us before ordering rather than after.

Call (302) 273-0861 or email info@thesaunarepublic.com and we'll be glad to help.