Barrel Sauna Foundation: Gravel, Pavers or Concrete Pad, Sizes and Depths

Not legal or electrical advice. This guide summarizes published manuals, codes and agency pages as of the date above. Rules change and vary by jurisdiction. Confirm your plans with a licensed electrician or contractor and your local building department before you buy or install.

Key facts

The base must be firm, level and able to carry the sauna and its users, "1,000+ lbs" (Almost Heaven manual).
Not on bare earth. If the sauna sits on the ground, the cradles should rest on paver stones or similar so they do not settle (Almost Heaven).
Almost Heaven's recommended depths: concrete pad 3 to 4 inches thick, or 4 to 6 inches of crushed stone.
Dundalk LeisureCraft: level, with a slight slope to the back for drainage. Minimum bases run 48 by 60 inches to 60 by 84 inches by barrel size.
Seattle and Portland both list a 12 inch frost depth (Seattle Residential Code Table R301.2; Portland structural design page).

The four base types, compared

Base	Maker guidance	Good for	Watch for in wet climates
Compacted crushed stone	Almost Heaven: 4 to 6 in of crushed stone. Listed by Dundalk and Redwood Outdoors.	Drainage, low cost, easy DIY	Cradles can settle into loose stone. Almost Heaven's fix for ground placement: pavers under the cradles.
Pavers or flagstone	Listed by Almost Heaven, Dundalk and Redwood Outdoors	Cradle-only bases, sloped yards	Set them on a compacted base so they stay level. Each cradle needs a continuous, level bearing.
Concrete pad	Almost Heaven: 3 to 4 in thick. Redwood Outdoors also lists concrete footings under each cradle.	Permanent installs, stays level for years	Pour with a slight fall so water does not pool under the drain stave.
Wood deck or platform	Listed by all three makers; must carry the full load	Existing decks, hillside lots	Weight and moisture. See can you put an outdoor sauna on a deck.

How big to make the pad

Dundalk LeisureCraft's 2021 cedar barrel manual gives minimum base sizes (width by length):

Barrel size	Minimum base
6 ft x 6 ft	48 x 60 in
6 ft x 7 ft	48 x 72 in
6 ft x 8 ft	48 x 84 in
7 ft x 6 ft	60 x 60 in
7 ft x 7 ft	60 x 72 in
7 ft x 8 ft	60 x 84 in

Add 24 inches of length for a porch and 48 inches for a changeroom. Dundalk also suggests building the base larger than the minimum so you have somewhere to sit and cool off. Its barrels under 10 ft long ship with 2 cradles, 10 to 12 ft with 3, and over 12 ft with 4.

Almost Heaven offers a second route: base only under the cradles. Its cradles measure 53 by 6 inches on 6 ft diameter barrels and 64 by 11 inches on 7 ft barrels. They sit 4 to 5 inches in from the ends of the staves, and any extra cradles are spaced evenly between.

How much material: worked examples

Our arithmetic, using the maker figures above. Not a quote.

Gravel pad for a 6 by 7 ft barrel. 48 by 72 in is 24 square feet. At 4 in deep: 8 cubic feet, about 0.30 cubic yards. At 6 in: 12 cubic feet, about 0.44 cubic yards. Order a little extra for compaction.
Concrete pad, same barrel with a porch. 48 by 96 in is 32 square feet. At 4 in thick: about 10.7 cubic feet, roughly 0.40 cubic yards, before waste.
Cradle-only pavers, 7 ft diameter Almost Heaven barrel with two cradles. Each cradle is 64 by 11 in, so a row of pavers at least 12 in wide and about 66 in long under each one, on a compacted stone bed.

Drainage, slope and Pacific Northwest rain

Slope it slightly, then shim. Dundalk asks for a slight slope to the back. Almost Heaven says a slight slope is fine but a pronounced one needs shims under the cradles, because an uneven base leads to staves that will not line up and a door that will not latch.
Keep wood off wet ground. Almost Heaven warns that erosion or soggy ground can throw a sauna out of level. Portland's outdoor projects brochure requires that deck posts and supports touching the ground or concrete be stamped for ground contact, a good standard for any wood platform under a sauna.
Frost depth. Seattle's code table lists a 12 inch frost line and a moderate weathering index, and R403.1.4.1 requires permanent supports of buildings to be protected from frost. Portland lists a 12 inch soil frost depth. A gravel or paver base is not a footing. If you pour footings for a cabin sauna or the city treats yours as a structure, start at 12 inches and confirm with the permit office.
Plan the wire before the pad. An electric heater needs a 240 V line, and Almost Heaven notes the electrician usually enters at the back behind the heater. Lay conduit before you pour or compact.

Before you build

Check whether your sauna needs a permit: Washington or Oregon and Portland. Portland's brochure says detached non-habitable accessory buildings of 200 square feet or less and 15 feet or lower need no building permit, but zoning still applies.
Use the base chart for your exact sauna. Sizes above are Dundalk's and Almost Heaven's, not universal.
Leave room to build. Almost Heaven says you need space for a person on each side during assembly, though only a few inches once it is built.
Pick the roof and wood with the base: see outdoor saunas in rainy climates and barrel sauna roofing.

Sources

Figures as published by each maker or agency and checked on October 23, 2026. The material quantities are our own arithmetic. Manuals change, so use the one that ships with your sauna. This guide does not replace the sauna manual, an engineer or your local permit office.

Related guides

Frequently asked questions

What is the best foundation for a barrel sauna?

The makers accept several. Almost Heaven lists a concrete slab, flagstone, a wooden platform, brick pavers and compressed gravel, and recommends a concrete pad 3 to 4 inches thick or 4 to 6 inches of crushed stone. Dundalk LeisureCraft lists a concrete pad, wooden deck, crushed gravel or patio stones and paver blocks. In a wet climate, the best choice is the one that stays level and drains: gravel with pavers under the cradles, or a slab with a slight fall.

How big does a barrel sauna foundation need to be?

Dundalk LeisureCraft's 2021 manual lists minimum bases from 48 by 60 inches for a 6 by 6 ft barrel to 60 by 84 inches for a 7 by 8 ft barrel, plus 24 inches of length for a porch and 48 inches for a changeroom. Almost Heaven says you can cover the whole footprint or only the cradles, which are 53 by 6 inches on its 6 ft diameter barrels and 64 by 11 inches on its 7 ft barrels.

Can I put a barrel sauna directly on the ground?

No. Almost Heaven says not on bare earth, because erosion or soggy ground can throw a level sauna off. Its manual says that if the sauna sits on the ground, the cradles should rest on paver stones or something similar so they do not settle.

Does a sauna foundation need to go below the frost line in Seattle or Portland?

Both cities list a 12 inch frost depth: the 2021 Seattle Residential Code Table R301.2 and Portland's structural design page. That depth governs footings for permanent structures that need them. A barrel sauna on a gravel pad or pavers is not a footing. If your sauna needs a building permit, or you pour footings for a larger cabin sauna, the 12 inch figure is the starting point, and the city has the final word.

How much gravel do I need for a barrel sauna pad?

Area times depth. A 48 by 72 inch pad (Dundalk's minimum for a 6 by 7 ft barrel) is 24 square feet. At 4 inches deep that is 8 cubic feet, about 0.30 cubic yards. At 6 inches it is 12 cubic feet, about 0.44 cubic yards. Order extra, because crushed stone compacts.

Should the sauna base be perfectly level?

Close to it. Almost Heaven says a slight slope is fine but a pronounced one needs shims, and that an uneven base can leave staves that will not line up or a door that will not latch. Dundalk asks for a level placement with a slight slope to the back for drainage.

Keep reading

Browse our saunas collection, see all guides, or ask us a question about your project.

What should a barrel sauna sit on? Gravel, pavers or a concrete pad, sized and built for rain