Sauna foundation and site

Makers want an outdoor sauna on firm, level, well-drained ground: a concrete pad, compacted gravel, pavers or a reinforced deck, never bare earth. Most of the published detail comes from Almost Heaven, and it is attributed here.

Choosing the spot

Almost Heaven lists flat, level ground and good drainage as the first factors in choosing an outdoor sauna location. Almost Heaven's rule for placing an outdoor barrel sauna is firm and flat, with a slight taper for run-off acceptable. (Almost Heaven Saunas; Almost Heaven Saunas)

Almost Heaven says a finished barrel needs only a few inches of clearance, but during construction there should be room for a person on each side. (Almost Heaven Saunas)

Finnish Sauna Builders says most areas require permits for structures like saunas and advises checking local building codes.

The bases makers accept

Almost Heaven names concrete slab, flagstone, a wooden platform, brick pavers and compressed gravel as the most popular barrel sauna bases. (Almost Heaven Saunas)

Almost Heaven recommends a concrete pad for larger or permanent outdoor saunas, at an ideal thickness of 3-4 inches with proper leveling. Finnish Sauna Builders says a concrete slab must be thick enough to bear the sauna's weight, typically around 4-6 inches. (Almost Heaven Saunas)

For a gravel base, Almost Heaven says to use crushed stone or gravel at least 4-6 inches deep, compacted into a firm, level base. Finnish Sauna Builders says concrete pavers are set on a bed of compacted gravel and sand and suit sites where a permanent foundation is not wanted. (Almost Heaven Saunas)

Almost Heaven says a deck used as a sauna base must support the sauna's weight and have ventilation underneath to prevent moisture buildup. Finnish Sauna Builders says a wooden deck used as a base must be treated for outdoor use and reinforced for the sauna's weight. (Almost Heaven Saunas)

Finnish Sauna Builders says to excavate the top layer of soil at least 6 inches deep to remove grass, roots and loose soil before building an outdoor sauna base.

Barrel saunas specifically

Almost Heaven says a barrel sauna should not sit on bare earth, because erosion or soggy ground can throw a level sauna off over time. Almost Heaven warns that a site that is not level can make barrel staves hard or impossible to line up, or stop the door latching properly. (Almost Heaven Saunas)

Almost Heaven says an outdoor barrel's base can cover either the whole footprint or just the cradles that support the sauna. Almost Heaven gives its barrel cradles as 53" W x 6" D for 6-foot-diameter barrels and 64" W x 11" D for 7-foot-diameter barrels. (Almost Heaven Saunas)