knowledge-kitchen / domestic-construction

Russian Banya

Thursday, 13 March 2025.

Research into the construction of a Russian banya (or Finnish sauna) - a necessity for any home. Construction began 2 December 2024 and was completed about 2 months later.

Model

Initial banya plans. Note that these plans were modified during construction, as new reliable resources were found contradicting some of the initial research.

Foundation

There are two types of above-ground structural foundations: pier or skid

• pier involves vertical posts upon which the foundation rests.
• skid involves laying a foundation directly on the ground
• in either case, make sure string outline is square by measuring diagonally from corners

Pier foundation

• lay out outline of walls w/ string
• mark out every 4 feet along string
• dig 12” below frost line (check village inspector about depth of frost line)
• bury treated 6x6 posts or sona tubes (tubes filled w/ concrete)
• attach/set anchor bolt in center of each post
• attach 6x6 post to anchor

Skid foundation

• simplest type
• no digging necessary
• consists of treated 4x4 or 6x6 lumber
• lay out lumber the length of cabin
• space out according to standard
• floor joist spans dependent upon lumber type
• consider deck blocks with floor posts inserted into them underneath floor joists
• see http://www.finehomebuilding.com/2003/04/01/a-firm-foundation-for-a-backyard-shed

Size

• no taller than 7’, otherwise lower areas do not retain heat as it rises [note this height restriction commonly mentioned in American sources was later found to be totally and utterly wrong, and plans were adjusted to be 8.5’ tall]
• 8’x10’ fits 7-10 people
• 5’x7’ and 6’x7’ popular for home, fits 3-5 people
• inside dimensions should be multiples of 12” for standard tongue and groove interior boards

Floor

• doesn’t need insulation
• plywood subfloor paint or waterproof sealant
• durarock covered in a coat of vinyl cement repair, or simple cement tile, cement, tile, or something that won’t absorb water on top
• duckboard floors are often placed on top
  • removable sections of 1”x3” or 1”x4” wooden slats with 1/2” spacing between the slats
• cut shower drain in center, ideally sloping floor towards drain
• can use vinyl cement patch 40lb and trowel it onto subfloor 3/4” around perimeter, sloped to 1/4” at drain

Framing

• frame with 60”x84” space between wall studs

Wall framing

• 2”x4”s for headers and plates
• 2”x4”s for framing studs
• make sure your spacing of studs works for whatever sheathing material you are using
• place load-bearing wall studs 16” apart and non-load-bearing studs 24” apart
• start by marking the bottom and top plates every 16” (except first and last marks, which are 15.25” from nearest mark)
• note that the so-called 2”x4” is actually 1 1/2” by 3 1/2”
• add horizontal supports between studs at height where benches can be screwed in
• secure all frame joints with two 3 1/2” nails

Roof framing

• run roof rafters longer than needed
• cut “birds mouth” slots into rafters where they sit on top of wall top plates
• can bolt rafters to walls with hurricane ties
• stove pipe thimble can insulate and space the stovepipe where it goes through the roof

Windows

• use only single glazed tempered glass, not double-glazed because they fog up

Door

• opens outwards
• standard = 24” x 72”
• rough opening = 26” x 75” (1/2” more on each side than actual door size for wiggle room)
• headings are 1” wider than door on both sides, plus another 3” extra total
• handle made of wood
• non-metallic door catch available from sauna dealers
• leave air space below door of 5/8” to 1” for oxygen

Vents

• intake vent below heater near floor
• exhaust vent towards the ceiling on other side of room
• perhaps a second exhaust under the benches
• 3”x10” duct space

Insulation

• high-temp aluminum foil vapor barrier with shiny side in (Type C single-side foil)
  • start from bottom of wall and work up so higher sheets overlap lower ones
  • use aluminum duct tape to cover seams and tears`
• conventional fiberglass insulation batts (usually come in 15” widths for standard stud openings)
  • R13 for walls
  • R22 or R26 for ceiling
• can put two layers of R13 laid in perpendicular orientation`
• consider recycled cotton insulation rather than fiberglass, because it’s easy to work with and non-toxic (brand name UltraTouch by Bonded Logic)
• floor doesn’t need insulation
• caulk bottom of walls meeting floor

Interior

Wood and nails

• deciduous trees
• western red cedar, aspen, spruce, hemlock, pine?
• some varieties may leak melting sap which can hurt
• tongue and groove boards of 1”x4” or 1”x5” nominal widths
  • with the grooves facing down so water can’t collect into them
• galvanized 1.5” nails
• 5D galvanized small head siding nails

Heater

• drum stoves are popular because doesn’t require welding.
• preferable to feed wood from predbannik, although more complicated to run stove through wall
• volcanic rocks placed on top of heater to retain heat
• wire mesh to hold rocks in place

Benches

• use thick 2”x2” or 2”x3” or 2”x4” planks
• avoid knots in wood since these heat up more
• fastened w/ screws on underside
• two-tiers
• L-shape?
• long enough to stretch out
• generally allow two feet of bench for each person on the upper bench
• 1/2” gap between planks
• lower bench should be 18” from floor and 17” deep for strength
• upper bench should be 18” higher than lower bench, about 3 1/2
• 4 ft from ceiling and 20” to 35” wide for comfort

Lighting

• lighting should be discrete and not cast shadows
• 60W light bulb, weatherproof and heat proof encasement
• or follow Finnish tradition with a candle window between the predbannik and the banya

References

• Trumpkin’s notes on building a sauna
• http://www.saunatimes.com/category/building-a-sauna/
• http://www.saunatimes.com/category/building-a-sauna/stoves/page/2/
• http://homesaunakits-since1974.com/Sauna-Building-Aids/106-sauna-building-how-to-build-a-sauna.html#1-buy-a-sauna-kit-to-do-it-yourself
• framing tips: https://www.mycarpentry.com/framing-carpentry.html
• https://web.archive.org/web/20060126211339/http://cankar.org:80/sauna/building/design.html
• tour of 8x8 sauna: https://www.youtube.com/watch?v=56nP5u3FAbI&t=333s
• tudor shed plans: https://www.buildeazy.com/plan_links_sheds.html
• pretty shed: http://www.livingroofsinc.com/wp-content/gallery/s-h-e-l-t-e-r/p4190156-copy.jpg
• stove clearances: https://cdn.shopify.com/s/files/1/1661/5331/files/nippaInstallManual.pdf?3150570655419202463
• cross-section of shed design: http://shedplanspackage.com/wp-content/uploads/2013/11/work-shed-designs-2.jpg
• nice overview of building features: http://bouldersauna.com/
• kit company with useful layouts: http://www.finlandiasauna.com/pdf/Finlandia_Sauna_Brochure-WEB.pdf