How to build an outdoor sauna

Written by contributing writer
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Outdoor saunas are convenient and you know, or at least have a pretty good idea, who was in them last. They are relatively easy to build, if you keep your design simple.

It is necessary to provide a sturdy foundation for an outdoor sauna to sit on. For the purpose of this article, we will assume that you have already poured or built some sort of foundation for the outdoor sauna.

Skill level:

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Things you need

  • Plans, sketches, or blueprints
  • Birch or oak wood for the flooring, outside walls, and roof; cedar wood for the inside walls. (See TIPS for more information).
  • Power or hand saw
  • Hammer or electric nail gun and nails
  • Insulation

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  1. 1

    Decide how you want your sauna to look, and how big you want it to be. (See TIPS for more information.)

  2. 2

    Keeping in mind that the average size of a piece of lumber board (for the walls) is two feet by four feet, with a length of eight feet, and plank board (for the flooring) is eighteen inches in width by ninety-six inches in length, with a two-inch thickness, according to your plans, determine how much wood you will need. Purchase the wood and other things you need.

  3. 3

    If necessary, cut the wood and planks to the lengths and widths you will need, based on your plans.

  4. 4

    Following your plans, build your floor first. Nail four pieces of two by four birch or oak lumber together to form the frame, and then nail additional pieces of two by four birch or oak lumber at evenly spaced intervals to form the supports. Nail down the required number of birch or oak plank boards that you will need to form the floor surface itself.

  5. 5

    Build your wall and roof FRAMES in the same manner as you built the floor, using the birch or oak lumber (refer to Step 4).

  6. 6

    Using the birch or oak planks, build the OUTER walls, and then attach them to the floor.

  7. 7

    Place insulation between the spaces formed by the lumber that was used to build the wall frame and supports.

  8. 8

    Nail the CEDAR planking over the insulation, using the wall frames and supports to hold the nails.

  9. 9

    Finish your roof, if you have not already done so, and then attach it to the structure.

  10. 10

    Build simple bench seats (you can use cedar wood on them, also) and attach them to the walls.

  11. 11

    Install your sauna heater (that you ordered and have provided a power source for), fire it up, and enjoy your outdoor sauna!

Tips and warnings

  • You can download plans and sketches of saunas, or you can buy books that will give you plans and sketches of saunas. Or, if you pretty much know what you want, you can hand-draw your plans or use a computer-aided drafting or blueprint program to design your own plans.
  • Bear in mind that the more dimensional you make your walls (for instance, eight feet high by eight feet wide), the less wood you will have to cut.
  • Birch or oak wood is best for actually building the sauna itself, as cedar, although a hardwood, will not last as long as birch or oak. You can, however, use cedar on the inside of the sauna. Simply buy cedar planking that is thinner than that used for the outside walls, floor, and roof.
  • You may wish to build all four outside walls first, and then attach them (one at a time, of course) to the floor. Your work will go more smoothly, as you will not be building then attaching, then building and attaching again until you have finished the walls.
  • You may want to consider water-sealing your wood, but leaving it natural beyond that. Wood that weathers on its own is usually as beautiful, if not more beautiful, as painted or stained wood. This is, however, your choice.
  • Check with a doctor if you have any pre-existing medical conditions before using an outdoor sauna. Using an outdoor sauna will actually make some medical problems worse.
  • DO NOT allow yourself to become overheated when using the outdoor sauna. And, drink plenty of water before, during, and after you use the sauna.
  • Do not go from one temperature extreme to another too quickly. Allow yourself time to cool down a little before you leave the sauna, especially if it is very cold outside.
  • Feel the surfaces first, before sitting down or leaning back in the sauna. The may be hotter than you think. If this is the case, either sit or lean on a folded towel or other cushion, or allow the surfaces to cool down some before using the sauna.

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