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Figuring out how much paneling you will need for your sauna hot room

Whether a wood fired sauna or an electric sauna, when it comes to building our own sauna, lots of folks get tripped up about how much material they’ll need to panel their hot rooms.

We get our pencils out and start writing down some numbers.  We scratch our left ear, do some calculations, then we scratch our forehead.

“board feet, lineal feet, square feet, oh, my!  I’m not a total idiot here, but why is this so hard?”

I’ve built a bunch of saunas and still, I get tripped up on this.

Let’s walk through how to do it:

  1. What is the square feet of your sauna hot room?

Add up the length of all four walls.  Take that number and multiply it by height of your sauna hot room.  This number is the square feet of your walls.  But you also need to add the square feet of your ceiling.  Easy.  multiply the length times the width of your hot room.  At these two numbers together.  This is the square feet of your sauna room.

2.  Subtract for windows, doors and add for trim.

Here’s the secret.  Chances are if you measure all that stuff, then add back in what you’re needing for trim, odds are that your numbers are going to be pretty close to each other.  So, just go with #1 (and maybe a little more for mistakes, etc.).

Now you have TOTAL square feet of material you’ll need to panel your sauna hot room.  But we need to convert this to board feet.

uggh.. this is so hard to explain.  Let me just try to roll through an example.

7’+7’+7’+7′ = 28′  That’s the perimeter of my hot room

7′   That’s the height of my hot room.

28′ – perimeter of hot room

x7′ – height of hot room

196′ = that’s the square feet of my walls

7′ – length of one wall

+7′ –  length of the adjacent wall

14′ = square feet of my ceiling

196′ – square feet of walls

+49′ – square feet of ceiling

~ 250 = square feet of sauna.

5″ exposed height of t&g paneling

x12″ number of inches in a foot.

60″ – square inches of 1′ of paneling.

x.00694444 –  1 Sq. Inch = 0.00694444444 Sq. Foot  (this is a formula number)

0.41664 – square feet of one board foot of 5″ paneling.

/ 250′ – square feet of sauna.

600 – lineal feet of 5″ paneling needed to panel my sauna.

/ 14′ – length of boards.

43- number of 14′ boards needed to panel my sauna.

This is the best way I know how to figure out the number of cedar boards to panel my saunas.

Again, there’s all kinds of weeds we can get tangled in, trying to subtract for windows and doors and durarock corners behind our sauna stoves.  I’ve built my share of saunas. It’s crazy how subtracting for all that is about the same amount you’ll want on hand for ripping trim and making sauna hot room door.

So, order 37 boards, 14′ long and let start paneling our hot room!

a sauna hot room, with blocking for sauna benches, almost ready for tongue and groove paneling (needs foil vapor barrier)

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5 thoughts on “Figuring out how much paneling you will need for your sauna hot room”

  1. There are many ways to calculate the amount of lumber you will need for your room ( I prefer the method I’ve used for thirty years plus, as it is simpler and more accurate )
    And as I used to tell my students, when figuring material quantities, always check the math, or have someone else look it over for you; as errors can be costly…
    (The ceiling area you’ve used here Glenn needs to be checked, your order is short…)
    Thanks and good luck…

  2. What if the vapor barrier is polyethylene? Do I need to replace it or is it alright? I was told by someone at the hardware store that it’d be fine, but am second guessing this advice now.

  3. Grady: My cabin sauna (25 years old) is poly. My backyard sauna (20 years old) is foil. I could tell you to take it down or leave it up, depending upon how you’d feel better. In other words, if your at the poly stage, rip it up and start again. if, you’ve already tongue and grooved, move on and you’ll be ok.

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