This is about how much firewood I use for a sauna session:
Left hand: The firewood
Right hand: The kindling to get it going
If you invest in an efficient kick ass wood burning sauna stove, you don’t need a lot of wood.
If you invest in an efficient kick ass wood burning sauna stove, you don’t have to mess around with the fire much, if at all. This means that you can sauna, and chill, and dig yourself while passively monitoring the program. You can party with friends and family pretty much hassle free (but many of us love tending to the fire, which is another article forethecoming).
Less wood means less emissions, smaller wood piles, a more low key footprint and disposition, and an all around a better sauna experience.
Are you using more than this amount of firewood for your sauna sessions?
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Not in picture
A sheet of crumpled newspaper or a piece of birch bark (Nature’s gasoline). Load firewood then kindling. You can read more about upside down fire here.
Editor’s note: This article was written in September, where the outside temp. was about 40°f. (4°c.). For winter saunas, we bank on two more of these logs. By dampering down the fire, we retain more heat in the hot room (vs. going up the chimney).
15 thoughts on “How much firewood do you use for your sauna session?”
I am in the process of designing my “off grid” sauna for our northern Wisconsin cabin and i have a question regarding venting. I would like to put the wood stove just to the right of the door inside the hot room. Venting outside air to the bottom of the stove is not a problem but from everywhere i read they recommend venting to the dressing room and the opposite side of the room from where the stove is. Is it possible to have the outlet vent on the same wall as the inlet vent just positioned higher on the wall?
I’m trusting you’ve typed the word “ventilation” into the search bar above, and read this post here.
My opinion is that ventilation is more of an art than a science. We can create perfect ventilation for our own sauna, but when we develop a graph and try to preach that ventilation plan to all/others, well, it doesn’t always translate. Different stoves, different hot room size, etc. Every sauna has its own soul. So, we need to feel our own sauna and vent how it wants to vent.
As a general rule, and from my decades experience:
1. A crack along the hot room door.
2. A vent down low, near the stove, from the outside.
3. A couple vents up high, opposite wall, from the outside. With “chutes”.
#1 is really important as it de pressurizes the air, as we open and close the hot room door.
#2 is really important to feed the stove and create air flow.
#3 is really important to help air move and co2 air escape.
You may have read this post about sauna ventilation, everyone has an opinion..
For venting the hot room, I like a vent down low to feed the stove, and a vent or two up high, opposite wall with “chutes” so a guy can control the action. All vents leading to outside, for fresh air.
Venting from hot room to changing room is not the best way to roll. The atmosphere in the cool down room is best as its own independent event.
BONUS: Keep in mind the infinite atmospheric possibilities of your cool down room. By simply propping open the hot room door and/or the man door to the outside, we can quickly create the climate of our cool down rooms to fit the vibe.
One of my favorite moments of a sauna session is hanging out in the cool down room with a couple buddies (and a cold one). Our bodies are warm and freshly steamy (after a cold plunge). The air in the changing room is cool.. almost cold. The steam is everywhere. There is no urgency to get back into the hot room. The atmosphere is as if on a mountain hike, 12,000 ft. above sea level in Hawaii, amongst the clouds, endorphins rushing and smiles and laughter happening. That’s the vibe we can get in the cool down room. Infinite venting possibilities just with the doors opening and closing and air flowing that way.
OK Glen and Co., you have spread the sauna virus here! While my wife is not too thrilled that I have caught it, I am now on the long therapy cure of building my log sauna in the foothills of the Cascade mountains in Eastern Washington. It will be wood fired, on stone foundation and I am pleased with the many posts, questions and replies your other patients have submitted and responded to.
Keep up the good work!
Lots to learn here to get it right, don’t want to make the mistakes, others may have, as wife is giving me only one chance at this, no do-overs! Always interested in photos and ideas on log saunas.
I use quite a bit more than you do. I’m heating a bigger space with a bigger Kuuma and starting with a cold soaked building. I use about 4x what you’re holding.
Well, I remember when you were considering your sauna project and how you resigned yourself to the deep breathing of your existing old school log structure as home for your new sauna, and the plan to combat the thermal inefficiency with more BTUs. You have a robust wood production system and know how to optimize and disrupt without any further corporate business jargon, and if others could see your awesome wood piles, they’d be willing to fill out TPS reports and join you on the bench!
I measure wood in “banana boxes”, which hold 1/100 cord or about 0.8 cu. ft. of solid wood (80 cu ft/cord is what I’ve read.) For me, one box is not enough, about 1.5 boxes is good. I use a mixture of primarily bigtooth aspen, black birch, gray birch, along with whatever else comes from my woodlot. Aspen and gray birch are quick heat, black birch is good hard coals.
My best fires come from dry wood from covered woodpiles. Moist wood gives me a slow start to the fire. When things are going well, the temperature rise is greater than 1° F per minute, but that means it still takes 1.5 to 2 hours to get it from 30° to 170°. The stove is the small Kuuma, the hot room is 7’x7’x7’.
My venting schedule is: window cracked in cool room, 6” gap under door to hot room, adjustable vent along top of wall in hot room. The latter takes advantage of an open eave/soffit – the roof insulation begins just above the top of the exterior wall rather than filling the space between the wall and roof sheathing. Opening the 4’ vent ½” provides 24 sq in vent area. When the wind is from the north, I get a slight cool breeze on my shoulder with the vent open; otherwise I get heat flowing over me to the vent. The Sauna Spirits decide which!
Remember that movie Stripes, where the new soldier recruits are introducing themselves, and Bill Murray says “I want to party with you..” !
The way you describe your sauna preparation is much aligned with my consciousness. Part of the virtues of wood fired is how we are able to connect with our saunas, “the Sauna Spirits”, as you rightly define. This spirit is not a Finnish exclusive, or American, or Canadian, but other worldly, and comes up way short if trying to describe it to others who have not experienced and felt it for themselves. But I am right there with you, brother.
Couple other minor notes:
1. “My best fires come from dry wood from covered woodpiles.” Exactly. But not too dry. In this podcast with Daryl Lamppa, we learn about moisture content, and wood that is too dry is no bueno. I like to toss in a “yule log” that is a little more beefy and moisture content in the 20% range, once the Kuuma is rocking with a good base of coals. This gives an extra punch of lämpömassa producing btu’s.
2. “… it still takes 1.5 to 2 hours to get it from 30° to 170°.” I’m 45 mins. to 1 hour for that rise. My backyard hot room is smaller than yours, 6’4″ x 6’3″ x 7′. Have you tried the upside down fire method? And you will need a serious waiver form from Daryl Lamppa if you open your ash pan for the first 15 minutes after lighting the match, but a temporarily open ash pan allows for infinite air in the fire box, jet fueling the kindling, and getting things rocking with zero smoke. I’m always around the sauna area for those few minutes that the ash pan is open, usually tinkering or splitting some firewood. (Safety first). I have not needed to clean my Kuuma window glass in over a year now, since I’ve adopted the upside down fire method.
Hello Glenn, I am wondering what is the best option for heat shield behind wood burning sauna stove? Foil wrap then leave 1 inch spacer on the wall, 2 inch spacer on the ceiling then 1/2 inch concrete board? OR is using 3/4 inch cedar t&g or use 1/2 inch concrete board tight to the stud wall then the foil. Right now as it sits I have it set with stud, foil, 1” of 1/2” copper pipe as spacer, then concrete board. I am just a little worried about the foil being the only barrier between an insulated wall and the sauna hot room? What do you think is the best idea? Thanks Daran
Yes, if you can, I’d set it up as:
1. studs, insulation.
3. cement board, screwed to wall.
4. 1″ spacers
5. 2nd layer of cement board, starting about 6″-1′ off the floor.
The gap (between #4 and #5) is the real key, as the air cavity creates a thermal bridge between the mega hot and the wall.
Hope this helps!
Glenn, yes this helps!
I did used the 1 by 2 wood spacers as a recomended (by some) option. With the 1” copper pipe spacer on the walls, 2” copper pipe spacer on the ceiling. Would it be best to remove the 1” by 2” wood spacer on the studs in this heat shield area ( ceiling and walls ) or is it ok to leave it ? I did put a 4” air space off the floor, but I will adjust these things. The cold air comes in the bottom 6” gap is there another gap at the top of the wall or out the 2” gap at the top?
I’ve built many saunas with 1x2s as spacers. Technically this material is a “combustible” but i’ve not had any issues using this material/medium to establish the air gap.
Hello Glenn, prematurely to having this all figured out I have the foil up the 1 by 2” wood spacer around the whole sauna room and 1” copper pipe spacer on top of that. then instead of putting the cement board on the wall I put it on the wood spacer and all cuts where done accordingly. So it looks like. The best thing to do is to just take it all down and start again, this is ok. I have the extra cement board on have. This is to keep the cement board tight to the wall and have no piece of wood, have it all non flammable. Is this what you were saying ?
Should I take it off and start again, this does seem like the easiest, this is to keep the Cement board tight to the wall with no wood spacer? The copper spacer is between the first and second cement board. This is what I am about to do.
Hi Glenn , is there any sealant you would recommend for the western red cedar in the hot room ?