It’s not what you think: good venting actually makes your sauna feel hotter

It makes sense to think that you want to keep you sauna hot room tight, with a minimal gap along the bottom of the hot room door and very well sealed walls. And this is partially true.  We want to contain heat.  We want the heat to resonate in the hot room with good, dense lämpömassa  (think heavy stone wood fired pizza oven vs lame ass thin metal toaster oven).  

But with venting, I’ll be the first guy to admit that I used to build my saunas tight, trying to contain heat within the hot room with minimal air gaps.   Then I went back to Finland.  In Finland, the pros call for about a 10-15cm gap along the hot room door.   You crazy?  I was always thinking a gap for a mouse, tops. But 10-15 cm? My cat can fit under that door gap.  

And what about wall vents? It makes complete sense to install them and have chutes for opening and closing, but truth be told, I wouldn’t open the wall vents much. My thinking was, to really crank the heat, shouldn’t we keep the wall vents closed?

No, no, no.  

Once again, as with many things in life, the opposite is true, and the Finns are right.  (Insert political argument about education, health care, public transportation and/or salmon soup here).

How is it that a well vented sauna can feel hotter than a poorly vented sauna?

Any idea?   

Need a clue? 

Ok, try this: ever stood outside on a frozen lake on a sub zero calm day?   Not so bad, is it?

Now, compare: ever stood outside on a frozen lake on a sub zero windy day?  You don’t last too long, do you? “The wind blows right through you, it’s no place for the old.” – Fairytale from New York, The Pogues.

Wind chill will kick our ass. 

Follow this principle with sauna.  

A well ventilated sauna creates air flow (circulating good heat).   Instead of wind chill, a well ventilated sauna creates a hard to notice yet gentle breeze of heat.  

You won’t necessarily feel it, but a well ventilated sauna will feel hotter than a poorly ventilated sauna as warm air is passing over our bodies on the sauna bench.  A very subtle yet slight hot… breeze. 

You can probably sit in a poorly ventilated sauna for a longer time than a well ventilated sauna. What’s worse is that in a bad sauna, you will leave the hot room wiped out, exhausted because you’ve been breathing stale, poorly oxygenated air.  

What do we do if our saunas are poorly ventilated?

Two things we can do:

1. Let’s pop in a couple wall vents. Borrow or dig out a simple hole saw and drill out a couple holes. Set in dryer vents and flash around the inside with chutes.  The mobile sauna shown here illustrates wall vents..
2. Let’s make a wider gap along our hot room door. Unpin your hot room door, lay it on saw horses, and cut off a couple inches along the bottom with a skill saw.  

Yes, it is counterintuitive 

Good venting actually makes our sauna feel hotter.  

And good venting helps keep our saunas fresh and smelling clean. When we apply the Bake and Breathe method, along with good venting, our saunas don’t seem to be needing to be cleaned much, if at all.

You can read about the bake and breathe method here.

You can see a wall vent being installed here:

So, It’s not what you think: good venting actually makes your sauna feel hotter. And good heat makes all the difference.