They are actually above the sauna at upstairs that is storage space, chimney goes trough that space, it is made of bricks and building is wooden. There is small ledge at chimney where it pops trough roof of sauna, that is floor of upstairs storage space and it is such place where they can fit. Sauna heats chimney to hand warmth up there, so it is certainly nice place for them to be, there is also lot of straw and bit of sawdust and as that is only insulation whole roof of sauna and section of floor at upstairs get warm, probably quite nice for them to fell sleep and hunt mice.
Sauna itself is 3x3x3 meters roughly, mine is from early 1950's, so it is far larger than modern saunas, but it does heat up quite fast, i load up firewood and after those start to be burnt I add another set and sauna is ready to use, I'm not sure how long it takes, but perhaps 30minutes from +2C to +80C, then I usually get temperature to bit over +100C, about hour in there and I must say it is quite relaxing, so much that I often fell asleep after a sauna when cooling off. I'm not 100% about my sauna temperature meter being perfectly accurate, I should sometime check that with another one.
Best bit of Sauna is that it cleans your skin, as in shower you really can't get rid of all dead skin, but in sauna all that dead skin that causes itching and feeling of tight skin etc. gets off without much rubbing.
Then there is those modern electric saunas, that don't burn wood, but haven't found single one that would of worked well, in those steam burns and still air feels so dry that it burns lungs, where as at least my wooden sauna has softer steam and I haven't had breathing issues even when using very high temperatures.
As I make my own firewood (I have little forest where I grow trees), it is of course bit more work, but not too much, I tend to warm sauna 1 or 2 times a week. Summer time more often, those mosquito and horse fly bites need to be taken care of and sauna cures that itch too, or maybe it is a placebo effect, but no itching bites after sauna, what ever the reason.
Some say that moose fly does not die in sauna, well at least they stop moving, at autumn when I go to collect some berries from forest those tend to get into hair, there can be more than 10 of them and they are bit difficult to get rid of, but they leave voluntarily after a short while in sauna, or at least bit easier.
There would be more of them walking inside the shirt if I would not have net hats and net shirt that do protect quite a bit, but still not perfectly. They have never bit me, but just crawl under the shirt and in hair, quite annoying to get rid of, but luckily they don't attach too tightly to my hair, for some they grab really tight. Might have something to do with that I use wood tar shampoo, I like the smell of tar and I use wood tar for many other things too, bolt threads, skies etc. No need for complex chemicals when one stuff can do it all
I have one old pic of my sauna, I have replaced stones and made repairs to chimney after this pic, but can't find never pic now:
Bottle on the wall was there when I moved, reason is rather unknown to me, maybe they did warm the sauna until water did boil
Funny thing is that I did not like sauna when I was young, I used to get black outs when coming out from the heat, but haven't had that issue with this sauna.
I don't know what Kiuas is in english language, it is heat source of sauna, next to it barely visible in pic is water heater, I burn wood under that and it has water container, direct translation would be cauldron, but it is not the same, since last summer I have only used that to heat water, I have got my electricity consumption to be really low, also I do all the cooking with wood heated stove, lot of axe swinging needed, but good bit is that I don't need to pay as much electric bills. Also wood is renewable energy source and making firewood keeps body in better shape.
