Our old sugarhouse housed a 2x6...that was it. Enough room to walk on either side and just enough to open the door and add wood....Then we expanded into and added on a couple sheds...like a shanty town. Functional until the 2x6 became too small.
We did a bit of calculating then some more and came up with a 28'x32' with footings which extended beyond the building to add to. I did NOT want shanty town coming back. Instead of footings we went with an Alaskan slab using 2" foam under and 24"x18" foam forms. We decided on 28'X60'. We are three years into it and 32' X 68' would have been better. Not much bigger, but the tractor and a SxS would fit better. the SxS is now in a small shed of it's own.
We stepped up to a 3x10 evaporator and have 1 4'x16' sap tank and 1 4'x12' permeant tank in the room with the evaporator. We have 12' x 12' RO room which also houses our well pump controller and hot water tank. We have a kitchen outside the RO room and open to the evaporator area. We went with 12' walls and have a floor with 3' knee walls above the kitchen and RO room. We also added a cat walk/platform above the garage space which houses the fuel tank for the evaporator (we ran the fuel line in conduit under the concrete along with power to the evaporator) and a tractor and excavator.
It is a large building and does work very well for us. The size difference of what I kind of wish we went with is just a little more space around the equipment so we don't have to move it out in the winter for a quick project.
They say double what you think is good for now and you should be okay. Plan on a RO room (we have a direct vent heater which uses very little propane to heat our 12x12 RO room) and kitchen. Plan on having hot water. Plan on a 3x10 or evaporator if you are happy with a 2x6 (we now have room for a 5x14).
Enjoy building it.
Mike
Tapping since 1985 (four generations back to early to mid 1900s). 200-250 taps on buckets and then tubing in the mid 90s. 2013- 275 taps w/sap puller 25 gal. 2014-295 taps w/sap puller 55 ga. (re-tapped to vacuum theory) 2015-330 taps full vac. 65 gal, 2016-400 taps 105 gal, 2017-400 taps 95 gal. 2018-additional 800' mainline and maybe 400 new taps for a total near 800 taps. 2x6 Leader WSE (last year on it) supported by a 250 gph RO.