I’m going to assume that you are planning for a barn in a warm weather location because you mention mesh stall doors for ventilation. My barn is in coastal NE Massachusetts and we get weather that may make much of what I love irrelevant for you, but I’ll write a book anyway.
I looked at the old barns in my area, and they were oriented east/west, so that’s what we did, and there is generally a breeze through the barn in the summer. And there is a relatively solid face to the north, where our icy weather comes from.
Love the overall dimensions of my barn. The stall block has 11 stalls plus one half stall. Stalls are 13 foot square (except for half stall), and the exterior walls are insulated. Aisle is at least 12 feet. Walls between stalls are 5 feet high, front walls 4 to make it easy to peek in. Both have grillwork 3" on center so feet can’t get hung up. They are designed so that walls can be taken down if necessary. Sliding stall doors have yokes so horses can be friendly and get a view. Walls and doors are made of rough cut oak. Don’t bother with pine, which horses love to chew. Windows are 4x4 with hinged grillwork on the inside. They slide into pockets, and screens fit on the outside. End doors slide into pockets, and there are sliding screen doors too. There are GFI plugs up high in each stall for fans, and they all work off a single switch.
The stall block has an aisle off to the side that attaches to the old part of the barn (1904). This has a brick floor in the tacking up and wash stall areas (which are heated in the winter). Two tacking areas plus the wash stall can be used if several of us are going out at the same time. There’s hot water in wash stall which has perimeter drains that outflow through a dryer vent cover, which keeps cold air from coming in. The back wall of the area has kitchen casework from a house being renovated which gave us a counter, sink, and large drawers under the counter that hold everyone’s grooming stuff. Beyond that the tack room with a bathroom.
There is a separate room for feed and there’s some blanket storage in there as well (more kitchen casework). Remaining blankets are stored upstairs in the loft. The lockers for open feed are mouse proof. The barn cats patrol the unopened bags. They have cat doors to the basement and the hayloft, or any door that closes the barn up EXCEPT for exterior doors. Don’t want any uninvited visitors! And to assist in that, we put metal hardware cloth over all the soffit vents.
Huge hayloft overhead that covers the old and new part of the barn with stairs for access. Fits a year’s worth of hay and shavings, so no hunting around for those items in the winter. There’s a hay drop right outside the half stall, so that’s where the hay and shavings for the next few days are stored. Wheelbarrows fit under the stairs to get them out of the way, and there’s space for pitchforks, brooms and shovels right there. Opposite the wheelbarrow storage there’s a sliding door to a garage that the manure trailer backs into. So nice in a storm to be able to dump manure without going outside.
Building code required that we have a full foundation, and the barn site is on a slope (end to end) so the barn floor is off the grade much more at one end but we built an earthen ramp. The foundation is filled with 4 feet of crushed stone (aka gravel) so drainage is no problem. Below each hydrant is a removable drain so there’s access if needed. We also installed a fitting on each hydrant pipe to make it easier to take them apart for repair.
Stalls floors are mats over stone dust and have been great for 16 years (so far).
Barn aisle is concrete. Stable block ceiling is off white metal roofing over insulation. We power wash it once a year. Reflects light back into the barn keeping things bright.
Exterior of barn is Hardiplank. Love it. We painted it 16 years ago and it still doesn’t need a repaint, and looks really good.
We have hydrants at each end of the aisle and in the middle where there’s a side door out to the parking lot. Also exterior and interior plugs at the front, back and side doors. Useful for farriers and others.
We have good access for vets, farriers, large delivery trucks, snowplows, firetrucks, everything. And re: safety, the barn has hard wired Rate of Change Heat detectors. FYI smoke detectors are unreliable below 32 degrees and are a pain with dust and spiders in any event.
What I don’t like: we have to lead the horses to paddocks, but the typography and site conditions left no choice.
I wish the barn had a separate water meter so I could better control usage, but the town wouldn’t allow it.
There are two paddocks that we couldn’t set hydrants in because horses would’ve been able to reach them, but they are near enough that we can run hose. Paddock layout was set before we moved here and the ConsComm wouldn’t let us change it much Don’t like that. (We have electric to all the winter paddocks: useful for deicers.)
PS: If you decide to do dutch doors on the outside of the stalls, please make sure that you install hardware for opening them from the inside or outside in case of fire. And if you possibly can, invite the fire dept over for a walk through so they know where they can put horses and have an idea of the layout. We do a horse handling session for fire fighters every few years just to give them some familiarity. At the end, we have a participant walk through in full gear with a respirator so they can see how the (previously) docile horses react.
Here endeth the book.