We are in the planning stages for our horse barn and I'm so confused it hurts. The first and biggest decision is design. We are going to talk to a barn builder locally to get ideas on the most economical way to do things, but trying to decide whether to have an attached indoor or to do a detatched indoor as phase 2.
Regarding indoor, if we go attached, there are two main options with an A frame, 1. Having stalls all down the length of the arena, an aisle, and then the arena 2. Having a more traditional looking aisle barn on the one end (width) of the arena. Option 1 ends up more square feet, but I would imagine costs to finish will end up around the same.
The other thing I've seen people do is T the indoor off the barn. I'm not sure if that may cost more than an A frame building, but I do like the looks of it.
I would LOVE to see pictures of your indoor/barn combination and how you have it set up! Plus any things you would do differently or "live and learn" type moments when you built your barn. I'd like a fire system (sprinklers) but not sure the added costs, or the costs of running that into the indoor to water the dust down.
And another big question, how many stalls did you decide to go with? We field keep our horses, and that won't change.
I would like the indoor to be a somewhat separate structure (even if attached) to improve air quality for the stall area of the barn. The riding in the arena will create some air borne particles that will contribute to an already dusty environment.
Also your costs will go up the wider the area you are trying to cover.
Although the earthwork to create a level area for barn and stable may make going wider cheaper than longer.
To get a real feel for cost, it will require the builder to do a site visit.
The most economical is a metal clear span building for the most width you can afford and then lean to from it on either or both sides for stalls and other.
All under one roof makes labor the most economical and comfort and being able to work in all kinds of weather.
The reason is that you already have one wall up when you use the wall of the arena to frame the overhang where your barn will be.
If you are worried about air quality, sheet the wall between the indoor and the stalls, so they are two separate air zones.
From all the many, many barns I have seen and BO and BM I have talked to, that makes the most sense all around.
Any other design is less ideal, but if it is someone's preference to have a different barn/indoor design, or the location demands it, why not?
I prefer indoor arenas that are separated from the barn for air quality reasons. You definitely don't want your stalled horses breathing arena dust all the time, and no matter what footing you use there will be some level of dust. Even if the stalls run alongside the outside edges of the indoor and are separated by a wall, you still lose any air circulation for the indoor from that side. I prefer indoor arenas that have a lot of fresh air flow so that the exercising horses and riders are breathing the cleanest, freshest air possible. That having been said, if you live in a harsh climate where you are keeping the indoor closed much of the time that may be less of a consideration.
Regarding a watering system for your indoor, remember that if you live in a climate where the temps drop below freezing you will have to empty those waterlines each fall and you won't be able to use the system for half of the year. Perhaps you could consider a hygroscopic footing additive like mag?