Community Space: Assembly Occupancies

It does not matter if you design your space to be a home and then decide later to host tours or building workshops. Once you open it to the public, the space will no longer be considered just a residence and you will need to acquire adequate permissions and permits in order to continue using the space for public use.

An Assembly Occupancy is what the Building Code considers a space for public accommodation that is not a business, school, or industrial site. Usually the space will be deemed an A-3 occupancy, which is for public spaces other than restaurants without fixed seating. So, if you want to avoid having your classes shut down and avoid having to do a lot of expensive upgrades to the space later to make it meet Code, plan now for it to be considered an Assembly Occupancy (minus the expensive fire sprinklers). It will cost a little more. It may take a little longer in design. It may not look exactly the way you hoped. But, you may find that these accommodations will make your home perform better for day-to-day use anyway.

Plan ahead. Spend some money now. It will cost much less now than later.

You will likely have to design the structure according to stringent rules for occupant safety and accessibility.
To make a bathroom that is accommodating for everyone (and doubly so if the space will ever house a public function like parties, tours, or workshops...), use a 3 foot door, so people with crutches or in a wheelchair can use the space. Include a minimum 5 foot round empty space (5 foot is the spinning diameter of a wheelchair) and place the sink, toilet, and bathtub around the outside of that. Use a wall-mounted sink and make sure there is a 26 inch high clear space under it so wheelchair users can wheel up to the sink and use it. Add ADA-compliant hardware and include a floor drain in the center of the space with a beautiful cover on it. You may find that you will thank the Code for this requirement someday when you need to wash the skunked dog or dump buckets of mop water from some minor disaster and can hose the place down when you are finished. Put a sign on the bath noting that is a handicapped unisex bathroom.

There will likely be maximum hall lengths and maximum distances between the furthest corner in a usable space and an exterior door (usually 75 feet). Sometimes they will make you install mechanical ventilation and electrical outlets every 7 feet. There will likely be sewage/septic requirements and you will want to have a drinking fountain or a filtered water bottle available. The publicly-accessible parts of the building will have to be handicapped accessible. This is easier if you just plan a minimum of 3 feet clear floor space around every obstacle (like a curve in the planter), plan 4 foot wide hallways on the public corridor, and make all stairs at least 36 inches wide at the inside of the railing (That is about a 40 inch wide stair tread in most cases). The area on the handle side of a door will have to be open (without projections or walls in it) a foot or so beyond the door is wide. There will not be able to be steps between the public parts of the space and the exterior or they will require rails. If you plan on cooking greasy foods and not just bringing cold foods and using crockpots for your guests, that means big grease traps and expensive ventilation. (If you use crockpots you will want to have lots of counter space and extra plugs.) Smoke detectors will be required and possibly a fire alarm. You may have to install a fire sprinkler later. (It can be fed by the pond in some cases.) There will likely have to be a phone in case of fire so you can call the fire department. You will need a mop or service sink in the mechanical room, which you should have anyway if you really want the space to work as well as possible. Install exit signs to guide people back outside.

The key ingredient here is to make sure you use the services of a licensed architect either now or later to make sure you have all the things you need to meet the Assembly Occupancy requirements. We are not attempting to serve as architects here and do not claim to have knowledge of your local Code considerations or what your permitting authority will and will not accept. However, this area deserves some careful consideration and we are offering some guidance to make it as painless as possible for when you hire a local architect to help navigate the process.

There is a great mounting height diagram to help you make your bathroom ADA compliant from the outset at http://img.docstoccdn.com/thumb/orig/159038643.png