Decks, Patios, Porches and Docks - 1st time shed builder

I've come up with a brainstorm to build a "Boom Boom" room in the back of my house. The dimensions are 15*22 and will be the same height of the deck that i'm building that is 6-7". The idea is to enter the this space from the deck with no steps included. I've having trouble deciding on the type of foundation i need to put together and if i need to complete this project on a concrete slab.

If this is going to be attached to your main structure, you have building codes to deal with. a 6'7" ceiling height won't pass muster. Check with your local inspector to see what you can and can't do, before you start. It will save you a lot of time and money.

If the "Boom Boom room" is over 120 sq. ft., you'll need a bldg. permit. That's assuming that it has more than 6' of seperation from your existing residence. If it's closer than 6', you'll need a permit, regardless of how big it is.

Ceiling height is going to be an issue, as Larry pointed out. If the room needs a permit, 6'-7" won't fly. If it's less than 120 sq. ft., thereby avoiding a permit, a 6'-7" ceiling means that your door opening is going to be about 6' high or slightly less, and that is going to draw blood from the top of the head of about 1/2 of the folks trying to enter it.