- What kind of haunt did you want to design?
- What kind of theme?
- Have you preferred triangular or square grid in the past?
- Have you used a central corridor for cast and crew?
- What kind of props are you going to use?
- Any funhouse style surprises?
- Any simple or complex Animatronics?
- How many actors will you be using?
- Are they going to be stationary in each room (i.e. torso tables and the lot) or will they be able to work different rooms?
- What does the other haunt look like?
Those aren't rhetorical questions. Provide answers and you will be halfway there to designing this space, and we will be able to better assist you.
Also, what are the particular dimensions of the building? 40' x 50'? 25' x 80'? 20' x 100'? (44.72' x 44.72' even?) Those specific dimensions will have a large bearing on how exactly you layout your plan.
Now, interestingly enough, I have a universal floorplan you can use, and it would be very easy to simply insert whatever room designs or elements into it. Right now it's 4000 sq ft, but I could easily cut it in half for you if you like, but let's get these other elements out of the way first.
Incidentally, Allen has a brilliant DVD on Haunt Design which I highly recommend. JB Corn's books and videos are also excellent.