• Yes, I think NCARB's answer here is 100% wrong.  You don't use the setback to calculate the FAR.  The FAR is calculated using the entire site area.  Then you try to get as many sf to fit inside the setback, at the max height allowed by zoning.  This question is complicated the fact that it's saying the setback change for different heights.  What does the zoning say is the max height for residential in this zoning?

The tallest building (even with the increased setbacks) will be biggest sf.

I'd take up this issue with NCARB.  Hope this helps!

Rebekka O'Melia, Registered Architect, NCARB, B. Arch, M. Ed, Step UP,  Step UP ARE 5.0 Courses

• NCARB would you please explain. your practice exams that we are trying to learn from have errors.

• The NCARB question is not wrong - you have to carefully read the problem (which is my biggest problem, I am always looking to skim).

The problem states: "the Owner wants to build each story to the extent of the required setbacks" - this right here tells you exactly what you need to know. They are GIVING you the FAR (4.0) to calculate how many stories you can build -they are not asking you to calculate the FAR. So in this case, you need all the information the problem presents.

Your lot is (190x60) = 11,400SF - with an FAR of 4.0, your maximum buildable [or gross floor] area is 45,600SF for the building. But, the problem states the Owner wants to maximize the building to the setbacks. So you have to calculate each scenario with the setbacks and find which of the scenarios yields the greatest buildable area without exceeding 45,600SF.

If your building is 1-story, you lose 20ft to side setbacks - that means your floor plate is (155x40)=6,200SF. Since you are only allowed 1-story in this scenario, no point is further calculating. This answer is listed, but let's follow through the other scenarios to see if there is a greater (maximized) choice.

If your building is 2-stories, you lose 30ft to side setbacks - that means your floor plate(s) are (155x30)=4,650SF. Now x2-stories, you get 9,300SF. The answer is not listed, so let's move on.

If you building is 3-5 stories, you lose 40ft to side setbacks - that means your floor plate(s) are (155x20)=3,100SF. Now x3-stories, you get 9,300SF (same as above scenario). But in this scenario/setbacks, you are allowed to build up to 5 stories. At 4-stories, (3,100x4)=12,400SF. At 5-stories, (3,100x5)=15,500SF. I suspect this would actually be the right answer, but there could be other factors at play like building heights and it's not listed.