## Ballast Practice Exam Question Explanation

Site Zoning Vignette and Multiple Choice

### Ballast Practice Exam Question Explanation

The floor area ratio for a suburban property is 2.0. The lot is 50 ft wide (parallel to the street) by 100 ft deep (perpendicular to the street). The required front setback is 10 ft, and the back and side setbacks are 5 ft. Which of the following building configurations may be constructed?

A. a two-story building that is 50 ft wide by 100 ft deep
B. a three-story building that is 40 ft wide by 80 feet deep
C. a three-story building that is 40 ft wide by 85 ft deep
D. a four-story building that is 40 ft wide by 65 ft deep

I did the math and picked answer C.

100'x50' = 5,000 sf (site), 5,000 sf x 2.0 (FAR) = 10,000 (bldg. sf), 10,000 sf / 3,400 = 2.9 stories = 3 stories

I rounded the 2.9 stories to 3 stories. Should you not round? I am a bit confused.

Why is it B?
drfmpower

Posts: 30
Joined: Fri Apr 07, 2017 7:59 am

### Re: Ballast Practice Exam Question Explanation

The floor area ratio for a suburban property is 2.0. The lot is 50 ft wide (parallel to the street) by 100 ft deep (perpendicular to the street). The required front setback is 10 ft, and the back and side setbacks are 5 ft. Which of the following building configurations may be constructed?

A. a two-story building that is 50 ft wide by 100 ft deep
B. a three-story building that is 40 ft wide by 80 feet deep
C. a three-story building that is 40 ft wide by 85 ft deep
D. a four-story building that is 40 ft wide by 65 ft deep

I did the math and picked answer C.

100'x50' = 5,000 sf (site), 5,000 sf x 2.0 (FAR) = 10,000 (bldg. sf), 10,000 sf / 3,400 = 2.9 stories = 3 stories

I rounded the 2.9 stories to 3 stories. Should you not round? I am a bit confused.

Why is it B?

It's a poorly worded question, but the answer doesn't allow partial floors, so answer C would be too large. Annoying, but not unrealistic for this exam.
thd7t

Posts: 381
Joined: Mon Aug 22, 2016 1:23 pm

### Re: Ballast Practice Exam Question Explanation

I get it now. I should have calculated the math for each answer to stay under 10,000sf. Thanks for the response.
drfmpower

Posts: 30
Joined: Fri Apr 07, 2017 7:59 am

### Re: Ballast Practice Exam Question Explanation

I'm sorry can someone (coach or anyone) explain this further?

Is the answer B because if we stuck with 2.9 rounded up to 3 stories would put you over 10,000 s, making answer C incorrect?

Is there a rule of thumb for rounding up FAR and when to do it?
hangryarch

Posts: 15
Joined: Thu Dec 07, 2017 7:00 pm

### Re: Ballast Practice Exam Question Explanation

hangryarch wrote:Is the answer B because if we stuck with 2.9 rounded up to 3 stories would put you over 10,000 s, making answer C incorrect?

It's B because that's the only one that doesn't exceed allowable FAR and max footprint while maximizing bldg area.
C is incorrect because it does not allow for a partial floor.

Is there a rule of thumb for rounding up FAR and when to do it?

You have to use logic -- it depends on the scenario and the answer you're looking for. That's the only rule of thumb.

Coach