The answer is very local and dependent on types of construction.

South Florida coast is not a borderline area - basements are not a reasonable option. As you move North, basements become relatively cheaper. But unless there is something unusual about your local soil conditions, you don't really have an option.

Now - you should be careful before you get too far. 3rd floors are not a great option in many areas either. You are blocking someone else and for this reason, jurisdictions block 3rd floors. My permitting is getting held up because of height requirements and I am only building 2 floors. In my area, you can have a third floor but it can't be near the setbacks - only in the middle of the house. Our edge height at the ceiling plane is limited to 22 feet - so 19 feet for the actual room heights(10+9), and then 1.5 for between floors. Sounds easy enough but it is based on average grade for the entire lot - so the house is on the highest part of the lot (and why wouldn't it be?) so that adds maybe another 2 feet.

Thankfully we are building 2-3 feet off setbacks so we should be fine since you get 1 foot up for every 1 foot off. But close enough that everything must be labeled to ridiculous detail.

There is usually an overall height requirement too. In my area, I have seen 38-42 feet which usually does allow a 3rd floor in the center of the house but again not on the edges assuming a sloped roof. And then you get have to plan dormers and such for windows - possible not something done in Fl.

Have your parents live in the first and second floors and you live in the basement or 3rd floor. Now, would you rather live in the basement or third floor?

I would not want a basement in your area of Florida

I wouldn’t want either. Is there no way to include the in law suite on the first floor? That’s a common solution in my area. By the way, there are several 3 story homes in my area ( land is expensive ), most homeowners hate them, find them very impractical, even with an expensive to maintain elevator.

Why would you only put a square house on a long lot like that?

60x60x3= 10,800 s.f. Are you sure you need 3 levels?

"60x60x3= 10,800 s.f. Are you sure you need 3 levels?"

He's building an "in-law" suite. I'm thinkin' 10,800SF might not be enough.

No way can a 60x60 house ever be attractive or function well. Unless you are into “warehouse chic”. And your municipality would approve something commercial like that.

You need professional design help. Now.

if your parents need to move in with you, are lots of stairs really a reasonable option, or are you going to make them stay in their suites? I mean, most older people opt for single-level homes for safety and to save their joints...

Have you considered an entirely separate unit detached from the main house?

Neither basement (particularly a completely below grade basement) or a third level may be appealing to older couples or individuals.

Why not design the first floor for the elderly and let the "younger", more mobile home owners occupy the second and third levels...? Hmmm?

I would think living in a basement in Florida would be akin to wearing this T-shirt to a shooting range:

Wouldn't consider a basement here in PBC for any reason. Agree with the others about having in-law quarters on the first floor or detached, if possible.

Thanks to all those who responded :) With 3 kids under 4 and 2 on the way (twins), it is important to us that all the bedrooms are on one floor, with the rest of the living spaces on the Main.

I know 60 x 60 might seem boxy, but we are quite pleased with the designs, and it gives us enough extra room on our lot for a back patio/lanai, a pool and enough green play space for 5 kids and 3 dogs.

We currently live in PA and only ever had homes with a basement so I wasn't aware that would be a challenge in FL.

I'm a bit anxious moving thousands of miles from my elderly parents for the first time, and was hoping we could find a way to accommodate them (a detached option isn't possible with our plans), hence why I was hoping for a basement or 3rd floor suite...

Looking at the exterior, I'm guessing the interior is going to be dark unless the back is completely open to the lanai. I also still think you can do better than a square house on your property since that house looks like it would be better on a wider but not deep lot.