Are you talking about a slab for the entire house, or just the patio? I've lived in a slab house for 33 years, and hated it. The floor is harder on your back and feet, and anything you drop is a goner unless you put a resilient floor on top. In FL, under certain weather conditions, the floor would actually sweat. Basically, warm, humid weather after cold weather. Our barn here in upstate SC (Hi neighbor!) sweats during those conditions. It can be mitigated by putting insulating foam under the slab. Another issue that FL slab houses have is plumbing under the slab- there's no way to make changes or repairs without actually cutting and jackhammering the slab.

As for the patio- the sun will warm it some in the winter, but in the summer, it will be uninhabitable. A raised deck will be pretty hot also. Anything facing west in the South is gonna be hot unless you have mature trees to block the sun. We have a deck on the back facing NNE which is nice in the summer, and a porch on the front facing SSW, which is nice in the cooler months. Our deck in the back is wood, raised off the ground, and the front porch is concrete slab-on-grade. I don't really notice any difference in temperature, but the concrete is of course more durable.

Both methods have pros and cons. Concrete is durable, and can store heat to help smooth out temperature swings, the trick is keeping it from getting too hot in the summer. A crawl space makes it a lot easier for plumbing, electrical, and HVAC installation and service. Many find a suspended floor to be more comfortable.

Stained and scored concrete floors are very popular where I live. The slab has to be practically perfect with no chips, paint splatter, etc. We had way too many "bad spots" to consider stained concrete but it was never an option for the reason given by mushcreek. Concrete floors are hard on ya.

I lived in a house with a finished concrete slab as the main flooring for about 5 years. Overall, I liked it a lot, especially the look. However, I relate to the concerns mentioned by the previous posters. I lived in the northeast, but my floor would still "sweat" a few times during the summer. Very weird experience, but rare enough to not be a huge issue for me. It is indeed a very hard surface, which can be hard on our body, especially if you have any joint issues.

Regarding your question about efficiency, my house was definitely very efficient. Much more so than the old farmhouse on a 200 year old basement I have now. If you put a significant amount of insulation under the slab, you will have a very efficient home. The typical passivhaus approach, the most rigorous efficiency standard right now, is typically done on a slab because it is much easier to air seal and insulate than is a basement or crawl space.

We had radiant heat in our slab. Because the slab is a tremendous thermal mass, this is a very efficient approach if you will be keeping the house heated throughout the winter. For a second home, this option can be annoying because it takes the slab quite a while to come up to temperature. I had this issue because I was traveling a lot at the time and would turn the heat down. When I'd come home, it would take about 12 hours to bring the house temperature up just using the slab heat. However, we didn't have insulation in our slab because it was a converted barn with a repurposed slab. YMMV if you have insulation underneath.

Thank you for all your comments. I am trying to make a decision without being overly swayed by the monetary aspect. That's difficult considering how much we would be saving lol!

This "sweating" y'all mentioned, how extreme was it? Like get out mop wet?

For me, when the sweating occurred, which was so rare, it was definitely enough that someone could've mopped it up. I would just let it dry out over night though; for me it never lasted more than part of a day. I'd be curious if the other posters with sweating problems had insulated or uninsulated slabs.

Any relavence to his claims of cooler in the summer and warmer in the winter do to the sun warming the entire slab?

What type of windows will you be having? If you have LowE windows, then they will not be warming the slab.

Is he planning on having the patio part of the building envelope? If so, won't you have to worry about thermal bridging?

I think sweating slabs are the result of two bigger problems. The insulation thing and elevated interior humidity. If it's condensing there, it might be happening in more hidden places.

The orthopedic concerns are more interesting to me. I've been on the look out for studies and research but have yet to see anything definitive. I think orthopedic insoles are the answer to this concern and always wear them even in my old house with very "bouncy" wood floors. Carpet with thick padding is the only floor finish I can notice any substantial difference, and I wouldnt dare put that crap in my house.

I concur w dekeobee on EE. Without passive solar aspects, it's probably not a big deal but there are certainly minor energy advantages to having thermal mass inside the conditioned space.

Remember that all basements have slabs and I almost always prefer a stemwall slab to a crawlspace, mainly to avoid the indoor air quality concerns that come from building a cave directly below the living space.

We are meeting with this GC at the site tomorrow and I will ask about all the points raised above.

Thank you all.

there is an energy savings in having exposed concrete
floors, but it is thermal mass. has little to do with windows
warming slab, but the hvac system.
once the mass is heated or cooled, it will help to
hold the temp in the room.
this applies only to interior spaces of course.
if you have ceramic tile or some stone/slate
finish it still is interior mass. it is the wood & carpet
that insulate the slab floor keeping it from being
thermal mass.

I've seen some beautiful local stained concrete
floors. some with big cracks. to me the cracks
are a part of the beauty of the floor, within reason of course.

best of luck

Just for fun, here is a photo of our stained patio viewed from an upper deck. Our home is on a slab. Growing up, we had a crawl space. Only con I know of was the critters that would get under there.

I think that with a properly conditioned environment, the floors shouldn't sweat. In FL, we like to open the windows when it warmed up after a cold snap. Coupled with the FL humidity, the floors would sweat, like a glass of ice water on a hot day. Either control the humidity, or the temperature of the slab, and the problem goes away.

As for the floor being hard on the body, ask a professional dancer. I seem to recall a new auditorium being built years ago, and the professional dance troupe refused to dance on the concrete stage until they put a sprung floor over it. I don't dance, but I know from personal experience that I prefer the give of a wood floor.

I was in a fairly poorly maintained home with 20 year old decorative stained concrete recently. Bear in mind that it's not if concrete cracks, it's when. So you have to be ok with that look (which I am). After that length of time with, I suspect, little maintenance by the owners, the floors looked a little raggedy and could have used some love.