Concrete between floors?

I'm in the process of designing my new home in Florida.

I'd really like a walk out basement but I hate the sound of upstairs people clomping around.  I couldn't find a way to soundproof an upstairs floor so I got to thinking about somehow pouring a slab but how do you support that?  I can't find anything on the internet but maybe I'm using the wrong terms.

I understand real basements aren't a thing in Florida but I'm going to start at ground level with the basement and then build the soil up around it.  From the front it will look like a regular home on a large hill and the walk out will open out to the rear so you'll have a view of the new pond I'll dig to get the soil needed.

Most commercial building have poured in place slabs for floors. It's a known process. 

I would imagine it's expensive compared to traditional residential construction.

Rock wool insulation, no hardwood floor upstairs.

I've been hit with videos of poured floors collapsing during construction lately, for some reason.  If you do it, make sure you pay a pro...

Many houses here have a poured slabs for second stories. 

Use block on both stories as well. Older houses use block on the first floor walls and wood frame upstairs, avoid that if possible. 

I've poured many many radiant heat floors using superlight concrete on upper floors. It's used for thermal mass more than sound deadening though and I couldn't tell you if it works as such.

Many apartment buildings use OSB base floor with an inch or so of concrete poured on top of it for fire-rating. It seems to help some with noise reduction as well. YMMV.

In reply to carguy123 :

I can't hear a thing upstairs or when I'm in the shop. The trick is get enough material between you and the  upstairs feet ( or whatever)  I have at least 3&1/2 inches of wood, hardwood.  The main floor I have 4 inches.   
     You can't afford to buy wood at retail prices to do that so you have to get creative. I buy mine direct from the sawmill. There are a minimum of 9 people between the sawmill and you each doing something, adding their costs and markup. 
     If you buy direct from the sawmill you can cut out those points of markup and you will be able to buy for 25 cents on the dollar. Pick the right wood and it's even more.  
Now it's affordable.  So what's the right wood you ask?   It's the odd wood he doesn't have a buyer for.  In my case it was ash, box elder, elm, and soft maple. He cut it into 2 inch thick boards for me ( 6 inch wide 8 inch wide 10, 12, and 14 inch wide. ) those are actual sizes. Not the 1&1/2 wide "finished sizes".      My joists were 12 inches on center. So I was sure nobody would fall through even the lowest rated wood. Beside I put 3/4 inch thick plywood on top. Then the finished hardwood flooring on top of those.  
     By the way the 2" hardwood planks were cheaper than sheetrock on a per bd ft basis. 
Then put some rigid foam underneath.  

OK they have lightweight concrete, who knew?  Antihero was the concrete you poured over OSB?

I hate pier and beam houses because I can hear someone getting out of bed at the other end of the house and I have 2 stories right now with thick OSB tongue and groove floor over joists that are over 18" thick and I still hear the "drum" of footsteps upstairs.

If you did pour the ceiling/floor out of concrete how do you contain it to the pour and what does it take to support it.  I've seen all kinds of older construction where you can see the wood planks that were used as the framework for the pour.  Am I going to lose all kinds of space "downstairs" with massive supports?

Multiple layers of wood maybe with foam sandwiched in between like frenchyd suggests might also be an option.

The concrete is attractive over wood since this will be right on the water and hurricanes.

Where in FL are you moving to? Welcome to the state in advance!

While you're not putting in a music studio, there's more info here than can be learned quickly. http://johnlsayers.com/phpBB2/viewforum.php?f=2

Out on Key Biscayne off of Miami most new homes are all multi-story poured concrete floored homes.  It makes for a hugely tidy bill.  Cost per square foot goes sky high.    It takes as much wood to frame it all up for the pours, as it does to build a stick frame home.  But, most of those structures fall in the 2 to 7 Mil $ range.  

I would build a standard wood floor system, then after all wiring and mechanical systems are in place shoot in about 4" of closed cell foam.

OBTW, I built my first earth bermed home in North Florida in 1980.  It is still is dry and mold free, but it required a lot of research and good systems installed on those dirt bearing walls to be successful.  Places that get 180 inches of rain each year require special care.

carguy123 said:

OK they have lightweight concrete, who knew?  Antihero was the concrete you poured over OSB?

I hate pier and beam houses because I can hear someone getting out of bed at the other end of the house and I have 2 stories right now with thick OSB tongue and groove floor over joists that are over 18" thick and I still hear the "drum" of footsteps upstairs.

If you did pour the ceiling/floor out of concrete how do you contain it to the pour and what does it take to support it.  I've seen all kinds of older construction where you can see the wood planks that were used as the framework for the pour.  Am I going to lose all kinds of space "downstairs" with massive supports?

Multiple layers of wood maybe with foam sandwiched in between like frenchyd suggests might also be an option.

The concrete is attractive over wood since this will be right on the water and hurricanes.

You can't let concrete touch wood, and definitely not OSB. The floor has to be sealed from water going anywhere. It's usually poured 1.5 inches thick and has more in common with mortar than concrete with some mixes.

You would have to build up the floor but how much depends on the mix you choose and what the end goal is. The best answer I can give you is that it depends. Contacting your local concrete plant and ask them what they use for a mix. Regular concrete weighs 4000lbs a cubic yard give or take. That's roughly 200sq ft at 1.5 inches thick

carguy123 said:

OK they have lightweight concrete, who knew?  Antihero was the concrete you poured over OSB?
 

You might be able to do something with foamed concrete.  

https://www.hunker.com/12000912/how-to-make-concrete-foam

https://www.domegaia.com/how-to-make-aircrete.html

https://www.domegaia.com/store/c4/Tools_%26_Equipment.html

Can’t you just use  pre-stressed concrete panels to make the floor?  

EUREKA!!

A pair of overseas containers for the basement and then I have a strong enough structure to pour the concrete over it!  The stairs down to it are built out of block and enter from one end. 

Now to figure out how rustproof them

In reply to dyintorace (Forum Supporter) :

The Panhandle.  We really wanted to go further south but too many Northerners there and, it makes it too hard for the kids and grands to come visit.

I was born in Fla and my wife and I lived there in the 70's and I learned to talk when I drive.  The snow birds would come down for the winter adn they'd never driven in their lives and simply had no reference points for how fast/slow they were going and at what speeds to take a corner.  I blame public transportation for that.

You'd learn to talk them around corners and out of the fast lane

In reply to Honsch :

But I am putting in a karaoke studio.  Going to supplement my income by doing karaoke gigs

Purple Frog (Forum Supporter) said:

Out on Key Biscayne off of Miami most new homes are all multi-story poured concrete floored homes.  It makes for a hugely tidy bill.  Cost per square foot goes sky high.    It takes as much wood to frame it all up for the pours, as it does to build a stick frame home.  But, most of those structures fall in the 2 to 7 Mil $ range.  

I would build a standard wood floor system, then after all wiring and mechanical systems are in place shoot in about 4" of closed cell foam.

OBTW, I built my first earth bermed home in North Florida in 1980.  It is still is dry and mold free, but it required a lot of research and good systems installed on those dirt bearing walls to be successful.  Places that get 180 inches of rain each year require special care.

Any tips on what those systems are?  I intend to put a LOT of dirt to make it appear that the Top story is all there is and to make mowing easy without too steep of a hill. 

The panhandle isn't totally flat like most of the peninsula. You may be able to find a hill to work with.

In reply to Floating Doc (Forum Supporter) :

What he said.  From about Panama City on west you don't get too many hills, but east of that you can get plenty.  I grew up in Tallahassee and I knew plenty of houses built the way OP is describing.

I started with large concrete footers with iron.  The walls were 12" wide concrete blocks poured solid with concrete.  Vertical rebar every 32".  About every 20' along the rear wall we built buttress walls out of block poured with concrete to handle the horizontal load of 8 feet of possibly wet soil pressing inward.

Then there were impressive french drains all the way around dumping down the hill down around the footers, and lots and lots of layers of waterproofing on outside of walls.  

The drains were covered with fiberglass cloth, then a layer of gravel, then another layer of cloth, then a layer of white sand, then the top soil.  The roof had 6' commercial gutters carrying water away from the berm.  Rome was not built in one day.

That structure was easily strong enough to support two more stories (which we didn't do).

carguy123 said:

OK they have lightweight concrete, who knew?  Antihero was the concrete you poured over OSB?

I hate pier and beam houses because I can hear someone getting out of bed at the other end of the house and I have 2 stories right now with thick OSB tongue and groove floor over joists that are over 18" thick and I still hear the "drum" of footsteps upstairs.

If you did pour the ceiling/floor out of concrete how do you contain it to the pour and what does it take to support it.  I've seen all kinds of older construction where you can see the wood planks that were used as the framework for the pour.  Am I going to lose all kinds of space "downstairs" with massive supports?

Multiple layers of wood maybe with foam sandwiched in between like frenchyd suggests might also be an option.

The concrete is attractive over wood since this will be right on the water and hurricanes.

Car guy is right,  spray foam would be easier but it's also many times more expensive.  Plus since I did nearly everything myself I would have had to schedule a contractor to come in and wait on his schedule. That and give him a clear floor.  
    Once I had a roof on I stored all my wood inside on the floor it would wind up being used. Like a professional I had access to free new Telehandlers to pick up wood and move it around to where it would be used. I just moved my tools and equipment  rather than all that wood.   

You can't pour concrete over a wood floor. Even lightweight concrete. 
 

You also won't get a building official to approve a concrete slab supported by shipping containers. No way, no how. That idea is cringe worthy to me. 
 

Those would both be engineered systems that would have to be designed by an engineer. 
 

Concrete floors are routinely done in commercial structures. They are typically supported by bar joists.  Again, engineering is involved. And the cost is huge- probably 10X the cost of a wood floor. Additionally, there are LOTS of construction details involved in properly pouring an elevated slab- most residential contractors are not familiar with the techniques (expect a lot of cracks)

Its pretty easy to make a wood floor that is sound resistant. First thing is to increase the thickness of the decking (plywood). A satisfactory floor can structurally be built with 3/4" decking. I recommend at least 1 1/2" for sound deadening. This increases the weight, which also increases the size of the floor joists. After that, consider an underlayment material such as Homosote. It's a sheet material made of compressed newspapers. It's a great sound insulator. Add finished flooring on top. Carpet is better than hard surfaces.  Use a good pad.
 

Under that, add batt insulation in the floor system. Adds density and mass. 
 

Then on the bottom side, don't apply drywall or other finished ceiling materials directly to the wood joists. Use metal Z purlins you give space separation between the drywall and the wood cavities (to avoid the echo "drum" effect). Lastly, consider 5/8" drywall- it's heavier and denser than 1/2". 
 

A system like this would probably cost 1.5X- 2X the cost of a standard wood flooring system. Much cheaper than concrete. 
 

Good luck!

carguy123 said:

In reply to dyintorace (Forum Supporter) :

The Panhandle.  We really wanted to go further south but too many Northerners there and, it makes it too hard for the kids and grands to come visit.

I was born in Fla and my wife and I lived there in the 70's and I learned to talk when I drive.  The snow birds would come down for the winter adn they'd never driven in their lives and simply had no reference points for how fast/slow they were going and at what speeds to take a corner.  I blame public transportation for that.

You'd learn to talk them around corners and out of the fast lane

 

I think you're stereotyping everybody from northern climates.  While your statement is probably valid for those from Northern Urban areas with great mass transit systems.  Most of us from more rural states drive extensively all our lives.
 Yes I drive extensively in bumper to bumper rush hour traffic so am used to remaining alert and staying with the flow of traffic. I see that same trait in even much older drivers. Little old ladies peering underneath the steering wheel over in the right lane keeping up with the flow. 
      Now the real farmers who rarely drive in urban environment may be frightened and drive in their  own world may be as you say.  But their numbers are few.  Most remain in the area they grew up in. 

In reply to SVreX (Forum Supporter) :

I agree on the shipping container idea, that's a horrible idea. Concrete is really heavy, I sure as hell wouldn't want to be in a shipping container covered in concrete.

But you absolutely can pour concrete over a wood floor, it just has to have a barrier so it doesn't actually touch the wood. It's used in radiant heat floors a lot and it's very popular in colder climates. It does require the floor being beefed up because even lightweight concrete is heavy. It's basically thermal mass and not usually finished either. I'm not a fan of it myself