# Concrete slab! Before or after the Walls! That is the question!



## ront02769 (Nov 28, 2008)

Where I am, no one pours the floor before the basement walls. And no one uses footers anymore. It is normally a single pour for residential with a foundation wall wide enough to serve as footer. Separate footers were a must when basement walls were block but much of that around here has been replaced by forms and single pour concrete. Ron
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## Canarywood1 (May 5, 2012)

GPC said:


> Ok. new here and hope I don't get flamed for anything.
> 
> We will be starting a new home construction in the next 8 months and the wife and I are learning all we can.
> 
> ...


 


Basement floors are usually poured last, that is after the roof is on.


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## JT Wood (May 14, 2014)

ront02769 said:


> Where I am, no one pours the floor before the basement walls. And no one uses footers anymore. It is normally a single pour for residential with a foundation wall wide enough to serve as footer. Separate footers were a must when basement walls were block but much of that around here has been replaced by forms and single pour concrete. Ron
> .


That must be a regional thing, We have a separate pour for footings,
Walls then slab.



The slab is done after framing and roofing. (at least here.)


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## TheEplumber (Jul 20, 2010)

OP didn't mention a basement- could be slab on grade home.

Perhaps the house was started during cold or rainy weather and they opted to proceed without the slab. I've seen it done, especially in commercial construction.


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## concretemasonry (Oct 10, 2006)

GPC -

Building upward is always necessary, but often it is just for the bones (structure) that are the footings, walls, a cap for the area for the nail benders to build on, trusses and roof to make it possible to work on the interior under reasonable conditions.

Local weather conditions, such as unpredictable rain storms or the "good old" reliable cold weather will dictate some differences in the importance of the steps. Here (4'+ of frost and big, short rain storms), where we have basements, in the winter, a basement foundation is usually done and ready for capping (excavation and walls)in a week. The furnace is "hung" in the basement area to provide heat for the nail benders working above to get the roof on. The basement floor is done much later and usually about the same time as the sidewalks and garage slab since they are not on the critical time path for the variable climate.

Dick


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## Msradell (Sep 1, 2011)

ront02769 said:


> Where I am, no one pours the floor before the basement walls. And no one uses footers anymore. It is normally a single pour for residential with a foundation wall wide enough to serve as footer. Separate footers were a must when basement walls were block but much of that around here has been replaced by forms and single pour concrete. Ron
> .


What kind of soil do you have in your area? I've never seen basement walls thick enough that it would work as a foundation. Around here they always do footers 1st, then pour the walls on top of them. The wall thickness certainly doesn't have enough bearing area to support the entire weight of the house. Basement floors are kind of poured whenever. They are normally done quite early in the process however to allow space for setting the HVAC system, water heater etc.


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## concretemasonry (Oct 10, 2006)

Msradell -

A basement wall is a part of the foundation. The vertical load from the weight of the house and loads are far below the capacity of a wall as thin as 6". The problem for a basement is the lateral loads from the soil that just require some reinforcing steel in the block or concrete. Some of the commonly used ICF foundations have a concrete core inside of the foam that is only about 6" thick, but obviously has reinforcing steel. Using block or concrete, an 8" wall can be used for 9' ceilings, but 10" or 12" thick walls are usually cheaper.

Dick


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## Nailbags (Feb 1, 2012)

Out west we do what is called a Monolithic foundation it is the footings and stem wall all in one pour. Back fill the garage and pour the cement after the house is dried in. some times the slab will be poured for a home after it is dried in and the plumbing is done. Then the cement slab is done you don't want the rain to leave dimples in the cement floor.


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## GPC (May 14, 2014)

Wow thanks for the great replies.

This house is going to be built in Cancun Mexico. The gorund is Rock. Basically almost on the bedrock. 

Here a Basement is a swimming pool.  So no basement.

I have also seen many Commercial buildings done this way where the buidling is completed and being sold but inside you can see dirt instead of concrete. 

Since I am from Florida I have always seen the footers put down, then the slab ( Floor ) poured and then the walls go up etc. 

Is there a draw back or Benefit to pouring the floors last?


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## MTN REMODEL LLC (Sep 11, 2010)

Here in Colorado, normal foundation is a spread T footer @12", then 8" stemwalls, then slab. (Not sure eng wise, but I think the T footer has as much to do with frost heave as with soil bearing... we're on decompoed granite)

As contrast in Cali, we just poured the stem walls without any footer. One time we did the stemwalls with a rebar tied in SOG in two pours (which yioels a cold joint).... other time we did a mono-pour.... stem walls and slab in one pour)..... also noticed alot of post-stressed slabs going in with the production builders.

*I'm no engineer,* but in an escavated foundation (basement), I would think the slab would have a structural importance with regard to lateral loads when the site is backfilled..... with SOG... not so.

I might think that locating plumbing under slab might be easier with foundation perimeter set, but I don't understand the advantage of pouring it after closed in... seems if anything pouring as soon as possible would be beneficial for ease of concrete delivery and neatness of subsequent build up.?????

I wonder also what the advantage of pouring last would be??????

Best


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## landfillwizard (Feb 21, 2014)

Normally a concrete floor is poured after the roof is on. This keep weather elements from ruining the floor finish. His house is being built in Mexico, the contractor may want to keep the sun off the floor so the concrete won't dry too quickly.


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## MTN REMODEL LLC (Sep 11, 2010)

landfillwizard said:


> Normally a concrete floor is poured after the roof is on. This keep weather elements from ruining the floor finish. His house is being built in Mexico, the contractor may want to keep the sun off the floor so the concrete won't dry too quickly.


Possibly.... but sure seems a surface curing sealer or plastic would be easier....... if rain is an issue, seems you could easily find 6 hours without rain and would not want the mud involved in build up untill you're topped.


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## ront02769 (Nov 28, 2008)

Msradell said:


> What kind of soil do you have in your area? I've never seen basement walls thick enough that it would work as a foundation. Around here they always do footers 1st, then pour the walls on top of them. The wall thickness certainly doesn't have enough bearing area to support the entire weight of the house. Basement floors are kind of poured whenever. They are normally done quite early in the process however to allow space for setting the HVAC system, water heater etc.


I am in SE Mass and am typing this in my living room......which sits on a poured concrete foundation 10" thick, no footings, single pour. Three houses down the street just built same. Habitat house I am working on same. Perhaps it is regional. But trust me when I tell you that a 10" foundation wall will hold a house.

Ron


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## Msradell (Sep 1, 2011)

ront02769 said:


> I am in SE Mass and am typing this in my living room......which sits on a poured concrete foundation 10" thick, no footings, single pour. Three houses down the street just built same. Habitat house I am working on same. Perhaps it is regional. But trust me when I tell you that a 10" foundation wall will hold a house.
> 
> Ron


As I said, it depends on the soil conditions. So your home has 10" thick walls sitting directly on dirt with a slab poured at a later time between the walls? I'm assuming the framing for the 1st floor is standard lumber, correct?


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## jomama45 (Nov 13, 2008)

MTN REMODEL LLC said:


> Here in Colorado, normal foundation is a spread T footer @12", then 8" stemwalls, then slab. (Not sure eng wise, but I think the T footer has as much to do with frost heave as with soil bearing... we're on decompoed granite)
> 
> As contrast in Cali, we just poured the stem walls without any footer. One time we did the stemwalls with a rebar tied in SOG in two pours (which yioels a cold joint).... other time we did a mono-pour.... stem walls and slab in one pour)..... also noticed alot of post-stressed slabs going in with the production builders.
> 
> ...


The benefit is that we can sit in a dark basement and drink beer without anyone seeing us, and it stays cooler longer........:drink:

Actually, there's a number of reasons. 

The original is that it allowed us to work on crappy/marginal weather days. 

It also keeps the chance of damage to the slab lower, as often the concrete slab is the finished product. Could you imagine if all hardwood flooring was set at the same time as shingles, and all the abouse it would take from subsequent trades?

Generally, we like to come in and complete all the flatwork at once, including the basement & garage floors, as well as any footed stoops. If the "nailbenders" don't have the deck on on the first floor, the stoop and garage steps are hard to form. And EVERY carpenter complains if they have to frame the skirt behind concrete.

Lastly, most of our basements are braced until the floor is poured. When we set the floor up, we have to take the bracing out. Waiting allows the backfill to settle and there's less chance on creatign damage to the foundation via Skytrak's., etc.....



ront02769 said:


> I am in SE Mass and am typing this in my living room......which sits on a poured concrete foundation 10" thick, no footings, single pour. Three houses down the street just built same. Habitat house I am working on same. Perhaps it is regional. But trust me when I tell you that a 10" foundation wall will hold a house.
> 
> Ron


I've been around this stuff a long time, and I've never heard of poured walls for a basement resting on soil. Just way too many potential problems to save a little money and maybe a day on the schedule. ANy chance you have a architectural drawing, or even pictures, on how they do this? The form setters must complain to high heaven if the excavator is off by more than an 1/8" in elevation.........


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## stuart45 (Jun 20, 2009)

jomama45 said:


> The benefit is that we can sit in a dark basement and drink beer without anyone seeing us, and it stays cooler longer........:drink:


That's a good enough reason for me Joe.


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