Concrete slab or footer?

[Nicholas Iascone]

In a new and being constructed home that has required footers, also have footers in the middle of basement to hold posts. My question is: Can the concrete slab be poured first and THEN build the posts and bearing walls on top of the the slab over footers or do I have to build right to the footer.

Also there is a large front porch that is going to be concrete slab but is also serving as a safety room ceiling below, can the brick on the front porch start at the slab or does it have to start at footer/brick ledge and pour slab after brick is installed? Just not quite sure of sequence order

Thanks for any help!

[John Kogel]

Set the posts and walls right on the footers.

What you 'have to' do depends on the authority in your area, if you have one. But standard practice is usually the best. Pour all your footings. Pour the slab up to the footings. Expect shrinkage and cracking where the slab meets the footings.
Slab and footings can be done together in one pour, but since you are asking here, go the conventional route that is proven.

[Garry Sorrells]

Typically a footer should be resting on undisturbed earth.
Typically a slab is not pored on undisturbed earth but over stone, sand an other materials.
Footers and slab can be pored as a monolith pore depending local codes.
At times the foundation wall must be tied to the footers using rebar.
Typically the wall plat has to be bolted to the slab.

Helps I hope. Though I may be seeing an elephant in your description of a camel.

Go to local permit/inspection office and they should be able to answer your code question.

[H.G. Watson, Sr.]

I can only guess, but is the reference to a "safety room" under the "porch slab" is a storm shelter from the regular tornados through the area?

NWS LIncoln County TN Tornado Sort (http://www.srh.noaa.gov/hun/?n=lincolntntor)

Not even sure what you're actually asking about, since so much is ambiguously undefined, such as what kind of slab ...topography...geography, ...what's being built, etc.

Most should be available with geo tech & stamped plans from lic. des. pro.

[Jim Luttrall]

Unless you have a monolithic slab (rare) the slab needs isolation joints around piers and the footers. The slab needs to be able to move freely due to the different attributes of the different types of bearing.

[Billy Stephens]

Unless you have a monolithic slab (rare) .
Most Common used in New Construction ( past 40 years ) in my area.
* but we also have some old crawls and a very few ( pre 1920's ) basements.

[Jim Luttrall]

Most Common used in New Construction ( past 40 years ) in my area.
* but we also have some old crawls and a very few ( pre 1920's ) basements.

Yes, 99 % of what I see but then we don't have many basements.
I would suspect a monolithic slab poured with the basement walls would be a rare creature indeed.

[Billy Stephens]

I would suspect a monolithic slab poured with the basement walls would be a rare creature indeed.
Got it. :D
Poured Basement floor is not a foundation slab, it's just a floor.

[Door Guy]

Yes, you can pour the basement floor on top of the footing pads already poured. Nothing wrong with that. You will need to fasten the posts to the floor and your beam.
The porch can also be poured first as long as the concrete extends directly on the brick ledge. The only problem could arise would be if something happen to the porch slab. You would also need to remove the brick to pour a new porch. Don't forget to flash on top of the porch and under the brick. We always used a rubber roofing membrane under the slab when a room is below.

[Thom Huggett]

I recommend that the building be designed, or at least reviewed, by a Registered Civil/Structural Engineer, especially with free spanning concrete slabs and masonry/brick walls. The Engineer should also field inspect for proper construction.