I have been doing the resurch on foundations and I was wondering what the addvantage/disadvantage is to pouring a monolitic foundation is? I will be usisng an ICF product for the wall construction on this job. After the wall and floor are poured I will continue up with the ICF wall system up to the top plate for the roof. With a monolitic foundation, will the cracks in the floor be much greater than in pouring a floating basement slab. Due the the fact that the floor does not have any place to move.
Thanks,
J.K.
Replies
I don't know what you mean by monolithic or that it won't have room to move.
You would be pouring them at different times or your concrete would all run out of the icf forms and the icf form will also be your expansion joint material.
Please clarify
Gabe
I'll take a guess at what's meant and maybe you can apply the industry standard terms to it (and I know I'm not saying anything you haven't come across a thousand more times than I have). If someone said monolithic slab to me, I'd think the footers and the slab were formed and poured at the same time. Slab with integral footer. It's occasionally done with smaller domes as a convenience. If the slab is poured subsequent to the footers and walls, then it won't typically be structurally connected to those elements, and if expansion joint material is used, has the ability to expand/contract independent of the footer.
Could this be what he means, and what are the best terms for describing it?
It's normally a combination pour. Walls and deck. Footing and column. Slab and footings. but it normally also includes a delay in pouring the second component to allow setup of the concrete.
If he meant the slab and walls, it would be very wrong to try.
Gabe
>combination pour
Thanks.
I've never seen a basement slab and perimeter footing poured at the same time where all foundation walls are below grade. I have seen walk out basements with monolithic slabs butting to foundation walls on strip footings. I have never seen masonry or concrete foundation walls supported by monoligthic slabs, nor have I seen this addressed in any code book. I have not seen any more or less cracking on monolithic slabs when compared to slabs on grade.
My greatest concern for this method would be the horizontal thrust of the earth on the wall at the base. What would you use to stop the wall from sliding along on the slab? A couple pieces of rebar might not do it. If you pour the footers, then the walls, and place the slab to the inside of the walls, it acts ass a kicker against this pressure.
The cracking you consider would be more a factor of the soil preparation ahead of time. Poorly compacted organic soils will allow more movement under the foundation. I fyou build on a sponge, expect to squeeze the water out. You need undisturbed hard bottom or add in 8-10" of compacted inch minus or other stoney boney material.
piffin, whenever we use monolithic slabs, or simple footers, for that matter, we always include a keyway. Of course, we're also spacing the vertical rebar at 12", so there's a fair amt of it.
The consept for this floor came from the Fine Home building June/July 2000 page 88. I have seen other builders construct this type of floor, but I am consernd about the fact that yes the ground and the concrete do move at diffrent rates. I was wondering if the rebar in the floor is enough to stop the cracking that typicaly happens in a basement floor. I am sure that there are many other consern that I have not mentiond.
Hi Legs,
I am widely experienced in concrete foundations,engineering, and applications on the commercial level. However, I have yet to pour a monolithic slab-on-grade/foundation wall.It is more common to pour an elevated slab/paraphet wall combination. The building codes in my area(AL)dictate the application of pilasters in such a pour,of course their locations & sizes depend on your area and load bearing specs.It is a great idea, and not at all inpractical , or difficult to apply by an experienced contractor. Best wishes, and good luck.
"I was wondering if the rebar in the floor is enough to stop the cracking that typicaly happens in a basement floor."
Absolutely not!!!!!!!!!!!!!!!
Gabe
I just noticed the address on this post. This was meant for Legs....
Edited 4/19/2002 2:47:50 PM ET by GABE_MARTEL