We had our basement walls poured about 2 weeks ago and the builder is to begin basement slab pour on Thursday if no rain. When I was out visiting the site today, I noticed that the area underneath the walls that will support the first floor are cleared of gravel about 15 inches wide and the full length of the walls. I called the builder since I did not see rebar in this area and he told me that since the we were using a fiber mix concrete on undisturbed soil that the footing for the walls did not require rebar. House itself is 2800 sq. ft single story with a basement on clay soil. Last house we built was 25 years ago and had rebar, but then no fiber as far as I know. Any thoughts?
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What do the approved plans require?
The "areas cleared of gravel about 15" wide" are for footings or grade beams under the walls....I live in a seismic zone so we use a lot of steel in our foundations and footings....fiber is not a substitute for steel reinforcement....not around here anyway.
But then, the reinforcement should be spec'd on the plans.
call the bldg inspector now. code calls for three #5. fiber and rebar are not the same. fiber controls cracking, rebar controls load factors. you cannot replace with other.. 2+3=7
"since the we were using a fiber mix concrete . . . did not require rebar. "
Fiber and rebar don't compare. Apples and oranges. They have to distinctly different purposes in life.
What if he said, "Since we're putting insulation in the walls, we don't need studs," Would you buy that? It's basicaly the same statment.
However. . . sometimes, due to soil conditions, structural loads, and other design considerations, you don't need rebar.
If you accurately quoted him, he's either trying to baffle you with BS, or, he doesn't understand the different functions of rebar, WWM, or fiber.
In short, Rebar is a structural component placed in concrete; WWM (welded wire mesh) is to keep the agregate interlocked in the case of small cracks; Fiber is to keep the surface pretty, ie. helps-prevent small nonstructural cracks.
They are NOT interchangable. But all of them, to some extent, help to prevent cracking,
SamT
You have heard from our resident concrete experts. Your contractor needs to spend some time studying under them.
forget ever thing i wrote under before,finally got the pic. those are the footings running down the middle to support the 1st floor,gotcha. yes they need rebar under them. they are part of supporting structure. i would tommorrow meet with him and clear this up. your footings and walls have to have rebar,but the floor does not.if this gets screwed up you have nothing. i know a guy back in the 60's that as soon as the inspector would ok the rebar they would jerk it and put in in the house next door![tract houses-all were the same] you should see that 6 blks of house's now,cracks 1" wide in foundations.people buy there, live there a year and sell to the next guy,all so the builder could make a extra 25.00! larry
hand me the chainsaw, i need to trim the casing just a hair.
Edited 1/11/2006 12:36 am by alwaysoverbudget
Soil types and conditions are highly regional. The red clay we have here is extremely stable, and non-expansive. So, here, we don't use rebar in footings if they are dug down to undisturbed soil if the hard red clay is found. We sometimes use rebar in footings when it is specified by a soils engineer because the soil conditions are less than optimal. The soils engineer might specify two #5 or similar. Or He might specify to just dig 2' deeper and use no rebar.
The flavor of the IRC building code we use does not require rebar in footings except in seismic areas. Some counties in my state (NC) are considered seismic. Not only are the counties in which I build not considered seismic, but they are no where close to any that are.
All footings are inspected by the city or county where we are building. Our building inspectors (BIs) will never require rebar - they will require a soils engineer though. During the inspection process the BI probes the soil to see how hard it is, and if it is not to his liking he will reject it and require a soils engineer. After watching the BI inspection process a whole bunch of times I went out and got myself a probe rod. Now, I usually make the call for a soils engineer if necessary before the inspector gets there. Saves time and inspection fees.
That said, the stuff about rebar and fiber is as the others here said. Apples and oranges.
Edited 1/11/2006 6:57 am ET by Matt
Thanks for all the comments. I spoke to the builder today and rebar will be put down in the grade beams before pouring the slab. Thanks for the help.