Grade beams in garage floor


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Old 09-29-03, 02:35 PM
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Grade beams in garage floor

I am trying to find information about grade beams for the slab in a 3 car garage. The garage is 30'x30' and the footers and walls are in place. I know I read an article about the floor and grade beams but cannot now find it. Is there somewhere to go for detailed information about how many are needed, sizing and reinforcing needed?
Appreciate any help.
 
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Old 09-30-03, 08:07 PM
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Can you be more specific about your request?
Are you talking about the thicked concrete area under your walls?
Like footings?
What's the reason to be asking now if the walls are already up?

Curious?
 
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Old 10-02-03, 05:57 AM
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I am referring to a thickened area that runs under the slab. It would be similar to footings under a wall, but the purpose is to provide additional support, especially in an area where heavy objects (such as a car) will be placed/travel. The one place I have heard of them used, in particular, would be for a slab on grade house when there is a load bearing wall near the middle of the slab.
 
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Old 10-02-03, 07:30 AM
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True, this would be used for load bearing walls but this is usually in cases where there is a 2 story structure above it, where the loads transfer from the second floor down to lower level of a basement per say. Most homes have steel beams and posts so the thickened areas (footing application as you describe) is not required. In a garage, this is not necessary. Usually 4" garage slab that has proper size footings or if the garage slab is to be a single pour - monolithic pour with a 4" garage slab/wire wire mesh is more than sufficient. This has alot to do with proper substrate - good sand base, compaction and existing soil conditions.

Hope this helps!
 
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Old 10-04-03, 05:48 AM
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"Usually 4" garage slab that has proper size footings or if the garage slab is to be a single pour - monolithic pour with a 4" garage slab/wire wire mesh is more than sufficient. "

Here's the layout--we've got good soil although we did have to backfill about four foot in general and 8 foot inside next to the foundation wall; the slab is being poured independently of the walls and will be 4". I guess what I need is the 'footings'. I know on a monolithic pour the footings are poured around the perimeter of and in conjunction with the slab. I'm concerned that with such a large slab--about 32x29--I want/need support for the interior portion of the slab especially because I do have so much backfill and, even with compacting, there will/may be some settling.
 
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Old 10-04-03, 06:00 AM
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Sounds like you would need additional footings and/or additional grade beams, if you will, if there is that much backfill needed. If you don't, you are correct that in time, there may be a void developing under the slab, thus, cracking would occur.

Issue is to provide good sand base fill prior to pouring concrete.

Thanks for filling in the rest of the story!

Good Luck!
 
 

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