Built Up Slab Question

stampcrete

I need some input on a slab that will be poured even with the top of the frost wall that I poured today. Originally there was going to be a crawl space with the slab down 3'. Now the guy wants me to pour the slab up to finish floor grade so he does not have to use floor joices etc. His existing house is a slab with no basement. So I plan on pouring the slab inside the frost walls to the top of the wall after backfilling, compacting etc. My question is should I put any rebar or any pegs into the wall before pouring or should wire be sufficient. This slab will be a subfloor so I dont want any settleing down the road. Any suggestions would be helpful. Thanks Kirk

POOLMANinCT

pics?

as rule of thumb I always use #3 sitting on piece of dampened block... never mesh

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stampcrete

Ill have to post some pics when I get some time. I need to put a order in for some steel for another job so Ill figure in some extra for this job. I dont do many jobs that require extra reinforcement besides outside flat work that has no structural importance or a step down frost wall where I might put a rebar or two in . Thanks- Kirk

mainer1

If you had known a head of time the best thing to is to run a 2x4 brick ledger around the inside. I would definatly bore 1/2" pegs a lest every 2' and with laterial tieing them all together.

genecarp

pegs wont stop settling, its all about the tamping, if the the compaction is correct, how can slab settle?

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concretemasonry

I would not put in pegs or dowels, but just build it right as slab over compacted base. Just make sure you compact the soil with the right amount of moisture.

If you don't have the compacted soil suporting it, you have a structural slab that must be reiniforced more to span wall to wall when the undercompacted "dirt" under it settles.

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Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

mainer1

I skipped a step, yes you always want to to make sure everything is compacted to your best ablity. But all it takes is for that soil to settle 1/8" and the floor to fallow. If the Finish floor is tile what do you think is going to happen around the perimeter where the wall meets the floor, CRACK.....

genecarp

properly compacted soil should not settle 1/8", if it did the entire area should not settle, but only a couple of spots, the wire in the slab, in addition to a good mix, should keep the slab suspended as one piece, additionally, some cracking along the side walls is normal, just due to different materials meeting, base moulding helps with this. i have never pinned the slab to the found wall, and have never had a problem,

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DBCoop

Kirk,you are getting some good imput and I,ll throw in my 2 cents.On an inside the wall pour I do not dowel rebar between wall and slab.As stated before;compaction is the KEY! In my area the native soil sometimes has too high of a clay content to use as base.When that is the case I compact base rock in lifts and top off with about an inch of 3/4 minus.Moisture content is crucial,now i screed off and plate compact.I then thicken any load bearing locations to appropriate size and install appropriate bar.I,m guessing this a 4 inch pour,if so I install #3 bar on 2 foot center resting on 1 inch dobies.I then attach 1/4 inch closed cell foam to the wall with the top of the foam being slab elevation.The foam isolates the wall from the slab and and allows for movement between the two.

genecarp

coop, i like the foam idea

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