Foundation slab - queries and good practices...

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Folks -
Well, yesterday I put in another drip system for the half barrel planters along the West fence line and removed the remaining debris that was where the pad will be poured. I have a *load of scrap, piled on a 4x8 table, and then some, and getting that sorted out will be a trick. I have TONS of off cuts and scrap and hate to part with ANY of it.
So, for the foundation... I have ....questions..... Now, this is a 24x36 Covered Patio - the North Side is a solid wall and it is open to the South. The East wall abuts the garage, the foundation is tied to the garage slab and the roof peak meets at the peak of the garage roof. The entry to the patio is from the garage, in the Southeast corner.
The plan calls for the foundation to be level with the garage slab, approximately 14" above grade. The foundation has perimeter footings, 16" wide and 12" tall, a minimum of 6" below grade, adjoining a thickened edge for the 4" (min) slab and 2x6 walls.
Based on my calcs, I am going to need just under a foot of fill - so ~864 CF or about 32 yards. If I use rock for fill, it will come to just over 800 bucks. I don't know how much fill dirt is or which is the better way to go. That seems expensive, but how often do I buy rocks? I was planning on renting a compactor....
Is a 4" thick slab going to be enough? Is 6" silly? I have/will have most of the regular tooling... the heaviest thing I could imagine I'd own would be a 15" planer or other old iron... 1,000 - 1,500 max. How much do I need?
Like everything else, I have to balance cost/benefit to the nth... so....
My estimates for Aggregates is $3,478, Foundation Mat'ls at 1,617- ... and equipment rental and "handholding" oversight are 672... So it's just a notch under 5 k for materials and my own work or about 5.78 per SF.
Tomorrow morning we are going to lay out the foundation lines for the backhoe guy. The footings extend 6" beyond the perimeter of the slab proper, and the fellow said to give him a chalkline 3" outside of that. So, I need to mark out 24'9"x 37'6" (24'+ 9" = 24'9" (one end only) by 36"x (9"x2) = 37'6") for him to work with.
I worked up an Excel Spreadsheet for these figures, and I can email it to anyone that would like to use it for their own projects. You can plug in your own numbers and it will factor the total yards and cost, and adjust totals... you can edit easily enough for your own porpoises as well.
Any feedback or cautionary tales will be deeply appreciated!
TIA
John Moorhead
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On Sun, 25 Jul 2004 18:55:09 GMT, "John Moorhead"

pay somebody with LOTS of experience to finish the slab. you won't regret it.
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On Sun, 25 Jul 2004 13:24:50 -0700, bridger wrote:

...and make sure they use the proper reinforciing mesh/fiber/whatevere and that they finish in control joints no more than 12' apart - in your case, scoring the slab into 6 roughly square sections. Also, make sure they seperate the slab and foundation walls with expansion joints so your slab doesn't expand and crack your foundation in hot weather.
-Doug
--
"If you have an apple and I have an apple and we exchange apples
then you and I will still each have one apple.
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John Moorhead wrote:

I got less than that for cubic yards. 24x36x14 cubic feet / 27=5.33 yards x $24 ( for class II base in my area, per yard ) = $128 . Fill dirt in my area is $5 a yard, so using your cubic yards of 32, fill dirt would cost you $160. http://www.ofwolfinbargerinc.com Or did I miss one of your numbers somewhere?
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New Math?? 24X36†4 on my calculator 864/272 ???

CF
go.
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Doh!! Maybe I hit the plus sign?!? Who knows what I did! Well, still, at 32 yards, $160 will get you fill dirt!
Wilson wrote:

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On Sun, 25 Jul 2004 18:55:09 GMT, "John Moorhead"
Snip

You'll need to put a dowel joint between the existing slab and the new one in order to keep the new and old slabs from shifting at the joint. It's nothing more than drilling horizontal holes in the side of the garage slab and putting in 1/2" smooth steel dowels about 18" long every 16" or so, half in the new slab, half in the old.
Snip>

The best base to use for a sub-base for a slab (IMO) is a gravel mix called 304. I'm not sure what the numbers represent, but it is a graded mixture from about 2" aggregate down to dust. After it is moistened, compacted and allowed to dry, you *may* not need a concrete slab, esp. at a foot of thickness. :)
On filling: the heavier the compactor, the larger lifts (amount you can put in before compacting again) you can get away with. For a 24x36, you can use a plate compactor (think push mower), but I wouldn't do a lift of more than about 3". This means wheel or bobcat a bunch of 304s in, rake them out, run the plate compactor for an hour or so (while sprinkling a bit with a hose), and doing it again. And again. You cannot possibly compact your sub base too much.

A 4", 3000 psi slab should be good. Go with 4000 psi if you're still worried--the cost should only differ by a few bucks a yard. Also, if you and your friends and neighbors plan to finish this yourself, get fiber mesh in the 'crete rather than fooling with wire mesh. The cost is about the same, but you save a lot of time and holes in your yellow boots by just getting the fiber mesh. Not to mention the fact that rolling out and cutting 6" wire mesh is pretty a hairy affair in itself.
Snip

I would hire at least one veteran concrete finisher, preferably one who does house slabs, to help keep from losing the 'crete. Explain to him what you want to do (a bunch of greenies on a weekend project--no offense intended), and ask if he's still willing to help. A lot of them probably won't due to the fact that concrete finishers can be pretty ornery while their slab is getting hard and it still needs some troweling.
As was mentioned, score your slab every 12' to help with cracking. The sooner the easier.
Additionally, I would power trowel (think gas-powered floor buffer) the slab smooth as a baby's ass and liberally apply a concrete curing and sealing agent, e.g. Cure 'N Seal as soon as you don't make footprints in the slab in your sock feet. Before that, if you have a method of delivery, like a high-pressure spray bottle. Install a drain, and slope your slab to it. Even if you just run the pipe out the side of the slab and never use it, it's much MUCH cheaper and easier to have it installed now.
As a confirmed believer in overkill, you may not need 304s, 4000 psi concrete, drains and dowel joints. But I would put them in my slab.

Good luck, John, and glad to help (if I did).
-Phil Crow
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Light broom finish rather than baby's butt smooth as suggested. Epoxy cured, clean slab to keep down cement dust. Sprinkle a little sand in the tacky epoxy for traction. YOU DO NOT want a slippery shop floor (DAMHIKT). Go with the lighters floor epoxy - more light reflected more light by which to see
charlie b
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I'm a stingy DIY guy, but around here we get slabs for about $3.50/SF. I'm not sure if that includes the footers, but I'd sure get some quotes before starting. Yes, you can do it, but it's no fun. 304 is nice, but gravel takes less packing. I like wire, maybe even with the fiber. Get the contractors rep aside and make it clear you want a reasonable price. Around here, they often bend the office rate to get jobs. Call around and you may find a hungry one. The concrete is pretty much a monoply, but sometimes you find a couple of unused or partial loads they will drop for you. I made a basketball area that way. Wilson

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Sun, Jul 25, 2004, 6:55pm (EDT+4) snipped-for-privacy@splinter.sbcglobal.net (John Moorhead) says: Folks - Well, yesterday I put in another drip system for the half barrel planters along the West fence line <snip>
Nothing illegal I trust?
this is a 24x36 <snip> My estimates for Aggregates is $3,478, <snip> So it's just a notch under 5 k for materials <snip>
Wow. What part of the country do you live in? A couple of years ago I priced a slab for a garage, about 22X32, and I was quoted either $1500 or $1600. That wa for the guy filling in at the back, as required, the labor, forms, reinforcement, fill, etc., and concrete (delivered by a ready mix company). Unfortuately, I wasn't able to do it at the time, but hope to later this year - at some extra cost, I'm sure, and after I get a loan. LOL I'm in central NC. Can't recall exactly how much concrete would be required, but the cost then was $672, as I recall, which was included in the $1500-1600 quote. I'm hoping for $2 K max, but not holding my breath, I still have to get quotes.
You might want to check with some small contractors, and get some quotes. If you still have time. I'm forced to pass on labor, because of my back, but even so, I think I'd probably still pass on it, if I could. I've done cement work in the past, and work is the operational word.
JOAT Expensive tennis shoes won't cure a sore toe. - Bazooka Joe THE NEW COPPERPLATE http://www.banjer.com/midi/newcopp.mid
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Nothing illegal I trust?
this is a 24x36 <snip> My estimates for Aggregates is $3,478, <snip> So it's just a notch under 5 k for materials <snip>
Wow. What part of the country do you live in? A couple of years ago I priced a slab for a garage, about 22X32, and I was quoted either $1500 or $1600. That wa for the guy filling in at the back, as required, the labor, forms, reinforcement, fill, etc., and concrete (delivered by a ready mix company). Unfortuately, I wasn't able to do it at the time, but hope to later this year - at some extra cost, I'm sure, and after I get a loan. LOL I'm in central NC. Can't recall exactly how much concrete would be required, but the cost then was $672, as I recall, which was included in the $1500-1600 quote. I'm hoping for $2 K max, but not holding my breath, I still have to get quotes.
You might want to check with some small contractors, and get some quotes. If you still have time. I'm forced to pass on labor, because of my back, but even so, I think I'd probably still pass on it, if I could. I've done cement work in the past, and work is the operational word.
Not sure how much concrete costs in the NC area, but I just had a garage slab done a few weeks ago...the week after the Fourth, that is...and part of the driveway. I had done the demolition of the old work and hauled it all away, then I got hurt, nothing serious, just serious enough to keep me from slinging mud...anyway...
24X26 garage slab, smooth troweled, wire mesh 3" of clean pea gravel and zip strips for crack control and a 10X26 piece of the driveway, all the same details except that it took about 4" of fill and was a brushed surface. It was under $2K...not by much, but some under.
And the best part for me was that they did it FAST...I called on Friday afternoon, dude came and looked at it on Saturday morning, deal was done over a handshake and the work was finished on Thursday.
Oh, for camparison, ready mix concrete, 3-11 yard load delivered with a ten minute per yard wait time included runs about $80/yd and clean pea gravel runs $10 a load. No idea what they get per yard on the gravel, because where I go charges by the load for homeowners, not the yard...and I have a friend with a dump truck.
Just for comparison and your mileage may vary.
Mike
JOAT Expensive tennis shoes won't cure a sore toe. - Bazooka Joe THE NEW COPPERPLATE http://www.banjer.com/midi/newcopp.mid
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The Davenports notes:

It may be different now. A friend just did a slab floor for a 20x20 shed: $80 a yard, and this is in central VA. Another friend, local chief building inspector, tells me there is a nearly world wide shortage because of some kind of dam construction in China. Most of the current production is going there. Predicted to last until, IIRC, 2007, so prices will keep rising. That means contractors get dibs (good, steady customers), while Joe or Jane Sixpack get to wait until there's some excess, whenever that might be. My friend got his right away. Maybe you will, too.
Charlie Self "I think the most un-American thing you can say is, 'You can't say that.'" Garrison Keillor
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On 27 Jul 2004 08:08:01 GMT, snipped-for-privacy@aol.comnotforme (Charlie Self) calmly ranted:

It's $80/y3 here, too, but it's over $120 a yard in LoCal. CA sand (real estate) never was cheap.

http://www.cnn.com/SPECIALS/1999/china.50/asian.superpower/three.gorges / It's a WHOPPER!

2009.
------------------------------------------------- - Clinton never - * Wondrous Website Design - EXhaled.- * http://www.diversify.com -------------------------------------------------
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Larry Jaques posts:

OK. Either way, it looks like a good reason to be glad you don't live anywhere near the inundation path...or the country it's in. They're doing it on a grand scale. One has to hope that some niggling goof-up isn't going to create a disaster on the same scale say a decade or two down the road.
Charlie Self "Did you know that the White House drug test is multiple choice?" Rush Limbaugh
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On 28 Jul 2004 08:42:56 GMT, snipped-for-privacy@aol.comnotforme (Charlie Self) wrote:

Rebar? what rebar....

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bridger responds:

Oh, man. You just made the skin on my back crawl.
A mile and a half wide. How high? Wonder what the final containment will be.
Charlie Self "Did you know that the White House drug test is multiple choice?" Rush Limbaugh
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1.4 trillion cu/ft according to the chinks
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more info:
http://www.cnn.com/SPECIALS/1999/china.50/asian.superpower/three.gorges /
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On 28 Jul 2004 08:42:56 GMT, snipped-for-privacy@aol.comnotforme (Charlie Self) calmly ranted:

Sadly, it's a beautiful area they're filling up.

Yeah, there are even more folks downstream which will be losing flow until the dam fills up, then are at risk if it breaks.
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John;
    I can barely tell, but do you have any bearing walls on this slab, or will you ever have any bearing walls on the slab ? If so, then the foundation, based upon where you live may not be sufficient. Usually the footing should be about 2x the width of the foundation wall, and that this wall needs to be at least as deep as the frost depth. This is where your location in the country should come into play. It also sounds as if your footing will be on fill or very close to the existing surface (i.e. the slab will be level with the garage slab minus 4" for the new slab, gives me 10" of fill. Then the foundation will be 12" deep, with a min of 6" below grade). This sounds as if the bottom of the foundation will be 2" below the existing ground surface. I do not believe you will have sufficient 'undisturbed' soil at this depth. I would suggest digging a little deeper and compacting the soil and placing 304 (interlocking gravel) for a couple of inches at this lower depth. Remember to compact this also. If you find soft spots at the bottom of the foundation ditch, you must go deeper, untill you find sufficiently stable soil. This will be areas where the 304 will also come in handy, to fill these irregularities (sp ?). Rememer, if you are going to do an excessive amount of fill with any material (304, siol, etc) that will later support loads, you need to place this in about 6" lifts and compact.
John Moorhead wrote:

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