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Old 07-27-2013, 10:58 AM
Janina5309 Janina5309 is offline
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Gravel Parking Pad into Concrete Driveway Contractor Question

So I had a contractor give me a quote on installing a concrete driveway. He was sketchy with some of my questions, so I doubt I'll be using him regardless. But in particular, I asked him how far down he would excavate down to install the driveway. He said he would excavate down to 4 inches (wtf!) then compact and level. I asked him why so shallow, and he said because it was gravel already and packed down by years of parking cars on it (15-20 years), to excavate, replace the gravel and pack it down again was pointless. I asked him "how do you know it's gravel all the way through" (I suspect it's just gravel poured on top, then clay soil underneath), he said he would judge it when they start excavating, if it's not, they would dig up to 4" deeper.

So he was planning on excavating to 4" deep, compact, level, rebar, than pour 4" of concrete. I believe it will be done in 3 sections, to match the original driveway. The area is a 10' x 22' gravel pad. There is a large deciduous tree in the neighbor's yard located approx 10' away (branches extend all the way to the far end of the gravel pad), so I was a little concerned there might eventually be roots heaving under the driveway. There are also neighbor's bushes lining the driveway.

My question is how would you install a concrete driveway in this situation? Is there some merit to his excuse for such a shallow depth?
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Old 07-27-2013, 01:30 PM
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SVA_Concrete SVA_Concrete is offline
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Quote:
Originally Posted by Janina5309 View Post
So I had a contractor give me a quote on installing a concrete driveway. He was sketchy with some of my questions, so I doubt I'll be using him regardless. But in particular, I asked him how far down he would excavate down to install the driveway. He said he would excavate down to 4 inches (wtf!) then compact and level. I asked him why so shallow, and he said because it was gravel already and packed down by years of parking cars on it (15-20 years), to excavate, replace the gravel and pack it down again was pointless. I asked him "how do you know it's gravel all the way through" (I suspect it's just gravel poured on top, then clay soil underneath), he said he would judge it when they start excavating, if it's not, they would dig up to 4" deeper.

So he was planning on excavating to 4" deep, compact, level, rebar, than pour 4" of concrete. I believe it will be done in 3 sections, to match the original driveway. The area is a 10' x 22' gravel pad. There is a large deciduous tree in the neighbor's yard located approx 10' away (branches extend all the way to the far end of the gravel pad), so I was a little concerned there might eventually be roots heaving under the driveway. There are also neighbor's bushes lining the driveway.

My question is how would you install a concrete driveway in this situation? Is there some merit to his excuse for such a shallow depth?
His methodology sounds very typical for a driveway. Driveways are usually installed 4" thick over top of compacted soil. THe rebar is a good thing to add strength.

If you want gravel base included as part of your price ask I am sure that he will do it for a cost of course.

You will never win a battle with he tree, unless you cut it down and dig all the root material out.
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Old 07-27-2013, 02:03 PM
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alldayrj alldayrj is offline
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Sounds good to me, i would use wire mesh instead of rebar. Poured in two sections
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Old 07-27-2013, 02:26 PM
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zedosix zedosix is offline
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I think if you were in Canada, that would not suffice, if you are in Florida then it would be good. You mentioned clay so I'm thinking its not that far south. If you were to call me for this project I would give two prices, one based on full excavation and possible tree-root removal. Second one being just as he quoted you.
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Old 07-27-2013, 02:42 PM
Red Shed Landscaping Red Shed Landscaping is offline
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If it were my driveway I wouldn't do less than 6 inches since we live in a frost prone area. Most of the concrete contractors around here will put down 3-4" of 3/4" clean gravel under the slab instead of sand like they used to use.
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Old 07-27-2013, 03:08 PM
Janina5309 Janina5309 is offline
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I live in calgary, alberta, canada.

I do live with frost, and with our chinooks, there are probably more freeze/thaw cycles than normal. A couple of you mentioned problems with being in Canada and in frost zones. Is this because of the moisture that sits in the clay soil that is expanding and contracting with freeze/thaw?
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Old 07-27-2013, 04:06 PM
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zedosix zedosix is offline
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Originally Posted by Janina5309 View Post
I live in calgary, alberta, canada.

I do live with frost, and with our chinooks, there are probably more freeze/thaw cycles than normal. A couple of you mentioned problems with being in Canada and in frost zones. Is this because of the moisture that sits in the clay soil that is expanding and contracting with freeze/thaw?
You definitely want to dig more than 4 inches for your concrete. You are basically in the same zone as where we are, and you must have at least 10 inches of good granular stone preferably clear, with wiremesh and I would use minimum 4000 PSI with air. Best thing you can do is call the concrete supplier he will tell you automatically what needs to be done in your area that will be your best advice
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Old 07-27-2013, 05:42 PM
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alexschultz1 alexschultz1 is offline
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Did he mention anything about checking with the city? A new driveway in my area has to be approved b/c of things like buried cables/sewer, right of way, and water run-off. 4000 psi for severe weathering, 6" base and 4" poured. (150mm base, 100mm poured concrete)
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Old 07-27-2013, 06:05 PM
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SVA_Concrete SVA_Concrete is offline
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I should have prefaced my post with a climate disclaimer. I am in beautiful south east Virginia and assume everyone on here is


A deep frost line does require clean stone for frost protection.
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