Gravel parking pad--thickness?

Brad54 · Oct 21, 2010

This is probably closest to the proper forum, since it's next to my shop and will hold cars and trailers...

I'm going to gravel a 40-foot long, 25-foot wide pad next to my shop in the coming months.
Once the gravel is in, I'll compact it with a vibrating "Whacker Packer" to make it pretty solid. This should be a ton cheaper than concrete.

The question is, how deep does it need to be? 4 inches seems the minimum, but I'm wondering if 6 inches would be overkill.

I'll park an open car trailer (sometimes loaded), a boat and cars on it.

thoughts?

-Brad

D.J. · Oct 21, 2010

Make sure you install fabric under your gravel so weeds and grass will have problems in growing on and into your pad and 4" seems plenty thick to me especially if compacted.
________
Wellbutrin withdraw

Brad54 · Oct 21, 2010

My neighbor rocked his flower beds around the house, and spent a ton of time putting plastic down under it, thinking the weeds wouldn't grow through the plastic.
The damn things just grew up through the gravel!

I will Round-Up the pad frequently.

I am, however, thinking about something for drainage, since the pad is at a slight angle front-to-back.

-Brad

NZMacca · Oct 21, 2010

Just did our new farm truck parking pad the same way as you are considering. We have good free draining soil and just scraped the topsoil off and made a level 150mm thick GAP40 gravel pad. Then compacted the entire area. We found that spraying the gravel with water really helped it pack down and now its rock hard with not a weed in sight.

Kevin54 · Oct 21, 2010

Make sure you ask for extra stone dust. You can get 8's which is about 3/4" in size and a little smaller but they can add some extra stone dust in which will help with compaction. I would also go more than 4" deep for the stone. At least 6" minimum. Put a layer of stone down, dampen it. compact it. Add some more, dampen, then compact. It should be like concrete by the time you are done.

Fastback · Oct 21, 2010

Just go the local concrete plant and ask for washout, use it for a base...or the whole deal. You may be able to get it for free and it is a crushed concrete that packs down hard. You may decide to skip the stone all together.

scottzilla · Oct 21, 2010

+1. Use what we call in the NE RCA. Tamp it down, then put the gravel down. You will end up using MUCH less gravel this way (Gravel costs more than RCA) and have a solid base.
Weeds don't have to grow from the bottom. Wind and rain can install weeds from the top, right in the stone. Nothing a little RoundUp can't handle.

A1an · Oct 21, 2010

My grandparents had a huge gravel driveway at their house for around 40 or so years before they moved to a retirement home. No plastic liner and never had a big issue with weeds. If I remember correctly it was about 3-4 inches deep. I can only remember helping them add more gravel once in my life...not sure how often this had to be done.

NUTTSGT · Oct 21, 2010

Not sure where you are at but I would get it down before the snow flies. It'll settle some moreover winter with the fost heaving. Just add another load of stone in the Spring.

D KRAGER · Oct 21, 2010

4" deep should be fine.

Use the fabric, not really for weeds, but this keeps the rock separate from the soil underneath. When the ground in frozen deep down in the early spring and the top thaws out, this keeps the mud from coming up through the rock and making it a muddy soft mess.

If you don't want to use fabric... Put down a layer of bigger rock (2-3"). Then top that with smaller rock to fill in the voids. The large rock underneath gives a good base so that you don't get ruts when the ground is soft.

larry_g · Oct 21, 2010

D KRAGER said:
4" deep should be fine.

Use the fabric, not really for weeds, but this keeps the rock separate from the soil underneath. When the ground in frozen deep down in the early spring and the top thaws out, this keeps the mud from coming up through the rock and making it a muddy soft mess.

If you don't want to use fabric... Put down a layer of bigger rock (2-3"). Then top that with smaller rock to fill in the voids. The large rock underneath gives a good base so that you don't get ruts when the ground is soft.

This is the way I would do it. Some of what you do depends on your soil type. Are you on the top of the hill with good drainage, or the bottom where the water collects? If your on loose or muddy soil then the first layer of larger rock is more important. Now I speak from a background of where we are not subject to deep freeze and thaw in the ground. If your in a heavy freeze zone then adjustments may have to be made.

lg
no neat sig line

Fastback · Oct 21, 2010

4" wont cut the nut, sorry. If I am doing a driveway I cut out the top soil at least 6" if not more...but then again the back fill can be free if you shop around, the top coat could cost as much as $20 a ton, but that only needs to be a few inches deep, if you go too thick motorcycles fall over when the rider hits the quicksand, too thick and it feels like pea gravel.

I dont use fabric, even in mulch beds.

Just my .02

drmoonshine · Oct 21, 2010

4 or 5 inches. Your definitely going to want more that if you were using concrete but it will still be cheaper.

Brad54 · Oct 21, 2010

I'm in Georgia. The ground is hard packed red clay. It's like concrete when you dig in it--actually, you don't dig, you pick-axe it, but it gets real greasy when it's wet.
The tip for putting down fabric to keep the mud separate from the rock is a great idea, as I can definitely see the rocks sinking down into the top inch of the clay when it gets good and wet. I hadn't thought of that before.

I've also had a few guys suggest "Crush And Run" on top of it. I'm not real familiar with the product, but from what they've said, if I put it on top of the gravel, tamp it in, and then run a garden sprinkler over it for a couple hours, it'll harden almost like concrete.

Thoughts?

-Brad

Herb · Oct 21, 2010

When I redid my driveway I used what is called 6" minus layed down 12-16'' thick and compacted by both the tri axles and a 42,000 lb vibratory roller. My driveway is 1300 ft + a 65x 100 parking area. It's been 7 years and it's holding up fine. I would never go less than 6", always closer to 12''.

WVBrady · Oct 21, 2010

Brad54 said:
...I've also had a few guys suggest "Crush And Run" on top of it. I'm not real familiar with the product, but from what they've said, if I put it on top of the gravel, tamp it in, and then run a garden sprinkler over it for a couple hours, it'll harden almost like concrete.

Thoughts?

-Brad

It's actually "crusher run":

http://www.gernatt.com/Tools/Portfo...size=0&lngDisplay=1&jPageNumber=4&strMetaTag=

It does pack down very hard, but if the land is not level, it might wash out.

Dragster Racer · Oct 21, 2010

I have been doing the larger rock first, then after it is flattened out, bring in the fines, and pack it well. The large gives a good base, and tends to give better coverage per ton. Don't do it when it is muddy. You may as well throw money into a mud hole. Tried that!

Brad54 · Oct 21, 2010

Thanks guys.
Can't use the crusher run, because the land is sloped front-to-back.
The idea of a layer of larger rock on the bottom and smaller on top is a great idea--especially from a coverage-per-ton standpoint.

What sizes are you guys thinking of? I know I'll get good info from the quarry, but just for conversation sake here...
I bought several yards of gravel for a similar project about 9 or 10 years ago, but the rock size/label is fuzzy at this point.

-Brad

Oh, and Herb--that avatar is spectacular.

Dragster Racer · Oct 22, 2010

My dump truck guy just knows what I want when I say large and small. Large is about 2" roughly here. Not a lot of fines

jhelrey · Oct 22, 2010

Get 3/4 Limestone with Fines....

I would put in 6-8 inches.

Fabric is a waste of money. Roundup is not! Like said, weeds will grow between rocks, dirt clumps that drop off your vehicles, etc.

Scotto · Oct 22, 2010

With your hard soil, you're not going to need much gravel. At my parent's house they put down 1/2" gravel probably 20 years ago only a couple inches thick. Within 10 years it just sunk down into the soil and disappeared for the most part. The liken 10 years ago we added maybe 3" of 1-1.5" gravel. It's worked great - locked together and it's not moving. I'd put down a lesser amount - you can always add more later.

Gravel parking pad--thickness?

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