Too thick of gravel drive?

[Nic3456]

Is it possible to have to too thick of a gravel driveway? My contractor is mixing what he typically does with what the builder is recommending and I think it might be overkill. I will have a 550 foot long drive, 10 feet wide, Pretty flat, and no trees.

He's going to dig 12 inches deep (I think the topsoil is 9-11" deep) and then fill with 12" #2 stone and then 4" of #304. He recommends not spending more on the geofabric since we will have so much stone, but will put it in if I want. I feel like it's overkill, but his bid is in line with others.

We'll do top too dress later which would add another 2-4" down the road.

 

[coralhead]

That sounds about right on the depth. You need to get the topsoil(organics) out and I would use the fabric as well. Being that it is flat you may have some drainage problems that would allow water to collect that would soften the subsoil and the fabric will help from the rock being lost to soft subsoil. It is easier to put the fabric down and maybe not need it than it is to need it later.

 

[jk96]

I'm perplexed when I here about people basically digging a trench to fill with gravel for a road. Wouldn't it be better to crown the road leaving a ditch on either side to carry the water that sheds off the crown? 3" base rock on top of then cover with 1"? That's how we built our mile long drive 5 years ago and have had very little work to maintain.

 

[CalG]

the reasoning behind "the ditch" is to remove the organic top soil.

There is no advantage to build a road over mud.

 

[jk96]

the reasoning behind "the ditch" is to remove the organic top soil.

There is no advantage to build a road over mud.

The op must have some really soft soil compared to us. 16" of rock just seems crazy to me. We crowned the road without digging a trench for rock, put down about 5" of #3 and covered with another 2" of #1 and have had no issues for 5 years since. Just minor work each year after a major rain or two.

 

[CalG]

The op must have some really soft soil compared to us. 16" of rock just seems crazy to me. We crowned the road without digging a trench for rock, put down about 5" of #3 and covered with another 2" of #1 and have had no issues for 5 years since. Just minor work each year after a major rain or two.

Location, location. location

Your soil MUST be different than the OP. Heck, there is a gravel pit only a half mile from my place,
and all l have is ledge!

 

[4570Man]

Location, location. location Your soil MUST be different than the OP. Heck, there is a gravel pit only a half mile from my place, and all l have is ledge!

Same here except the gravel quarry is a little farther. 12" of topsoil must be nice. My yard is in desperate need of some topsoil. Grass won't even grow in places. The places that grass is growing on only have a couple inches of grass.

 

[LD1]

Our area is typically pretty solid clay once the topsoil is gone. If you do Ineed have 12", it all has to go. The question then becomes....how high above grade do you want the drive? If the area is nearly level....having the drive a few I i cheap above grade is a good thing. If you want a smooth transition from drive to yard....you can use alot of that topsoil that was dug out to feather out the edges.

I hope he is quoting limestone too. Gravel in this area sucks. Contains too much sandstone. And for those unfamiliar with our area....#2's are commonly used for base. This is 3"-4" diameter stuff. And 304's are a 1-1/2" minus stuff that has pretty high amount of fines, and locks the #2's together and packs real well.

12" +4" would handle full cement trucks in the wettest of years. It may sound like overkill....but will stand the test of time. For a light traffic drive, I'd go no less than 5-6" of #2's, about 3" of 304's, and top coat with a washed uniform sized stone. Typically #8's....which are 3/8"-1/2", or #57's which are about 3/4".

That results in a 8-10" thick drive. But like I said, if it's flat and you need 12" just to be rid of the topsoil....their proposal is exactally how I would do it but I would still add a too coat. The 8's and 57's are the most expensive. The #2's are the cheapest. Which is likely why he is quoting it so thick. To get the thickness you need I. The most cost effective way. You only need enough 304s to lock in the #2's and pack without the larger stuff coming to the surface. And it indeed packs like concrete. But results in a "dusty" drive with all the fines. That's why I like to topcoat on a residential drive.

 

[Nic3456]

Thanks LD, good to hear from someone familiar with my area. Would you also do the geofabric or would that be unnecessary?

 

[LD1]

Thanks LD, good to hear from someone familiar with my area. Would you also do the geofabric or would that be unnecessary?

I have never done geo-fabric, nor do I know anyone that has.

I would be extremely surprised if you had anything other than hard brown rocky clay under your topsoil. And IMO geo-fabric......especially going with a 12-16" thick drive.....is gonna be a waste of money.