2B Stone in Pennsylvania: Clean 3/4 Inch for Drainage and Base Work

In the Poconos the working season is short at both ends. Snow lies late, the ground stays soft well into spring while the frost comes out, and by the time it has dried enough to build on, the calendar has already eaten a couple of months. Frost here runs 36 to 42 inches, so whatever goes in has to get in during the dry stretch and has to keep draining once it is buried. 2B stone is the size most mountain jobs around here are built on: clean angular crushed stone at roughly three quarters of an inch, with the fines screened out so water keeps moving through it.

The failure this stone is bought to prevent on mountain ground

The thing that wrecks a base up here is not the cold. It is water sitting in a layer when the cold arrives. Saturated material under a drive, a pad or a wall lifts as it freezes, drops as it thaws, and does it again a dozen times over a winter. By spring the pad has a hollow in it, the wall has leaned a fraction, or the drive has a soft patch that was not there in October.

Clean stone breaks that cycle by not holding the water in the first place. The voids between the pieces stay open, and anything that gets in has somewhere to go, provided you have given it an outlet.

2B stone, #57, drain rock and modified stone told apart

Four listings on this site look alike to a buyer and are not interchangeable.

2B is the Pennsylvania yard name for the clean three quarter inch size. #57 Stone is the AASHTO number for that same size, so a contractor's list saying #57 and a neighbor saying 2B are asking for the same thing. Which name you use depends on who you are talking to.

Drain Rock is the step up and out: a washed 3/4 inch to 1-1/2 inch grading sold for buried drainage, so it takes in a coarser range than 2B does. Where the run is a French drain, a leach field or a footing drain, that is the listing. Bigger again is #4 Crushed Stone, the open size for construction entrances and for subgrade over genuinely bad ground.

2A Modified is the opposite material. Dense graded with the fines left in, it compacts into a firm crust, and it is what a driveway surface is built on. Put it in a drain and the fines close the run within a season.

What clean stone does on stony till that stays wet until May

Mountain and glaciated ground holds a dense layer under the till, and water perches on top of it. That is why a trench dug in April fills up and a hole dug in August does not.

Two things follow. A clean stone layer here is doing drainage work whether you meant it to or not, so it needs a low point and a route out; stone in a bathtub with no outlet is a reservoir. And fines will migrate into it from the surrounding soil, which is what silting looks like a few years later, so wrap it in filter fabric.

Getting it laid and compacted before the ground softens again

Work it in lifts. Spread 4 to 6 inches at a time, compact each lift, and do not try to place the whole depth and hit it once. The angular faces lock against each other under a plate compactor, and a layer built this way carries weight while staying open.

Against a wall, place and consolidate in lifts as the wall goes up rather than dumping the backfill in one go, and keep it separated from the soil behind it with fabric. In a trench, the stone surrounds the pipe rather than sitting on it, so bed it, haunch it by hand, then cover.

None of this works on frozen or muddy ground, which is what makes the mountain window matter.

Patio base, creek line and fire ring, sorted by which is a drainage job

Three follow-on jobs come up and they split on that single question.

A paver patio base can be this stone, and in the mountains it often should be. A standard build uses a compacted dense-graded base of 2A modified with a screeded bedding course. An open-graded build uses clean stone all the way through, with #89 Crushed Stone as the bedding and joint fill, and it drains rather than shedding. On ground that stays wet, the open-graded build is the safer one.

A dry creek bed is decorative first. Clean angular stone works as the drainage layer under it, but the visible channel wants River Rock, because angular stone reads as construction rather than as a streambed.

A fire pit surround works with 2B as it is. The stone will not burn, it drains after rain, and at three quarters of an inch it stays put underfoot.

Tons for a 16 by 20 patio base and 52 feet of pipe trench

Hypothetical examples, worked as square feet times depth in feet, divided by 27. This site's calculator pages put the 3/4 inch clean family at about 2,800 lb per cubic yard, which is near enough 1.40 tons per yard.

For an area that is not a rectangle, cut it into rectangles, triangles and part circles, work each one and add the results. A triangle is half the base times the height; a circle is 3.14 times the radius squared, which is where the 63.6 and 19.6 square feet in the last line come from. The stone calculator will convert your own yardage if you would rather check the sum.

Keeping a clean stone layer honest through a plow season

Clean stone does not wear out, but it does move and it does silt. On a surface layer, a plow blade pulls stone into the shoulder and tires push it to the outside of a bend, so rake it back in spring and expect a light top-up every few years. Buried, the thing to protect is the fabric, because anywhere the stone meets bare soil is where silt starts working in.

Check the outlet of any drainage run after a heavy thaw. If water is standing in the stone rather than leaving it, the problem is at the end of the run, not in the material.

When you have the tonnage, set a quantity and a delivery date on this page. Delivery is arranged at checkout by ZIP code, and the truck needs firm standing to tip on with room to pull forward. Mountain lanes soften fast after rain, so pick the drop spot with that in mind and raise anything tight through Contact before the date.