Gravel Delivery FAQ: Ordering Around a Michigan Spring

Most of what follows is really about timing. The working season here runs from the thaw into late fall, it is shorter north of the bridge, and frozen ground stops compaction outright, so a job is planned in one season and built in another. The questions below start with the things that go wrong before the truck is booked, then work through ordering, access and the day itself.

The mistakes that cost the most before anything is ordered

Our bank washes out every spring. What holds material on a slope?

Size and shape do the holding. Rounded stone rolls, so pea stone and river rock drift downhill on anything steeper than a gentle grade. Angular material locks together and stays put much better. Where snowmelt or a culvert outlet is doing the damage, the answer is RipRap placed over fabric in a thick layer, not a decorative skin of small stone. The fabric is not sold here, so it comes from a local landscape supplier. On a planted slope, shredded mulch holds better than bark nuggets, and terracing or an edge at the bottom will do more than any material choice. Set the toe of the slope first; water that undercuts the bottom will take the rest with it whatever is on top.

How do I tell #57 from 21AA standing over the pile?

Look for dust. Clean, washed stone such as #57 Stone or Drain Rock has had the small material taken out, so it stays open and water travels through the voids. A dense-graded mix such as 21AA or 22A has stone dust and fines deliberately left in, and those fines wedge between the larger pieces when the layer is compacted. Open stone drains and does not compact; dense-graded stone compacts and does not drain. Almost every material mistake on this site comes from swapping the two.

Will a drive that only sees a car need less 21AA than one a grain wagon crosses?

Load and subgrade both move the number, and the subgrade usually moves it more. A base spreads weight across whatever is beneath it, so soaked lake-plain clay in the southeast needs a thicker layer than sandy outwash on the west side for exactly the same vehicle. A drive that sees a car twice a day is a different case from one that carries a loaded gravel truck or a grain wagon in fall. There is no published depth here to hand you, so the honest version is this: take the guidance on the product page as a starting point, then add depth for wet ground, heavy vehicles and the soft stretches, and ask a local builder where the job is load bearing.

Names, and what to do with what is left over

Is leftover stone worth keeping over the winter?

Usually yes, if you can put it somewhere out of the way. Crushed stone and gravel do not spoil, and a small reserve is exactly what you want in April when the thaw finds two low spots in a drive. Keep it on a hard surface or on a sheet so it does not sink into the lawn, and cover it if you would rather not be picking leaves out of it. Soils and mulch are the exception: topsoil and garden soil compact and go sour under a tarp, and mulch breaks down, so those are better spread than stored.

I was told to get 21AA. Which product here is that?

21AA Limestone is listed under road base, and 22A Road Gravel is listed under crusher run. Those national labels are how the catalogue is structured; the local class designation is what the material is actually called around here. The same applies further down the list, where pea gravel is sold as pea stone. Match on size and grading rather than on the name, and remember that 21AA and 22A are different MDOT Section 902 classes, not two words for one product. The class is how material gets specified locally, not a certification this storefront carries.

Layers, and ground still coming out of the thaw

The drive wants a base and a top course. Which do I work out first?

Treat them as two orders that arrive together. Work out the base first, because it is the thicker layer and its depth is set by the ground, then the surface course on top of it. Calculate each in its own tool, since each uses a different weight per cubic yard, and add both to the same order. Build the base, compact it properly, and only then spread the surface. A surface course laid over loose base material inherits every soft spot underneath it.

The thaw has left the site soft. Does that hold up the delivery or the compaction?

Wait for the compaction, but not necessarily for the delivery. Material can sit in a pile; what will not work is rolling a layer over ground that is still giving underfoot. As frost comes out of the ground the trapped water leaves the soil with almost no strength, and a base compacted into that will move again when it dries. Frost laws limit heavy trucks on state highways and many county roads through the thaw anyway, and they lift later up north than downstate, so the calendar often makes the decision for you.

In what order do the subgrade, the 21AA and the surface course go down?

From the bottom: a shaped, compacted subgrade with a crown or a cross-fall so water leaves rather than stands; then the dense-graded base, which is 21AA Limestone for most drives or 22A Road Gravel on a lane, compacted in layers rather than in one lift; then the surface course, usually Driveway Gravel. Where water collects at an edge or across a low stretch, a trench of open washed stone alongside the drive does more good than extra base under it. Frost reaches 42 inches under the Michigan Residential Code, and a building official can require deeper footings, which is why base depth here is argued about in terms of winter rather than traffic.

Still stuck on a number? Work the quantity out with the material calculators, which also handle tons against yards and the weight behind a given volume, or send your measurements through the contact form. The delivery page has the checkout fields, the lane and the tip, plus what happens after an order is in: material you turn out to be short of goes on a fresh order rather than into one with a date against it, under the refund and order-change policy published there.

Who operates Michigan Rock Supply?