Ballast Rock Delivery

What ballast rock is for

Ballast rock is simply large washed stone — big enough and heavy enough that wind, water or traffic will not move it. Where #57 would scatter or wash out, ballast stays put.

The size band people mean by "ballast" runs roughly three-quarters of an inch up to two and a half, which covers the AASHTO No. 4 and No. 3 gradations. Which one you want depends entirely on the job, and the three main jobs are quite different from one another.

Roof ballast — the big one in South Florida

A great many flat commercial roofs here are single-ply membrane held down by stone rather than fully adhered. The stone is the fastening system, and in a hurricane zone that is a structural decision rather than a finish.

Ballast weight is typically specified somewhere around 10 to 13 pounds per square foot for the field of the roof, with heavier stone or pavers at the corners and perimeter where wind uplift is highest. The industry reference is ANSI/SPRI RP-4.

Do not choose roof ballast from a supplier page, including this one. The size, the weight per square foot and the corner treatment come from the roofing system manufacturer and the wind design for your specific building. Send us that specification and we will match it. We are very comfortable saying we are the wrong people to set it.

One practical note: roof ballast is usually washed river rock or washed crushed stone, and it must be clean. Fines on a membrane roof migrate to the drains and block them.

Construction entrances

A stabilised construction entrance is a pad of large stone at the point where vehicles leave a site onto a public road. Tyres drop their mud on the stone instead of on the street, and it is very often a permit condition rather than a nicety.

Ballast rock is the standard material because it is large enough that tyres cannot pick it up and angular enough to knock mud loose. A typical entrance is 6 to 12 inches thick over filter fabric, 50 feet long and as wide as the access.

The fabric matters. Without it the stone works down into the mud within a fortnight and you buy it twice.

Ordering

Ballast is sold by the ton at roughly 1.35 tons per cubic yard, and our minimum is one cubic yard like everything else.

For roof work, tell us the roof area and the specified pounds per square foot and we will convert it. For a construction entrance, give us the dimensions and thickness. For anything with a stamped specification, send the sheet.

Roof deliveries need planning. Stone has to get from the truck to the roof, which usually means a crane, a conveyor or a hoist that somebody has to arrange. Tell us what is happening at your end so we time the delivery to it rather than leaving twenty tons on the car park.

Specification

Figures are typical, not guaranteed. Weights and gradations vary between pits and sources. If your job is specified, send us the relevant plan sheet and we will match it — and confirm quantities against your own scale tickets once you are running.

What it is used for

• Ballast on flat single-ply membrane roofs
• Stabilised construction entrances, to stop tracking mud onto public roads
• Railroad and spur track ballast
• Heavy erosion control and high-flow drainage
• Temporary haul roads and equipment laydown over soft ground
• Large-scale French drains and dry wells where #57 is too fine

Working out how much you need

Material is sold by the ton. Plans are drawn in cubic yards. That mismatch is where most ordering errors come from, and they are expensive in both directions — running short stops a crew, and over-ordering by a large margin ties up money in a pile.

The arithmetic: multiply length by width by depth in feet, divide by 27 to get cubic yards, then multiply by the material's weight per yard. Most rock runs about 1.35 to 1.4 tons per cubic yard; compacted base is heavier at roughly 1.65; topsoil is lighter at about 1.15.

Then allow for compaction. Base and fill lose roughly 20 to 25 percent of their loose volume once they are properly compacted, so the tonnage you order should be above the theoretical plan volume. Our tonnage calculator builds that allowance in and converts the answer into truckloads.

Order slightly heavy. Two extra tons in a pile costs almost nothing and always gets used. Two tons short on a Friday afternoon costs you a whole extra delivery and a crew standing around.

Ballast Rock — common questions

Where we deliver Ballast Rock

From Jupiter down to Key West — Broward, Miami-Dade, Palm Beach and Monroe counties. Mainland deliveries are same or next day; the Keys are scheduled runs.

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