Safety Surfacing Calculator

Because those two materials are unitary surfaces installed at a fixed thickness -- poured rubber or interlocking tiles don't settle the way loose-fill material does, so there's no compaction to allow for. This calculator sources Install Depth With Compaction (in) for Poured-in-Place Rubber and Rubber Tiles from a separate, manufacturer-typical unitary depth reference (not Minimum Depth (in), which is a loose-fill-only figure) no matter what Compaction Allowance (%) is set to; the field only affects Install Depth With Compaction (in) -- and everything computed from it -- for the three loose-fill material types (Engineered Wood Fiber, Rubber Mulch, Pea Gravel).

Minimum Depth (in) uses a three-tier version of the CPSC loose-fill depth table: 6 in for a critical fall height of 5 ft or less, 9 in for anything from just above 5 ft up through 7 ft, and 12 in above that -- but it's a LOOSE-FILL-ONLY figure. Poured-in-Place Rubber and Rubber Tiles never use it for Install Depth With Compaction (in), volume, weight, or cost; they're sourced from a separate unitary reference instead (see the next question), typically much thinner (roughly 2-5.5 in across this calculator's declared range) than the loose-fill table's 6-12 in. Minimum Depth (in) is still shown for unitary materials, but purely as loose-fill context, not as their actual install depth.

Two reasons, not one. First, the pricing MODEL differs: the three loose-fill materials (Engineered Wood Fiber, Rubber Mulch, Pea Gravel) are priced by the cubic foot -- you're buying bulk volume, so Estimated Material Cost ($) scales with surfacing area times install depth -- while Poured-in-Place Rubber and Rubber Tiles are unitary surfaces priced by the square foot of coverage, with an added per-inch surcharge above a 2.5 in base thickness. Second, the DEPTH feeding that surcharge differs too: unitary materials use a manufacturer-typical depth reference sized specifically for thin, engineered surfacing systems (roughly 2-5.5 in across this calculator's range), not the much deeper loose-fill table -- CPSC doesn't publish a unitary depth table at all, directing installers to the specific product's own ASTM F1292 test certificate instead.

No. Minimum Depth (in) and Install Depth With Compaction (in) are both driven entirely by Critical Fall Height (ft) and, for loose-fill materials, Compaction Allowance (%) (for unitary materials, by Critical Fall Height (ft) alone) -- Surfacing Area (sq ft) only scales how much material and money that depth requires across your footprint (Volume Needed, Weight, Estimated Material Cost, and Dump Truck Loads all grow with area, but the depth figures themselves don't move at all).