Perimeter Fire Barrier Calculator

A perimeter fire barrier closes the gap between the edge of a floor slab and the inside face of a curtain wall — the joint every floor in a high-rise glass building needs, so fire and smoke can't travel vertically through that seam from floor to floor. Total Safing (sq ft) is simple area math done twice: perimeter length times gap width (converted to feet) gives the safing area for one floor, then that figure is multiplied by Number of Floors, since the same detail repeats identically up the building. Mineral wool batts, sealant cartridges, and impaling clips are all downstream of that one area figure — batts from safing area divided by a standard 8-square-foot batt, sealant cartridges from a fixed 1 fl oz per linear foot of top-and-bottom bead, and clips from one per foot of perimeter per floor.

Two inputs on this page look like they should matter and don't: Fire rating (hrs) and Safing thickness (in) both sit on the form and print in the step-by-step breakdown, yet neither one is referenced anywhere in the actual cost or quantity formulas. Doubling the fire rating from 2 to 4 hours, or the safing thickness from 4 to 8 inches, leaves every batt count, cartridge count, clip count, and dollar figure on this page byte-for-byte unchanged — the real UL system selection (and its actual mineral wool density and thickness) has to come from your assembly drawings, not this calculator's output. Treat both fields as documentation, not as levers.