Application methods, equipment, and installation procedures
The equipment train
Typical SFRM equipment is a paddle mixer, a positive-displacement or piston pump, a hose, and a spray nozzle with an air supply and water source. The inspector confirms the pump and nozzle are suited to the product, the hose length and diameter are within the manufacturer's limits, and gauges are working. Mixing follows the bag or silo instructions: measured water, specified mix time, and no retempering after the pot life expires.
Application rules
Apply perpendicular to the surface at the manufacturer's distance, using overlapping passes. Most products limit each pass (often ¼–½ in.) and require the previous pass to set before the next. Build to the listed thickness rather than 'eyeballing' a single heavy coat. Protect adjacent work and coordinate with other trades so ducts, hangers, and equipment are not installed through wet or uncured material.
Worked example
The specification requires 1½ in. on a beam; the data sheet says maximum ½ in. per pass and 1 hour between passes. The crew applies ¾ in. in one pass and plans a second pass. Correct call: reject the first pass as too thick, remove it or allow it to set only if the manufacturer permits, then apply three ½ in. passes and verify each cured thickness with E605 before close-out.
Traps
Adding water to stretch a batch; spraying from too far away, which creates dry, low-density material; applying over dust or frost; letting other trades damage uncured SFRM without repair.