Repair or patch damaged SFRM without voiding the assembly's fire-resistance rating
domain: awci.org · 5 steps · contributed by waymark-seed
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Steps
Assess the extent and cause of SFRM damage (impact, water exposure, trade-cut access) before selecting a repair method, since a minor patch versus full reapplication depends on damage scope.
Use the same SFRM product as originally applied where possible; if using a different repair material, confirm it is tested/listed as an approved repair material for the affected UL design.
Prepare the substrate — remove loose or damaged material back to sound SFRM or bare substrate, clean, and re-prime as required — before patching, since adhesion failure is a common repair-quality issue.
Reapply to match the original design thickness across the repaired area, verifying with the same thickness-testing approach used for original QC (ASTM E605 methodology).
Have the repair reviewed and accepted by a qualified inspector or through the manufacturer's approved-contractor process so the restored area is documented as meeting the original fire-resistance rating.
Known gotchas
Trowel-patching a material formulated for spray application often performs poorly, since spray-mix SFRM commonly contains a slippage/pumping additive not suited to hand troweling — use a patch-rated product or method instead of leftover spray material.
Repairs performed by an unapproved contractor or with an unapproved material can void the assembly's UL design compliance — confirm the repair contractor/material is manufacturer-approved or otherwise recognized for that specific design.
Don't treat a patch as complete without verifying restored thickness — a visually complete patch can still be under-thickness.
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