Joint Firestop System Calculator

Calculate joint firestop system requirements for construction joints and gaps in fire-rated assemblies per ASTM E1966/UL 2079 and IBC 715

Input Parameters

Results

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Required Seal Depth
in
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Sealant Volume
fl oz
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Backer Rod Diameter
in
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Movement Capability
%
Note: Joint firestop systems must be tested to ASTM E1966 and listed by UL (UL 2079). Movement capability must exceed expected building movements including thermal expansion, seismic drift, and structural deflection. Always reference specific system numbers.

Reference

ASTM E1966 (UL 2079) / IBC Section 715 Joint systems tested per ASTM E1966 standard fire exposure Backer rod: 25-33% larger than joint width for compression Sealant depth: typically 1/2 to 2x joint width Movement capability: +/- 25% to +/- 50% typical Expansion joints require higher movement ratings Head-of-wall: must accommodate deflection