How it works

A 1.5-inch cubical specimen is suspended in a furnace held at 750 degrees while thermocouples record temperature rise. To pass, the recorded temperature must not exceed the furnace baseline by more than 30 degrees, weight loss must not exceed 50 percent, and there must be no flaming after 30 seconds. Materials passing this test include concrete, steel, brick, ceramic tile, and gypsum board with a noncombustible facing.

Materials failing E136 are classified as combustible and require code-mandated clearance from heat sources. Wood framing, foam insulation, vinyl, and most plastics fail. The classification is foundational to NFPA 211 clearance requirements: combustible materials must maintain specified distance from chimneys and fireplaces, while noncombustible materials may be placed against them. Sweeps reference E136 status when evaluating mantel installations and hearth extensions.

DFW context

DFW homeowners installing custom mantels, hearth surrounds, and built-ins around fireplaces often use materials that look like stone or tile but are actually combustible substrates with thin facings. TSE technicians verify ASTM E136 documentation before approving such installations, particularly for floating mantels and reclaimed wood facings that would fail the test if checked. The June 2025 hailstorms also accelerated mantel and surround replacement, putting E136 questions in front of more homeowners.

Related terms

• [Combustible clearance](/glossary/combustible-clearance/)
• [Mantel clearance](/glossary/mantel-clearance/)
• [Hearth extension](/glossary/hearth-extension/)
• [Heat shield](/glossary/heat-shield/)

Sources

• ASTM E136 Standard Test Method
• NFPA 211 (2024), Section 12.7
• IRC 2021, Section R1001.11