Fire resistance enhancements for wall construction

Problem
Protection against fires is among the most crucial functions of building materials and requirements are increasing.

Desired properties
Low thickness of additional material and multi-functionality.

Category:
Deadline for concept summaries: August 31, 2018

Category 3: Fire resistance enhancements for wall construction
Improve occupant safety while reducing building cost and complexity

Problem statement

Protection against fires is among the most crucial functions of building materials. In light of recent catastrophic fires in Europe and the Middle East, pressure is mounting on architects and developers to improve building materials and design for better fire safety. This developing market trend poses challenges for traditional building materials suppliers.

Fire protection in frame wall assemblies is typically achieved by gypsum sheathing, either in a single layer, multiple layers, or combined with wood sheathing. The practice of utilizing multiple layers of sheathing in wall assemblies to achieve required levels of fire resistance is costly, and in fact it provides the bare minimum amount of protection in the event of a growing fire.

Building codes are now trending towards allowing combustible wood frame wall construction on taller buildings (i.e. podium-style construction), and there  are doubts about whether fire protection is keeping pace for these structures. New fire protection solutions are therefore needed to ensure safety.

Possible approaches

Any solutions that increase the fire resistance of building walls will be considered. Possible approaches could include additives to existing materials, configurations of components that increase fire resistance, and sprays, laminates, or roller-applied materials applied to sheathing products in the factory or on-site.

Known approaches not of interest

Unless significant performance/cost breakthroughs or innovative applications can be achieved, the following materials represent known state-of-the-art and are thus not of interest:

  • Solutions that fail to significantly outperform existing products (e.g. LP Flameblock)
  • Multi-layered gypsum sheathing
  • Combinations of wood and gypsum sheathing
  • Thick, heavy materials (e.g. traditional masonry and concrete)

Key success criteria

Required:

  • Additional thickness of the wall assembly is 1/8″ or less
  • Satisfies ASTM E119 standardized fire resistance test for hourly rating
  • Enhanced sheathing provides air barrier functionality

Desired:

  • Enhanced sheathing provides air and moisture barrier functionality
  • Water drainage capacity
  • Sound insulating capacity
  • Thermal barrier (i.e. R-value of 1 or more)
  • Easy handling, quick installation, and design flexibility
  • Environmentally sustainable manufacturing and disposal

Technical specifications [Cat. 3]: Fire resistance enhancements for wall construction

Property Standard Requirement
Surface burning ASTM E84 Flame Spread less than 25

Smoke Developed less than 75

Fire resistance ASTM E119 1 hour rating achieved over wood-based sheathing

2 hour rating achieved over 1 hour rated gypsum sheathing

Combustibility ASTM E136 or NFPA 220 Noncombustible
Air leakage resistance

(desired, not required)

ASTM E2178 Less than 0.02 L/s/m2 at 50 Pa
Water penetration resistance

(desired, not required)

AATCC 127 modified water column test Testing medium: 55 cm water column

Success criteria:

5 hours without water entry through joint or into sheathing

Water vapor transmission

(desired, not required)

ASTM E96 Greater than 10 perms for permeable membrane

Less than 0.1 perms for vapor impermeable membrane

Restrained environmental conditioning

(desired, not required)

ICC ES AC 212, Section 4.7 No cracking or water penetration after structural transverse loading and structural racking, followed by cycles of wetting, drying, and changes in temperature, and water penetration test.