Perlite and vermiculite plasters consist of a blend of expanded perlite or vermiculite aggregates with either neat gypsum or portland cement. When properly mixed with water they can be applied to walls and/or ceiling surfaces, or to metal wire-lath or gypsum lath for fireproofing structural steel. Both gypsum and cement plasters also can be used for lightweight insulating curtain wall construction and stairwell encasement. Savings in weight, space, labor and building materials are possible.

Gypsum Plaster: Perlite plaster aggregate mixed with gypsum provides an ideal base coat plaster for interior walls and ceilings and for membrane fireproofing to the underside of floor and roof assemblies, or structural steel members.

Sprayed-On Fire-Protection with Schundler Cementitious Fireproofing The Schundler Company has been manufacturing cementitious sprayed-on fire proofing materials for over ten years. In the fall of 2003, it introduced some of its own brands. Currently, it no longer manufactures spray-on fireproofing materials. Nevertheless, for reference purposes, the following links are provided: Schundler Classic 5 LD Schundler Classic 5 LD Application Guide Schundler Classic 5 MD Schundler Classic 5 XY

Portland Cement: Perlite-portland cement based plaster can be used on new new or on renovation work - as a base coat for stucco finishes, ceramic tile, or masonry veneer. Perlite portland cement plasters are approved for as much as 4-hour fire protection of structural steel columns. They are ideal for weather exposed structural steel elements re-quiring fire protection. Sand aggregate can be added to increase compressive strength. Where desirable all plasters containing portland cement must be applied over metal, or wire lath or other suitable surfaces prepared with an approved liquid bonding agent. Plastering on metal or wire lath is typically three-coat work but some building codes allow two-coat plastering under certain conditions. Two-coat plastering is most typically used in repair and remodeling operations.

Advantages:

• Lightweight - Weighs approximately 60% less than ordinary sand plaster, saving about one ton (907 kg) for every 100 yd² (83.6 m²) of material applied ½ in. (13 mm) thick.
• Insulating - 4 times more resistant to heat transmission than sand plaster... permits savings in heating and air conditioning costs... conserves energy.
• Fire Retardant - Non-combustible and non-toxic ... provides up to 5-hour fire protection with minimum weight and thickness ... more than 50 fire tested designs by recognized laboratories.
• Noise Reduction - Reduces sound transmission between partitions. (also see ¹ below)
• Adaptable - Packaged in 3 or 4 cubic feet (85 or 113 liter) bags in the United States and Canada and in 100 liter bags in most other countries. Easy to measure, mix and handle... job mixing permits proper proportioning to meet different plaster based materials specifications.
• Durable--Cannot rot or decay...strong but not brittle... endures freeze-thaw exposure... successfully used on major construction projects since 1946.

• Perlite and vermiculite plasters provide protection for columns, partitions, and the undersides of floors and roof assemblies. This protection can be applied with either rough finishes, or in attractive, durable finish.
  

  During a fire, adequate fire protection demands that the temperature of the load bearing members be maintained below the critical point at which weakening or failure is likely to occur. Repeated test over many years have demonstrated that both perlite-gypsum plaster and vermiculite-gypsum plaster are exceptionally effective in blocking flames and retarding the transmission of heat. When exposed to flames, perlite and vermiculite plasters release chemically combined water in the form of water vapor which helps maintain the plaster temperature to below 212 ⁰F until all of the water has been driven off as steam. Meanwhile, the insulating action of the perlite or vermiculite aggregates delays the release of steam and retards the transmission of heat, thus improving overall fire-proofing characteristics.

  Unlike ordinary sand plaster which can expand and "explode" during fires and/or when subjected to high temperatures, perlite and vermiculite plasters have low linear expansion characteristics which greatly reduce the number and size of cracks. By reducing the number and size of cracks through the plaster, the heat and flames of a fire cannot penetrate the plaster surface as easily or quickly.