Thermal barrier

Product Description

MONOKOTE® Z-3306/G Thermal Barrier is a gypsum based fire protective coating specifically formulated for application over sprayed polyurethane foam plastics (SPF) with a nominal density of 0.5 pounds per cubic foot (pcf). Spray applied to interior foam surfaces on walls and ceilings, Z-3306/G forms a well adhered, monolithic thermal barrier against heat and fire.

Z-3306/G is a mill-mixed product requiring only the addition of water. Prior to application of Monokote Z-3306/G, the application of FIREBOND® Concentrate at a nominal rate of 500 ft2/gal is required to all foam surfaces. For maximum yield benefit and set characteristics, Z-3306/G can be applied using Monokote Accelerator.

With Monokote Accelerator, Z-3306/G can be applied to the required thickness in a continuous uninterrupted operation. This results in an efficient, low cost operation that meets building code and insurance requirements.

In developing Z-3306/G, GCP Applied Technologies has utilized its experience and technology as the producer of Monokote spray applied fireproofing products – the most widely used structural steel fireproofing brand in North America. Sales and technical service personnel located throughout the United States and Canada provide close technical support to contractors, owners and specifiers.


While specific requirements differ from locality to locality, the use of nominal 0.5 pcf SPF for most building occupancies is permitted only when they are protected by an approved thermal barrier. Z-3306/G has been successfully fire-tested for performance, reliability, ease of application and low in-place cost.  

  • Proven fire test performance - Z-3306/G has successfully passed the International Building Code requirements for code compliant use as a thermal barrier over nominal 0.5 pcf urethane foam plastics.
  • Economical - High application rate makes Z-3306/G the low cost way to protect foam plastics. The use of Monokote Accelerator adds more savings by maximizing yield and set charcteristics reducing labor and time to complete the project
  • Damage resistant - Z-3306/G dries to a hard, durable surface which resists damage.

Physical Properties

  • Bond Strength (ASTM E736) - minimum 200 psf
  • Compressive Strength (ASTM E761) - 1,200 psf
  • Density (ASTM E605) - minimum 15 pcf average; minimum 14 pcf individual
  • Color - Gray
  • Theoretical yield - maximum 44.5 bd ft/bag

In-place Performance

Test Method Thickness of Z-3306/G Test Results
(Surface Burning Characteristics)
N/A Flame Spread = 0
Smoke Developed = 0
NFPA 286/UL 1715 – Corner Room Test 3/4 in. (19mm) Passed


    Z-3306/G is packaged in kraft poly-lined bags for easy handling and storage.

    Firebond Concentrate (Bonding Agent) must be applied to all foamed surfaces at a rate of 500 ft2/gal prior to application of Z-3306/G. Firebond should be allowed to become tacky or dry prior to application of Z-3306/G.

    Z-3306/G is formulated for machine application in standard gypsum plaster type equipment. Z-3306/G is mixed with water in a paddle plaster-type mixer to form a consistent, pumpable slurry which is then spray applied to foamed plastic previously treated with Firebond Concentrate.

    Where desired, the natural sprayed texture of Z-3306/G can be lightly troweled to form a semi-smooth, paintable surface. After completely dry, Z-3306/G may be painted with acrylic and other paints formulated for interior use conditions over gypsum plaster based materials. Thin latex modified surface coatings may also be applied to Z-3306/G to increase surface hardness. All coatings must meet exposed interior use code requirements and surface burning characteristics (ASTM E84 of smoke < 450, Flame Spread < 200) Contact your GCP representative for guidance prior to application of coatings to Z-3306/G. So called “waterproofing coatings” of any kind will not prevent water penetration of Z-3306/G and may not be used.

    Typical Application and Limits of Use

    Z-3306/G may be used to protect foam plastics in many types of buildings. Monokote Z-3306/G is gypsum based and is designed for interior use only. Z-3306/G should not be used for exterior applications or exposure to continuous unconditioned high humidity environments or where free water may condense For high humidity or damp applications, GCP recommends the use of Monokote Z-3306 Portland Cement based Thermal Barrier. | For technical information:

    We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

    Monokote and Firebond are trademarks, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

    © Copyright 2017 GCP Applied Technologies Inc. All rights reserved.

    In Canada, 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6.

    GCP Applied Technologies Inc., 2325 Lakeview Parkway, Alpharetta, GA 30009, USA
    GCP (Hong Kong) Ltd., 6 On Chuen Street, On Lok Tsuen Ind Area, Fanling, Hong Kong
    This document is only current as of the last updated date stated below and is valid only for use in Hong Kong. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

    Last Updated: 2022-11-18