Thermal barrier

Product Description

MONOKOTE® Z-3306 thermal barrier is a cementitious fire protective coating specifically formulated for application over rigid, urethane and polystyrene foam plastics. Spray applied to interior foam surfaces on walls and ceilings, the product forms a hard, durable, monolithic thermal barrier against heat and fire.

Monokote Z-3306 thermal barrier is a mill-mixed product requiring only the addition of water. It can be easily applied to required thickness in a single pass resulting in an efficient, low cost method of meeting building code and insurance requirements

In developing Monokote Z-3306 thermal barrier, GCP Construction Products 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 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 foam plastics for most building occupancies is permitted only when they are protected by an approved thermal barrier. 

Monokote Z-3306 thermal barrier has been successfully fire-tested and listed by Underwriters Laboratories Inc. Intertek and Factory Mutual. This product has a proven field and laboratory record of performance, reliability, ease of application and low in-place cost.

  • Proven fire test performance - Monokote Z-3306 thermal barrier has successfully passed all International Building Code (IBC) and National Building Code of Canada (NBC) requirements as a thermal barrier over foam plastics.
  • Economical - Ease of installation makes this product a low cost way to protect foam plastics.
  • Workable - After being spray applied, Monokote Z-3306 thermal barrier may be lightly trowelled.
  • Damage resistant - Monokote Z-3306 thermal barrier dries to ahard, durable surface which resists damage.
  • Humidity resistant - Monokote Z-3306 thermal barrier can be used in high humidity conditions and reduces sweating often experienced in vegetable storage areas.
  • Washable - When trowelled and painted, it can be washed and cleaned.

Physical Properties

  • Bond strength - 500 lbs/ft2
  • Color - Gray or off-white
  • Theoretical yield - 25 bd ft/bag (50 ft2 at 1/2 in. thickness)


Monokote Z-3306 thermal barrier is packaged in poly-lined bags for easy handling and storage.

Firebond Concentrate (bonding agent) must be applied to all surfaces before application of Monokote Z-3306 thermal barrier.

Monokote Z-3306 thermal barrier is mixed with water in a plastertype mixer to form a consistent, pumpable slurry. This slurry is then spray applied.

Where desired, the natural sprayed texture of the product can be lightly trowelled to form a semi-smooth, paintable surface. A thin (nominal 1/16 in.) latex stucco overspray may be applied to form a hard eggshell finish, capable of withstanding significant physical contact and surface abratsion.

Typical Applications*

Monokote Z-3306 thermal barrier may be used to protect foam plastics in many types of buildings. The following is a brief list of typical applications:

  • Breweries, freezers and coolers
  • Controlled atmosphere apple, potato and vegetable storage
  • Ice arenas and recreation centers 
  • Indoor tennis courts and swimming pools
  • Pig and dairy barns
  • Seed storage and processing
  • Water treatment plants

*NOTE: Many food processing applications require local inspection agency approvals in advance of installation

Test Agency Test Method Substrate Thickness of Z-3306 Test Results
Underwriters Laboratories Inc. (ULI) (USA) UL 1715 (Room fire test) Urethane foam 3/8 in. (10 mm) Passed
  (UBC 26-3) Styrene foam 3/8 in. (10 mm) Passed
ULI (USA) ASTM E119 Exposure (UBC 26-2) Urethane foam 3/4 in. (19 mm) 15 minute rating
    Urethane foam 1 1/8 in. (29 mm) 30 minute rating
ULI (USA) ASTM E84 Exposure (Tunnel test) Urethane foam 1/2 in. (13 mm) Flame spread 10 Smoke developed 5
    Styrene foam 1/2 in. (13 mm) Flame spread 5 Smoke developed 0
Intertek CAN / ULC S101-14 Urethane foam 1 in. (24 mm) 10 minutes
      1 in. (24 mm) 20 minutes
      1 in. (24 mm) 40 minutes
ULC (Canada) CAN4-S124M Urethane foam 7/8 in. (21 mm) Classification A
    Urethane foam 11/16 in. (16 mm) Classification B
    Urethane foam 13/16 in. (20 mm) Classification C
    Urethane foam 11/16 in. (16 mm) Classification D
    Urethane foam (23 mm) Passed
Factory Mutual Systems FM 4975 Urethane foam 7/8 in. (21 mm) Delay ignition 10-15 minutes
    Styrene foam 1 1/8 in. (29 mm) Delay ignition 10-15 minutes | 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 is a trademark, 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.

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