Thermoguard Fire Varnish Overcoat (Exterior)
  • Thermoguard Fire Varnish Overcoat (Exterior)

Thermoguard Fire Varnish Overcoat (Exterior)


Thermoguard Fire Retardant Varnish Overcoat (Exterior) is for use in combination with and over Thermoguard Fire Varnish Basecoat in external applications.


  • For timber/timber derived substrates
  • Clear, UV and wear-resistant finish
  • Certificate of Supply available
  • Certificated when used over the basecoat:
  • BS EN Class B s2 d0
  • Class 1 and Class 0

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  • Current colour: Clear
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£64.80 Tax incl.


Intended Use – Clear Fire Protection Overcoat for Fire Varnish System for Exterior Wood

Thermoguard Fire Varnish Overcoat (Exterior)

Thermoguard Fire Varnish is a clear varnish system for the Fire Protection of timber and timber derived substrates to BS Class 1 and Class 0 Surface Spread of Flame as well as BS EN Class B s2 d0 (For 30 or 60 minutes Fire Resistance see Thermoguard Fire Varnish 30 & 60 Minute System). The system is made up of a basecoat and an overcoat that must be used together, the special formula provides a tough, durable finish to external wood (for interior surfaces see Thermoguard Fire Varnish Overcoat (Interior)). The clear finish enhances the natural beauty of the wood while providing protection against UV and wear as well as fire protecting new and previously varnished surfaces.

The Thermoguard Fire Varnish System is made up of Thermoguard Fire Varnish Basecoat which is a clear, intumescent varnish to be finished with Thermoguard Fire Varnish Overcoat (Interior) or Thermoguard Fire Varnish Overcoat (Exterior) available in a clear matt or satin finish (a gloss finish is available in both interior and exterior versions in batch quantities for large projects). The Thermoguard Fire Varnish Overcoats provide protection against UV, weathering (exterior grade) and wear whilst Thermoguard Fire Varnish Basecoat provides the Fire Protection.

Intumescent Fire Protection

When exposed to fire, the Thermoguard Fire Varnish System expands to create an insulating barrier, protecting timber surfaces from flames, heat and oxygen and suppressing emission of deadly smoke & gasses.

Specification and Application

Prepare and apply – (INTERIOR)


Available Pack Sizes

Applicators should also refer to instructions on product containers.

Previously Varnished and Stained Surfaces or Wood Preservers

The Thermoguard Fire Varnish System can be applied over firmly adhered standard clear varnish. For existing stained varnishes, stain coatings, old fire coatings or if in doubt, contact our Technical Department on 0113 2455450.

  • If preservatives are required, use rapid drying clear non waterrepellent grades**.
  • For tanalised or other preservative treatments, contact our Technical Department.

**Allow adequate time for stain or preservative fluids to escape before applying the Thermoguard Fire Varnish System.

Fire Test Standards and Certification

  • BS EN Class B s2 d0
  • Class 1 and Class 0

Note - For 30 or 60 mins Fire Resistance see Thermoguard Fire Varnish 30 & 60 Minute System.

For fire protection to doors, see Fire Door Upgrade Kits

We will issue a Certificate of Supply upon request for each correctly specified project for Insurance, Fire and Building Control Authority and Client Records against proof of purchase.

NEW Fire Regulations and Tests Explained

  • The new fire standard BS EN test lasts 20 mins. with airflow replaces the old BS 476 tests which lasted 10 mins and restricted airflow.
  • The new standard for flamespread and heat release Class B replaces Class O.

The new BS EN tests also monitor -

  • Smoke & Gas “s” – s1 + s2 are none or very low & compliant levels, s3 moderate , s4 high smoke.
  • Flaming Droplets or Airborne particulates – dO is none, d1 some, d2 + d3 moderate > high levels.

IMPORTANT FIRE PRODUCTS NOTICE: The information displayed on this website should be used as a guide ONLY and our Technical Department should be contacted to obtain a tailored specification and any advice necessary before you place an order for fire protection products. Fire protection products are non-returnable except in accordance with Condition 8 of the Terms and ConditionsWe will not be held liable for any resulting damage to property, human life or monetary costs incurred due to the incorrect specification you have prepared or use of fire protection products caused by your negligence, including your failure to have contacted us to obtain the relevant advice/specification.

It is your responsibility to read the Product Data Sheets (available below) before you place an order and prior to application of the product. The content of this website is our best recommendation and is not advice. Coverage rates quoted are approximate, you agree that coverage depends on the condition of the substrate, surface absorption, texture and application method. We ALWAYS recommend a trial area is coated to ensure the product meets your requirements before use.

Product Details

Data sheet

Brush, Roller, Spray
Supplied in pre-measured packs to apply 1 coat to 20m² or 40m²
Touch Dry
8 Hours

Customer agrees that before placing an Order, Customer has read and understood the most up to date Product Data Sheet for the Product. Where we have access to the Product Data Sheet from the manufacturer, we will either provide a copy on request, or include a link to the Product Data Sheet available on the manufacturer’s website. Customer further agrees that we have no liability for any errors or omissions contained within the Product Data Sheets. For more information, please see our Terms & Conditions of Sale.

questions John McGhee on 2019-11-16 14:48:56

If Thermoguard clear varnish is to be applied over existing varnish on wood, does it still need the Base Layer ?


Yes. Varnished, sealed or non-porous wood should be abraded thoroughly with medium grade silicone carbide abrasive when dry to provide a good key.

questions Hannes on 2019-09-02 17:14:42

How long will the exterior system withstand leaching, in how many years should the system be over coated and do you provide system for overcoating


We would need to know some more details of the application, i.e. timber type, level of fire protection, environmental exposures, etc. Please contact our Technical Team on 0113 2455450 (option 2) or [email protected] to discuss.

questions Brian Hepworth on 2018-03-06 07:47:38

Good morning. Can your clear varnish 2 coat system work on plywood that has been painted with acrylic paint (various colours) and still be classed as fire retardant?


No, clear fire retardant systems can't be applied over previously painted surfaces. Certain clear fire retardant systems can be applied over existing stains and varnishes but not opaque paints. To upgrade previously painted surfaces you should use something like Thermoguard Timbercoat BS Class 1/0 & EN Class B System or Thermoguard Timbercoat 30 & 60 Minute System in the colour and finish of your choice.

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