How and Why to Protect Structures with Intumescent Paint for Wood

intumescent paint for wood prevents burning

Intumescent paint for wood increases fire safety in buildings

Wood is a naturally beautiful and strong material used in interior and exterior design as well as structures of low buildings. However, the material becomes compromised when exposed to fire; heat and flames. Intumescent paint for wood is one method of protecting wooden surfaces from the effects of fire, allowing more time for evacuating a burning building and for the fire department to minimize the damage. Intumescent paint for wood also makes it possible to use wood in constructions of higher rise buildings while complying with building codes and fire safety regulations.

In this article we will look into the intumescent coating for wood used for fire protection in industrial applications and at home; whether you are looking for intumescent paint for wood to comply with building codes or are interested in upgrading fire safety at home you have come to the right place: here you will find learn all you need to know about intumescent paint for wood as well as manufacturers, suppliers and product.

How intumescent coatings for wood work

Intumescent coating is a type of fire protection coatings; the term ‘intumescent’ refers to the technology that allows intumescent paint for wood to protect the surface. The Intumescent coatings for wood swell and form a protective char layer when exposed to extreme heat. This char is a poor conductor of heat and thus insulates the underlying surface and so postpones the point at which the fire affects the properties of the structure.

The standards regulating the use of intumescent paint for wood

The protection that can be achieved with intumescent paint for wood is dependent on the coating, substrate and dry film thickness; the thicker the coating is applied the longer it protects in case of fire. Which coating you should choose for your project is defined by standards which regulate the required fire resistance for different types of buildings.

The standards for intumescent paint for timber are based on so called flame spread rating which measures the materials contribution to letting the fire spread. Additionally, the material’s contribution to smoke creation can be tested. In the USA general testing methods are according to ASTM E84 (UL 732) for building materials and ULC s 102.2 for floors. The standards result in 5 classes of fire resistance: from A to E, class A being the most resistant. 

3 ways to apply intumescent paint for wood

Intumescent paints were originally developed for metal structures, however, today they are suitable for softwoods, hardwoods, even chipboard and MDF, in both interior and exterior settings, the exterior intumescent paint commonly has a higher fire rating. The products for wood exist as clear and pigmented paints and varnishes as well as wood preservatives which soak into the wood. Intumescent paint for wood can be divided into onsite and offsite applications as well as products for home applications.

Intumescent paint for wood applied in a restaurant interior

An opaque intumescent paint for wood applied on wooden structures and a clear system on interior walls and floor.

  1. Offsite/ prefabrication: industrial intumescent paint for wood is often applied as part of the wood processing (prefab.) in order to cover as great area as possible, and guarantee optimal protection. The prefab intumescent coatings for wood are class A fire rated and protect for up to 120 minutes.
    Product example: TEKNOS Teknosafe 2407-00
  2. Onsite: the onsite applied intumescent wood coatings are applied on wooden surfaces as the first coating or on a special primer which enhances adhesion. These coatings belong to class A or B and protect for 60 to 120 minutes depending on the building’s requirements.
    Product example: Sayerlack (Sherwin Williams) and Envirograf intumescent varnish for wood
  3. At home: the consumer intumescent paint for wood exists in two types; one that can be applied to previously painted substrates and another that is suitable for direct to wood applications. The consumer products range from class B to C and protect for 30 – 60 minutes.
    Product example:  Fire Retardants Inc. Burn Barrier 20-20 

Tip: any intumescent wood paint can be topped with a compatible fire retardant wood coating to increase the fire resistance. In such a system the intumescent paint for wood is a base coat (usually applied on a primer) which provides the best protection. The top coat however, keeps the flames at distance to postpone the swelling reaction extending the time the wood remain unaffected.

Intumescent coating for wood application and certification

Applying intumescent preservatives is often an industrial wood pretreatment process done prior to the wood arriving at the buildsite. However, if the used wood is not pretreated with intumescent products, it is a smart move to apply the coating once the structures stand. Applying intumescent paint for timber at home is a DIY project; the coatings are usually 1 component, easy to apply systems which do not need diluting.

For public, industrial and commercial buildings, intumescent paint should always be applied by a certified applicator, to make sure you get the rightful guaranty for the product and the job done. This may come in handy especially with insurance policies or if you ever need to claim insurance.


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