Fire protection of wooden structures: choosing a fireproof impregnation

Recommendation points

• Classification of fire retardants (OS)
• Operating principle. Overview of types of OS for wood
• Some rules for selection and processing

Increasing the fire resistance of wooden structures means increasing the fire safety of a building. This problem can be solved for low-rise buildings by treating wood with chemical and paint fire retardants. Let’s talk about fireproofing impregnations and paint materials.

Despite the indisputable advantages of wood as a structural material, it has a number of significant disadvantages, including, along with susceptibility to decay, its property is easily ignited and burns quickly. This means that wood structures, even after removing the flame source, are capable of burning for a long time. Nevertheless, one should not abandon the use of environmentally friendly and relatively inexpensive wood products in construction. Think about how to protect them from hazards. To ensure the fire safety of a building, the fire resistance of its structural elements can be increased using known methods..

Despite the fact that the norms (SP 54.13330.2011, NPB 106–95) establish the obligatory fire-retardant treatment of roof frames made of combustible materials only for buildings with a height of three floors, do not underestimate the importance of increasing the fire resistance of load-bearing and enclosing structures of log cabins, houses made of profiled or glued timber, one- and two-story attic coverings.

The use of specially selected directional compositions will increase the resistance of wood materials to fire and reduce the speed of flame propagation.

Classification of fire retardants (OS)

GOST R 53292-2009 provides a classification of fire retardants, simplified schematized in the figure:

Depending on the ability of OS to reduce the combustibility of wood, they are divided into two groups according to fire retardant efficiency:

Operating principle. Overview of types of OS for wood

1. Lacquered OS are used most often for processing furniture, decorative items made of solid and recycled wood, and finishing elements. They are classified by wear resistance, water repellency, UV resistance. The advantage of using varnish OS is the preservation of the wood structure, giving it a gloss or matt finish, and the presence of a protective film. For floors, railings, steps and other elements subject to abrasion, special types should be used, such as parquet varnishes..

For interior work, NEGORIN-LAC can be used, the CERAM-PROTECT product is more versatile..

From a similar line of products from other manufacturers, OZL-SK, OZL-1 (KF-FA) LLC KOVEX, Stabiterm-107, Shield-1 are known.

2. The principle of operation of fire retardant paints and thermally expanding compounds is the multiple thickening of the coating with increasing temperature, the formation of a foamy layer that prevents the rapid heating of the element. The advantage of these types of products is additional protection of wood from moisture. The typical prophylaxis period for flame retardant paints is usually 1 to 5 years. Obtaining hardly combustible or hardly combustible wood with the help of one means, as a rule, is achieved due to a different number of layers.

Popular OS of the considered type are “Piroplast-HW100”, “Akvest-01”, “Pyrex”, “VUP-2D”, “Phoenix DB”, DEFENDER-M.

3. Constructive fire-retardant wood treatment in its action is similar to the principle of operation of the OS increasing in volume, and consists in providing thermal insulation of the processed element. Such coatings include pastes, plasters, plasters, tiles and sheets. Examples are plasters with the addition of perlite or vermiculite, Ograx-V-SK paste. The application of pastes and coatings should be done regularly, at least every two to three years..

4. The chemical method of protection is the use of impregnating OS, which can deeply penetrate into the volume of wood, for example, when soaking in baths and applying under pressure, or superficially, when processing with a brush.

Such products include “Fire retardant-Amidophosphate KM” LLC “KOVEX”, the composition “PP”, “VANN-1” “Neohim”, “Pirilaks Terma”, “Pirilaks SS-20”.

5. The combination of fire protection methods is becoming more and more popular. So, fire-retardant coatings allow, along with an increase in the fire resistance of structures, to provide protection against fungal infection, rotting and mold. There are a wide range of names on the market, for example, “SENEZH Ognebio”, NEOMID 450 and compositions of MS, KhMXA, “Iceberg-301”, “OK-GF”, “ZOTEX Biopirol”, “Asfor-Bio”, “Attik”, means from the Pirilax range.

It is possible to increase the efficiency of fire protection by the simultaneous use of impregnations and the application of varnish and paint OS. It is recommended to cover structures made of wood for outdoor use in addition to easily washable impregnating OS with film-forming agents.

The results of the experiment of using a combination of agents with different principles of action can be found in the video:

Some rules for selection and processing

The choice of OS for wood is determined by the conditions of its operation. For a closed unheated room, less significant fluctuations in temperature and humidity are characteristic than in the open air, and in heated rooms a positive temperature and a relative humidity of no more than 70% are provided.

Estimate the duration of the OS warranty protective effect, check for certificates on them. If you intend to use a combination of impregnating and painting agents, check their compatibility, not every fire retardant paint can serve as a finishing layer on wood pre-impregnated with OS. For wood elements exposed to sunlight, use UV-resistant OS. In baths and saunas, due to the special temperature and humidity conditions, you should use products specially designed for such conditions.

Carefully calculate the consumption of the product: specify on the label the required number of layers for the desired group of fire retardant efficiency.

Wood processing should be carried out at a moisture content of no more than 70% and a temperature of at least + 5 … + 10 ° С on a dry and free from dust and dirt surface. When covering a previously painted surface, remove all remnants of previous paints and varnishes from it, clean and dust..

The main processing methods are:

• application with a brush, roller or spray gun in several layers;
• soaking in cold baths or after preheating the product.

Do not neglect safety precautions. Ensure good ventilation when handling toxic materials indoors, wear a respirator, goggles and rubber gloves.

Having made the decision to carry out fire protection of wooden structures in your home, be prepared for its regular, almost annual renewal. Such measures will not only reduce the risk of fire or contain a sudden-onset fire, but most importantly, will ensure that you and your family can safely leave the building in the event of an emergency..