Even if the roof structure is equipped with an ideal under-roof ventilation system, the roof always remains an element of the house exposed to moisture. Outside is precipitation, and from the inside - air vapor rising from warm rooms premises and condensation in the upper part of the house, in particular on load-bearing structures roofs - wooden rafters. Open wooden structures are primarily exposed to constant exposure to moisture - lower crowns from logs and timber, frame elements. This is especially true for areas with a humid climate.
A humid environment promotes the proliferation of microorganisms and insects. Therefore, mold and fungi can form on wooden surfaces, contributing to wood rotting. In addition to these microorganisms, wood-boring insects can choose roof rafters as a favorable habitat. Therefore, first of all, wooden roof structures require bioprotection - a treatment that is safe for people and animals, but prevents the proliferation of insects and microorganisms chemical agent.
And of course, the second enemy that lies in wait for the roof rafters is fire. Wood is a flammable material. And this should not be forgotten, especially in areas with arid, hot climates. Therefore, for complete confidence in the fire safety of rafters, it is also recommended to treat them with fire retardants - fire protection agents.
Which product should I choose to treat rafters?
Modern market offers many effective means for bio- and fire protection of wooden structures. However, if you use them separately, the wood must be processed in several stages. First, an antiseptic is applied in several layers, and only then - fire retardants. As a result, the process becomes quite lengthy and labor-intensive. Therefore, the most modern scientific development in the field of protecting wooden surfaces is universal means, which contain both surfactants that prevent the proliferation of microorganisms and insects, and salt solutions that, upon contact with fire, form a resistant fire-retardant film. As a result, wood changes its properties and becomes a highly flammable material.
One of the most modern universal products is TECHNONICOL Fire and Bioprotection of Wood (10 and 20 l). The impregnation contains a complex of highly effective biocides and fire retardants. The product is safe for people and animals, does not contain arsenic and chromium compounds.
It is ideal for protecting wooden structures used both indoors and outdoors. However, the external elements should not come into contact with the ground and be exposed to precipitation.
Advantages of TECHNONICOL wood fire protection
- The product is applied once at a rate of at least 500 g/m². It is at this level of impregnation that wood becomes a material that is difficult to ignite and acquires the properties of substances that belong to group I of fire protection.
- Impregnation provides fire protection for more than 7 years, and bioprotection for 20 years, which eliminates the process of rotting under the fire retardant film.
- The structure and properties of wood do not change during processing; the impregnation is not subject to aging, leaching and salting out.
- The product can be applied both for the first time and on previously treated surfaces. After this, the wooden surfaces can be glued together and covered with any paint and varnish materials.
Application rules
- Wooden surfaces need to be cleared of shavings, sawdust, dust and old paint. If the wood has already been infected with mold, which has affected the color change, it is necessary to use wood bleach before applying the impregnation.
- If the product is used on a finished roof structure, then a roller, brush, or sprayer are used. At the same time, it is applied generously and evenly.
- If the rafters have not yet been installed, it is better to immerse them in the solution for 30-60 minutes. This method is convenient for simultaneous processing of a large number of wood parts.
- Processing must be carried out at a temperature not lower than +5°C. In this case, it is necessary to prevent water and precipitation from coming into contact with the treated surfaces.
- When using impregnation, you need to protect glass surfaces. It is mandatory to use personal protective equipment: goggles, mask, gloves. If the solution gets on your skin or eyes, you need to rinse these areas. big amount water.
Make sure your roof rafters serve you well long years. Applying a universal fire protection agent to wooden structures will help you significantly save on roof repairs during its long-term operation.
Rot is nothing more than the effect of fungi on wood fibers; these rather tenacious microorganisms absorb the organic matter contained in the tree in incredible quantities, causing visual effects familiar to many. There is no need to explain about fire; even a child knows how easily a log burns in dancing flames, beautiful and merciless to everything that can be used as fuel.
Therefore, when you are about to move on to the final part of building a house, namely, laying rafters and sheathing, analyze what threatens the lumber in the first place, based on the climate. So, excess moisture can become a favorable factor for the occurrence of fungus, and frequent aridity in the region often leads to fires (overdried wood ignites like gunpowder). Based on the analysis, it will be easier to decide how to treat rafters as impregnation and coating, prioritizing the use of substances.
Wood is treated with antiseptics and fire retardants, and the sequence of their use is dictated by the degree of probability of rot or fire in the structure. First of all, impregnation is used, penetrating deep into the structure, then comes the turn of coating. Only one composition can be used as an impregnation - either a fire retardant or an antiseptic; it will not be possible to impregnate wood fibers twice.
Therefore, if you are afraid of rot, impregnate the lumber with an antiseptic, and if you are afraid of fire, use fire retardants. As a coating, of course, a substance with different properties than the impregnation will be used, that is, if a fire retardant was used, the surface is treated with an antiseptic.
How are rafters processed?
How difficult it will be to process the rafters depends on whether they are already installed, or whether you are just planning to start building the roof frame. It is logical that in the first case, deep impregnation will become almost impossible, unless by using special devices(impregnation under pressure). If the house has already been built “under the ridge”, be prepared to pick up a roller and a dowel. If the rafters are still lying on the ground and you are only planning to assemble them into a roofing structure, do not rush, it is better to carry out a full impregnation.
In order for the antiseptic or fire retardant to penetrate deeply into the structure of the wood, it is advisable not just to treat it from the outside, even in generous portions, but to completely immerse the rafters in the composition of your choice. To do this, a trough is knocked together, the length and width of which is slightly larger overall dimensions rafters, from the inside it is covered plastic film, which is aimed with a construction stapler.
An impregnating substance is poured into the resulting container, into which the prepared rafters are immersed alternately for 1-2 minutes. The trough can be replaced with a shallow ditch dug and covered with polyethylene. After impregnation, the rafters are installed in such a way that there is air access to all four planes, allow 1 day for drying, this is quite enough.
Various cuts, grooves and end parts of the rafters are additionally processed manually, since in these places the wood fibers are especially vulnerable.
Surface coating of rafters is done with a roller, paint brush or paint brush. The substance intended for external coating of wood forms a thin but quite durable (from 2 to 8 years) film. The substances contained in the antiseptic prevent the appearance of fungus on the surface and penetration deep into the fibers, and the components of fire retardants have two types of action: melting and decomposition with the release of gases.
The former (salts of phosphoric or silicic acids, salts of boric acid) upon contact with an open flame create a melted film, which significantly slows down the heating of wood, and the latter, by releasing non-flammable gases (sulfur dioxide or ammonia), dilute flammable gases and repel oxygen from it, preventing ignition. Fire-resistant plaster can be used as a primitive fire retardant.
Universal impregnation for rafters - myth or reality?
Protecting rafters and sheathing from all sorts of misfortunes means repeatedly treating the wood with various compounds, which involves considerable labor costs. But I would like to simply dip the future element of the roof frame into a universal composition once and, after a short drying, install it in its intended place. But is there such an impregnation for rafters that will protect you from fire, protect you from fungus, and repel woodworms?
Yes, of course, such compositions exist; manufacturers of impregnations and coatings for wood have been developing universal products for a long time, and there has been some success. The components of such compositions include solutions of salts that prevent wood from burning, as well as various substances(mostly surfactants), which interact with antiseptic additives and resist the occurrence of fungus.
However, universal compositions have one unpleasant quality - you never know after processing whether the impregnation was done well enough. And even if you want to play it safe and continue processing the rafters and sheathing, nothing will come of it, since the surface has already appeared protective film.
At the same time, the service life of the components can vary greatly, for example, antiseptic additives are designed for 2 years of service, and the component responsible for fire-resistant properties will last 10 years. And this will mean that the wood, being protected from fire, will be vulnerable to the appearance of fungus, which, having formed rot in the structure of the rafters, will also compromise fire resistance. So is it worth using complex formulations?
The roof truss system is a wood material that is easily destroyed upon contact with moisture and quickly ignites in the event of a fire. How to treat rafters to extend their service life and prevent the formation of mold microflora. Which of the formulations available on the market is most effective? This depends on the type of wood and the prevailing climatic conditions. If it’s humid, you need protection from water; if it’s hot, you need to protect the wood from fire.
What should be the composition
Any product you decide to use for coverage rafter system, must meet the following requirements:
- penetrate deeply into the structure of wood fibers;
- do not contain copper sulfate, potassium bichromate, arsenic, chromium;
- dissolves well in water, but does not wash off from the tree;
- effectively protect floor beams and sheathing from mold, rot, fungus, and prevent fire.
After this, it is worth deciding what threatens the rafter system more – rot or fire. For humid climatic conditions, an antiseptic is chosen that will penetrate deeply into the wood, and after that it is additionally coated with a fire retardant. The fact is that wood can only be impregnated once. Strengthening the properties of wood to resist the formation of rot or fire depends on which composition is applied first.
What are the types of antiseptics?
Antiseptics for floor beams and sheathing may have additional decorative effect. The composition of the products includes alkyd resin, which gives the wood specific color. For the rafter system, water-soluble antiseptics are most often used. They have a number of advantages:
- penetrate deep into the wood structure;
- they are easy to apply to elements of the rafter system;
- dry quickly and allow the wood to breathe;
- form a moisture-proof film on the surface of the wood.
High-quality antiseptics must have antimicrobial (biocidal) and antifungal (fungicidal) properties, and also provide reliable protection from insects – insecticidal properties.
Water-soluble substances predominantly contain sodium fluoride and silicofluoride, a mixture of borax and boric acid, pentachlorophenol, a mixture of zinc chloride with sodium (potassium) chromium. The compositions are toxic only to microorganisms and are completely harmless to humans. There are also products soluble in oil, petroleum products and light solvents.
Methods of applying antiseptics
Impregnation (surface impregnation with an antiseptic) is performed by complete immersion wooden elements into the composition or by applying the substance with a spray bottle / regular brush. For immersion, use a special bath, trough or even a ditch, after lining the container with plastic film.
The immersion time of the material depends on the specific antiseptic. Typically, the manufacturer indicates on the packaging 30-60 minutes for wood of small and medium sections. When immersing large trusses, for example, for roofing made of natural tiles, the impregnation time is increased to four hours. After drying for 24 hours, all ends of wooden structures are treated.
When treating with an antiseptic manually by spraying, spraying or painting, the efficiency of penetration of the composition deep into the wood is noticeably reduced. Although this method requires small quantity antiseptic composition.
The coating is carried out in several layers with an application interval of about half an hour.
The most popular antiseptics
Has proven itself in practice modern remedy Senezh. This antiseptic can be used to treat the roof, wooden sheathing, floor beams. The composition is presented in the form of a ready-to-use solution on water based. Its advantages:
- bioprotection for a period of 30-35 years;
- type of composition – difficult to wash out;
- chemical bond with wood;
- penetrates deeply into the fiber structure without increasing hygroscopicity;
- allows the tree to breathe;
- has a decorative effect.
The recommended consumption is 250-300 g/m. cube when applied without immersion, 60-80 kg/m. cube when soaking. Senezh penetrates deeply into floor beams and other elements, forming a two-level protective barrier. Prevents the development of fungi and mold microorganisms, insects. The manufacturer produces various series of antiseptics - Ultra, Bio, Thor, Sauna for specific wooden structures.
Estonian-made Pinotex Impra is highly effective. Suitable for bioprotection of floor beams, sheathing, mauerlats, rafters. It is a water-based antiseptic with an alkyd binder. Deeply absorbed into the wood surface, provides good protection from rot, blue stains, mold.
The consumption of the substance ranges from 85 to 200 g per square meter, depending on the wood processing - sawn or planed. Pinotex Impra cannot be used for elements of the rafter system already affected by microorganisms, unlike the Senezh composition.
The product produced in Russia, Drevotex, is used to protect wood material from the formation of rot and mold. Main characteristics:
- effectively protects floor beams and boards from exposure to atmospheric moisture;
- the bio series is suitable for the prevention of healthy wood material, the anti-mold series is used for wood affected by focal microorganisms;
- type of impregnation – difficult to wash out, allows the wood to “breathe”;
- bioprotection period of the rafter system complex means Woodex is about 30 years old;
- product consumption is 250-350 g/sq.m. m when brushing and 200 kg/m. cube when immersed.
The product can be applied to new wood or as a treatment for existing roofing structures.
When choosing antiseptic compounds for floor beams, sheathing boards and mauerlats, it is necessary to pay attention to the moisture content of the wood, since not all antiseptics are suitable for wood with a moisture content of more than 20 percent.
Application of fire retardants
Fire protection is designed to give wood material additional qualities - fire resistance, reduced flammability. If you decide that the likelihood of a fire is higher than the possibility of rotting truss structure, first of all, all wooden fragments of the roof should be treated with fire retardants.
They are classified into the first and second efficiency groups. The products of the first group provide fire protection for 5-7 years, so they are more effective. Most fire retardants are based on ammonium phosphates and sulfates, borax, boric acid and combinations of these substances.
All fire retardants are divided into:
- Impregnations are solutions of salts that are applied manually or by immersion.
- Coating fire retardants have a paste-like consistency.
- Varnishes are used for decorative purposes. Their use on the roof is unnecessary.
- Paints form a thin protective film on the surface.
Most often, to protect floor beams and rafters, impregnation is used, when the fire retardant will serve as the main protection, and coating, if the fire retardant is applied to the antiseptic. The methods of coating with fire protection are identical to the application of antiseptics. Available on the market big choice compositions of the first and second categories. Neomid is very popular.
Since the composition has received mass positive feedback buyers, you can take a closer look at its properties.
Neomid 530 – fire protection
The product is suitable for any type of wood surface - sawn or planed floor beams, boards, rafters, sheathing. Main advantages:
- fire protection for ten years;
- has antiseptic properties;
- does not contain toxic substances and formaldehyde;
- does not interfere further processing wood;
- does not change the hygroscopicity of the material;
- supplied ready to use;
- made on a water basis;
- in terms of danger to humans, it occupies the same category as household chemicals, - not dangerous.
Neomid compositions are available in different series. Some products are designed to protect floor beams and other elements of the rafter system from insects, rot, blue stains, and are used as wood bleaches. Neomid 530 is an effective fire protection that is currently the most popular.
Before processing rafters, you need to choose the right protection priority. The composition that is applied first will be the main one. The second substance will perform an additional protective function.
How and with what to treat rafters and sheathing - choose an antiseptic
For the manufacture of the rafter frame, in most cases, wood is used, which is susceptible to moisture and is very flammable. These factors must be dealt with, since restoring a destroyed rafter system will require much more effort. This article will discuss how to treat rafters and sheathing to protect them from fire and moisture.
Requirements for protective compounds
All products used to process rafter systems must meet the following requirements:
- Possibility of deep impregnation of wood;
- Absence of copper sulfate, potassium dichromate, arsenic or chromium;
- The ability to dissolve in water, but at the same time stick well to the surface of the wood even when it gets wet;
- Ensuring reliable protection of rafters and sheathing from various biological factors and ignition.
When deciding what to impregnate the rafters with, you must first consider what affects the rafter system the most. If the region where the building is located is characterized high humidity air, then the most relevant will be antiseptics that need to be soaked into the wood. The sequence of processing is important - the composition applied first works much more efficiently than subsequent layers.
Types and characteristics of antiseptics - what is the best treatment
Most antiseptics for rafter systems can increase decorative properties structures when applied due to the alkyd resin included in the composition, which changes the shade of the wood.
The most popular antiseptics are water-soluble, which have the following advantages:
- Deep penetration into the wood structure;
- Easy to apply and quick to dry;
- Possibility of normal ventilation of wood;
- Creation of a moisture-proof film on the surface of wooden elements.
Regardless of the characteristics of the antiseptic, it should protect the wood well from germs, insects and fungi. In addition, any antiseptic for rafters must be harmless to human health.
Methods for applying antiseptic to rafters and sheathing
Treatment of the rafter system with an antiseptic is carried out by the impregnation method, which can be performed by completely immersing the elements of the rafter system in the composition or by surface application of a protective agent.
To process wood using the first method, you need any large container - a bathtub, a trough or a regular pit. The main thing is to completely cover it with plastic wrap before diving. The time required for deep impregnation of wood varies widely: thin wood can be impregnated in half an hour, while processing large structures can take up to four hours. When the impregnation of the rafter system is completed, you need to dry the part for 24 hours and process its edges.
All other methods - spraying, spraying or painting - are significantly less effective. But processing the rafter system using these methods will be somewhat simpler, and much less antiseptic will be required. In order for the treatment to be of high quality, the coating must be applied in several layers, allowing each of them to dry for at least half an hour.
The most popular antiseptics
One of the most common protective agents is the roof antiseptic Senezh, which has many advantages, including:
- Long service life, reaching 30-35 years;
- Reliable coating and good resistance to washing off;
- Excellent penetration into wood;
- Ensuring normal ventilation of the tree;
- Good decorative properties.
The water-soluble composition Senezh is excellent for processing wooden elements of the rafter system and sheathing. Penetrating into the wood structure, this impregnation for rafters provides two-layer protection against fungus, mold, insects and various microorganisms. Senezh product is available in several series - Ultra, Thor, Bio and Sauna, each of which is suitable for use in specific situations.
Another good remedy, suitable for processing the rafter frame - Pinotex Impra (Estonia). This antiseptic is made on the basis of water, and an alkyd substance is used as a binder. Pinotex quite effectively protects wood from various biological damage. The main disadvantage is that treating rafters with Pinotex antiseptic is impossible if they are already damaged.
A good alternative to foreign products is the domestic antiseptic Drevotex, which provides reliable protection of the wooden elements of the rafter frame from moisture and biological factors. This product is produced in several series: the Bio series is used to treat new boards, and the compositions of the Anti-Mold series are designed specifically for restoring wood that already has lesions.
Drevotex practically does not wash out when moisture gets on it and does not interfere with the passage of air to the wood. The service life of the applied coating can reach 30 years. If you approach the issue of choosing a series wisely, then this product is perfect for any situation. Before choosing, you should check the wood for humidity - many antiseptics are not suitable for treating wood with a humidity above 20%.
Types and characteristics of fire retardants for the rafter system
Fire retardants are agents that increase wood's resistance to fire and reduce flammability. When deciding whether to treat the rafters with a fire retardant, it is worth understanding which factors will have a stronger impact on the frame. Most often, these products are applied secondarily, but if there is a high risk of fire in the rafter structure, then they should be used as the main impregnation.
All fire retardants are divided into two effectiveness groups. The first group is more efficient and durable - these products provide fire protection for about 5-7 years. The second group, accordingly, is somewhat less effective.
Depending on individual characteristics, fire retardants are classified as follows:
- Impregnations. These substances are salt solutions that, through immersion or manual processing applied to wood.
- Lubricants. This category of fire retardants is distinguished by its paste form.
- Lucky. Varnishes are most often used as decorative coating, therefore, their use for processing rafters will be inappropriate.
- Paints. These products create a thin film on the surface of the wood, which provides protection from fire.
If you plan to use a fire retardant as the main protective agent, then it is worth using impregnations. When applying a fire retardant over an antiseptic, coating compounds are best suited. The technology for treating wood with fire retardants is no different from the technology for applying antiseptics.
Fire retardant Neomid for treating wooden roofing elements
One of the most popular means used for fire protection is Neomid, suitable for processing all types of wood. There are many varieties of Neomid - in addition to increasing fire resistance, they can act as antiseptics, protecting wood from the most typical influences.
The list of advantages of this product looks very impressive and includes the following qualities:
- Long service life (up to 10 years);
- Presence of antiseptic properties;
- No toxic or hazardous substances to human health in the composition;
- If necessary, the wood can be treated over Neomid;
- Wood after treatment does not change the degree of moisture absorption;
- The water-based protective composition Neomid can be used immediately after purchase, without additional preparation.
Conclusion
Before processing the rafter frame, you must decide how to process the rafters first. The composition applied first affects the characteristics of the wood much more than the next layer of protection.
What antiseptic to treat the rafter system with?
Different types of wood resist rot in different ways, and sometimes it is necessary to artificially enhance certain properties of the material. Coating with special compounds is therefore necessary to protect against both fungus and fire. How to treat the rafters first, and what to choose as an addition, must be decided immediately. After all, it will not be possible to soak them twice: first with an antiseptic, and then with antipyrine, which protects them from flames. Based on the climate, it is necessary to determine whether rot or fire primarily poses a threat to the lumber. For impregnation, a basic composition is selected that penetrates deep into the wood fiber. Then it is coated with an additional composition.
Treating rafters with an antiseptic is necessary to ensure that the wood lasts longer.
Compositions for treating roof trusses
As a rule, in areas that are not too dry, wood suffers more from fungus. Rafters are processed taking into account their condition. Usually an aqueous solution of some product is used. However, for wood already infected with fungus, it is necessary to use special disinfectant impregnations. To protect against beetle larvae, they are also selected special compounds. At the same time, it is unsafe to treat rafters with several drugs at the same time, because it is unknown how they will interact with each other.
Do not use chemicals such as copper sulfate or potassium dichromate. They not only change the color of the tree, but are also quite strong poisons. Now in construction stores there are many compounds that can effectively impregnate a rafter beam: Senezh, Drevotex, Olympus, Rogneda. They are environmentally friendly, non-toxic and provide more lasting results. Some of them are produced in series designed for specific types of disinfection. from beetles, mold, mildew, and also especially for end parts. This allows the entire rafter system to be completely protected.
In industry, the consumption of the substance is about 3 kilograms per cubic meter of wood. It is not used in such quantities in everyday life. The product is diluted with water in a ratio of one to nine. When applied in two layers, no more than 200 milliliters of the original chemical are consumed per square meter of surface. Although experts believe that truly reliable treatment of rafters should be carried out in 5-8 layers.
We process the rafter system correctly
To make wood last longer, you can treat it with olive oil.
In industry there is a fairly complex, but very efficient technology with preheating of wood. Then, immersed in a cold solution, it quickly cools down and a reduced pressure is formed in it. This creates conditions for deeper penetration of the disinfectant composition. The product is kept in a container with an antiseptic for up to several hours. This operation It is also produced in autoclaves at high pressure, and then excess chemicals are removed using a vacuum method. In factory conditions, it is possible to achieve penetration of the composition to a depth of up to 15 mm.
The treatment can also be carried out at home. Often you have to do it in an already built house, covering the rafter beam with mortar using a roller and brush. This surface coating forms a protective film that will last from 2 to 8 years. Deep impregnation in this case can be carried out only with the help of special devices or under pressure. Therefore, if the assembly of the structure has not yet been completed, it is better to completely immerse its components in the product.
First you need to knock together a trough and line it from the inside with plastic film, securing the edges with a stapler. It should be slightly larger in length and width than the trusses that are immersed in it. For large structures, you can dig a ditch and also cover it with polyethylene. The container is filled with impregnation and the rafters are alternately immersed in it for 30-60 minutes. Dry them for 24 hours, while ensuring air access from all four sides. It is advisable to perform this procedure twice.
However, this method is good if the wood moisture content is no more than 30% (for pine, no more than 25%). More raw material, as well as the processing of rafters with a fairly large cross-section, for example, for heavy tiles, require immersion in the solution for a long time, on average up to 4 hours. Otherwise, the protective layer will be too thin and can be washed away by rainwater.
In addition, the ends, grooves and other cuts must be additionally coated with the product manually, using a paint brush or paint brush. You can also apply the solution using a spray bottle. And, no matter how the rafters are processed, it is necessary to handle the impregnating layer with care and not violate its integrity. Damage may occur from contact with sharp-edged instruments or from being dropped from great heights.
Is it worth treating rafters with universal means?
Of course, repeated processing and coating. the process is labor-intensive. And there is always a temptation to bathe the future frame element in a bath with a universal solution just once, dry it and install it in place. Indeed, such impregnations have been developed and are already on sale. They contain, along with an antiseptic that protects against fungal infection, a solution of certain salts that protect against fire.
But the downside of such universalism is the impossibility of determining how well the material has been saturated. And after drying, it will not be possible to continue processing, since a protective film has already formed on top. In addition, the timing of exposure may differ significantly various additives. For example, the effect of antiseptics is designed for 2 years, and antipyrines - for 10 years. Then fungus may develop in the wood protected from fire by these means. However, it is impossible to re-soak it with a disinfectant solution, since it is still covered with a protective film. So it is better to abandon such versatility in favor of quality.
Wooden rafters have been used in construction since ancient times. They have excellent performance characteristics and are easy to process. You should take care of the means for treating the rafters long before you begin assembling the roof frame.
Why do you need to treat rafters?
The fact that wood is susceptible to rot is well known. Microorganisms that appear in it destroy the fibers, as a result of which the material loses its quality characteristics.
The strength of the rafters is also determined by the type of wood. In the construction of roof structures, in most cases, they are used coniferous varieties wood that easily ignites due to its high resin content.
For real evaluation negative factors, which can adversely affect the roof structure, an analysis of the characteristics of a particular region is necessary. At high humidity climate, the main danger is the possible rotting of wooden elements. In hot climates, the first thing to think about is protecting the structure from fire.
Here you will find out what it looks like and learn about the features of its installation.
If you are interested in how much it costs to repair a house roof and how to choose the right materials, take a look.
Different breeds trees differ in their degree of susceptibility to rot. The application of special compounds can protect against both fungus and mold.
What product should be used to treat the rafters first, and which ones can be chosen as an addition? This issue must be resolved in advance, since it is impossible to impregnate the material twice: first with an antiseptic composition, then with an antipyretic one to protect it from flame. This issue is also resolved depending on the climate. The impregnation should be a basic composition that penetrates deep into the wood fiber. After this, coating is carried out with an additional composition.
What should I impregnate the material with?
So, impregnations can be antiseptic and antipyretic. You can purchase wood already processed, but in most cases it is still sawed directly on site, so new cuts need to be impregnated.
Antipyretics
This group includes substances of the first and second efficiency groups. They can provide a certain percentage of weight loss of the processed wood material (up to 9 and 30%). Regardless of the quality characteristics of the rafters, regular checks of their condition are required. In case of non-compliance with the standards, restoration work must be carried out.
Fire retardant materials are of the following types:
Impregnations– are solutions of salts, the application of which is carried out in three ways:
- manual;
- immersion method;
- under pressure.
Coatings are mixtures of paste-like consistency.
Lucky used in cases where it is necessary to preserve the beautiful natural grain of wood.
Paints– when they are carried, an opaque thin film is formed on the surface.
It should be taken into account that fire retardant impregnations can be intended for both closed and open areas.
Antiseptics
The classification of antiseptics is somewhat different. They are purely protective and can have a decorative effect.
Group protective antiseptics is divided into the following types:
- easy to wash;
- difficult to wash out;
- washable.
Antiseptic compositions can be dissolved in oil, water, light solvents, and petroleum products. For construction, as a rule, water-soluble antiseptics are used. They have a number of advantages:
- dry very quickly;
- form a durable film on wood;
- allow the wood to “breathe”.
The basis of antibacterial impregnations with a decorative effect are alkyd resins. As a result of appropriate processing, ordinary pine can turn into any tree valuable breed. The impregnation contains a solvent, which ensures good adhesion and penetration of substances to a sufficient depth.
Which composition to choose?
In non-arid areas, the tree suffers more from the effects of the fungus. Rafters are processed taking into account their initial condition. Aqueous solutions of a certain agent are mainly used. But if the tree is already affected by fungus, it is necessary to use special disinfectant impregnations.
To protect wood from beetle larvae, special compounds must be used. It should be borne in mind that simultaneous treatment of rafters with several drugs is not entirely safe, since they can react with each other.
Today construction stores offer a large number of compositions, the use of which for impregnation of rafter beams gives excellent result. Drevotex, Senezh, Rogneda, Olympus have proven themselves well. They are distinguished by their environmental safety, non-toxicity and durability of the results obtained.
Some of these compounds are produced in series that are intended for different types of disinfection and different purposes:
- from mold development;
- from fungus;
- from a beetle;
- for processing the end parts of the building.
Complex processing makes it possible to fully protect the entire rafter system.
The consumption of the substance in industry is approximately three kilograms per cubic meter of wood. When used at home, there is no need for such large volumes. In these cases, the product is diluted with water in a ratio of 1:9. When applied in two layers, the consumption is no more than 200 ml ready-made product to process one square meter surfaces. However, this approach is not justified from a professional point of view: experts say that for reliable processing it is necessary to apply at least 5-8 layers.
Impregnation requirements
- The wood impregnation agent must be completely soluble in water and not contain chromium and arsenic compounds.
- It is very important that the impregnation does not wash off, since fixing the components of the product in the thickness of the wood is extremely necessary.
- A high-quality and correctly selected composition should reliably protect wood from destructive biological factors: fungi, microorganisms, insects.
- If necessary additional protection rafter systems from possible exposure to fire after installation is completed roofing An antipyretic is applied to it by spraying.
Basic methods of wood processing
Impregnation (or surface impregnation) of wood can be done in two main ways:
- immersion in protective composition;
- spraying with a spray bottle and applying with a roller or brush.
Features of the immersion method
Wooden elements are immersed in a special bath with protective agent. Treatment can be carried out with a cold solution, the temperature of which corresponds to the temperature environment, or hot - from 50 to 60 degrees.
The third method of impregnation is contrast. When using it, the wood is first immersed in hot impregnation, after which it is quickly transferred to cold impregnation of a similar concentration. The sudden cooling method enhances capillary suction. In a similar way, wood can be impregnated to a 20 percent moisture level.
Duration of the procedure
Previously, impregnation methods were divided into two types: long and short - the wood could be kept from several days in a cold solution to 15-120 minutes inside a hot one.
Today, wood processing has lost its relevance within a few days. Offered by the construction market the latest tools much more different high efficiency compared to the means of the previous generation.
If it is necessary to process wood maximum depth special devices are used with which the impregnation process is carried out under pressure.
Manufacturers of impregnation products must accurately indicate the method and duration of wood treatment in the instructions for use.
Material moisture
The moisture level of the wood has a significant impact on the duration of impregnation and its quality. The higher the moisture content of the material, the better it will be saturated. If it is necessary to process wood above the degree of natural fiber saturation (in the case of pine, this figure is 28-29%), it is recommended to use more concentrated solutions or increase the length of time the wood is in a bath filled with the composition.
The immersion method is successfully practiced by construction companies. The only limiting factor today is the parameters of the tank used for immersion, since the rafters are quite large structural elements.
Spraying, Spraying, Application Method
The distinctive properties of this method are simplicity and low cost. Its main advantage is the ability to impregnate ready-made structures. Disadvantages of this method:
- in terms of efficiency, it is significantly inferior to the immersion method: the depth of penetration of the composition into the thickness of the wood is only a few millimeters;
- the second significant disadvantage of spraying is that the hidden parts of an already erected structure cannot be processed properly.
- When using a less concentrated solution or applying an insufficient number of layers (for example, to save money), it is not possible to achieve a sufficient level of protection for the wood, as a result of which it is subject to deterioration over time.
- When using impregnation, you must follow the manufacturer's recommendations regarding the amount of solution and method of its application. You cannot limit yourself to applying two or three layers of a substance if five or six are needed.
Processing of the rafter system
The technology used in industry to preheat wood is quite complex. During the process of immersing a tree in a cold solution, it quickly cools down, which leads to the formation of reduced pressure in it. This ensures more deep penetration disinfectant composition. The elements are kept inside the container for several hours. A similar operation is also carried out in autoclaves under high pressure conditions, after which excess chemicals are removed using the vacuum method. When carrying out the procedure in a factory environment, the composition penetrates to a depth of 15 mm.
Processing can also be carried out independently. Very often there is a need to carry it out in an already constructed building. In this case, the solution is applied using a brush or roller. This surface coating lasts approximately 2-8 years. Deep impregnation in such cases is only possible with the help of special devices or under pressure.
It is for this reason that it is optimal to process parts before assembling the structure - by immersion.
Regardless of the chosen method the most important rules When processing rafters, care must be taken to handle the impregnating layer and maintain its integrity. Damage may be caused by being dropped from a significant height or coming into contact with sharp-edged instruments.
Universal remedies: to use or not to use?
Repeated processing and coating is a rather labor-intensive process. Of course, I would like to limit myself to a one-time treatment of the rafters with a universal solution, followed by drying and installation in place.
Similar impregnations are already commercially available. They contain not only an antiseptic component that protects against fungus and mold, but also an antipyretic in the form of a solution of certain salts, which protects the material from fire.
Despite its superficial appeal, this “universal” method has one significant drawback: when using it, it is not possible to determine whether the material has been properly impregnated or not. Once the layer has dried, processing can no longer be continued, since a protective film has already formed on the wood.
In addition, the duration of exposure to the additives included in the product can vary significantly. For example, the effect of antiseptics lasts 2 years, and antipyretics – 10 years. In this case, the wood will be protected from fire, but fungus will appear in it or rot will begin. In this case, re-impregnation with the solution is impossible, since the protective film is still preserved. Conclusion: it is better to abandon the dubious versatility and choose a method that provides high-quality processing.
CONCLUSIONS:
- Treatment of rafters is necessary to protect them from rotting and exposure to flame.
- With high humidity, the main danger is possible rotting of wooden elements. In hot climates, the first thing to think about is protecting the structure from fire.
- Fire retardants are produced in the form of impregnations, coatings, varnishes, and paints.
- Antiseptics are purely protective and can have a decorative effect.
- Simultaneous treatment of rafters with several drugs is unsafe, since they can react with each other.
- Surface impregnation of wood is carried out by immersion in a protective composition or by spraying with a spray bottle and applying with a roller or brush.
- The higher the moisture content of the material, the better it is impregnated.
- When using impregnation, you must follow the manufacturer's recommendations regarding the amount of solution and method of its application.
- The universal products offered to consumers cannot provide adequate protection of rafter elements.
Find out how to prepare wood impregnation with your own hands from the video.
Such a disadvantage of wood as flammability and susceptibility to bio-impacts, at the same time, indicates the naturalness and environmental safety of the material.
Molds often appear on damp lumber that is not stored correctly: close to each other, without the possibility of ventilation.
Serious damage can be caused by insects: grinder beetles, bark beetles, larvae, wood-boring butterflies and others. As a rule, various fungi appear in deep wormholes - insect passages.
Wood various breeds resists external biological influences in different ways.
In accordance with this indicator, there is a division into four resistance classes. The most resistant species are pine, ash, oak and larch.
It is undesirable to use even slightly damaged elements - boards, beams - in such an important task as constructing a roof. However, as a last resort, they can be treated with a disinfectant. Boards with rot are completely unsuitable for use.
- deeply penetrating – impregnation;
- surface treatment - coating.
Antiseptics are divided into:
- water soluble. The powdered substance for use is diluted in water. For example, the Senezh Trans antiseptic is diluted in water in the ratio of 1 liter of dry powder to 24 liters of water;
- oily. Substances based on organic solvents - for example, creosote and anthracite oil. Not suitable for home use due to toxicity.
In order to reduce the financial costs of construction, self-made impregnations are used, for example, based on beer malt.
The rafters are also treated with lime or lime with copper sulfate. However, we must remember that these are potent and sometimes toxic substances.
And it is unknown how they will behave when interacting with fire retardant compounds and whether they will perform the functions assigned to them.
With the current variety of special impregnating compositions, it is better to give preference to special water-soluble products - they are non-toxic and also provide longer-lasting protection. Their cost is not comparable with the possible damage.
What is the consumption of the chemical
Consumption depends on many factors, including the species, quality of wood and cross-section of the timber, and weather conditions.
Average indicators: to cover the boards with one layer of water-based antiseptic, you will need 250-500 g/sq.m. m.
Fire retardants
Reducing flammability is a very important and critical stage in roof construction.
In a house with a wooden rafter system without treatment with fire retardants, in the event of a fire, a situation may arise that the fireman will no longer have anything to save.
To reduce flammability, wood is treated with chemicals - fire retardants, which can be salt or non-salt.
When heated, these substances melt, covering the rafters and sheathing boards with a film.
Without access to oxygen, combustion cannot be supported.
Another option is when oxygen is pushed away from the beam due to the release of non-flammable gases by fire retardants when heated.
Fire retardant compounds are applied:
- coating the wood with a brush or roller;
- spraying;
- by immersion in a solution;
- under pressure - in autoclaves. This way ensures the fastest and deepest impregnation.
To protect wood, in addition to impregnation with fire retardants, they use
special varnishes and paints.
The effectiveness of fire protection is determined in laboratory conditions. 
There are two groups:
- first;
- second.
Composition consumption for efficiency group 1 when using, for example, “Neomid 450-1”: 250 g per square meter.
The most important
The fibers can be impregnated with only one of the compounds - an antiseptic or a fire retardant, the second is used for coating, so you need to decide what is more important in a particular case: to prevent the appearance of rot or to protect the rafters from fire.
Combined impregnation
To save developers from the painful choice, combined impregnations were created - all of them are water-soluble.
In addition to fire retardants and antiseptics, the composition of fire bioprotection may include substances that tint the wood - giving it a tint.
Of course, such a product is very convenient to use, but some experts criticize its versatility: after all, the service life of fire retardants is shorter than that of antiseptics.
But it is not possible to check how well the composition protects the rafter system.
An example of a product that simultaneously provides protection from insects, rot and from fire and flame spread is Senezh Ognebio.
The consumption of such a product for wood ranges from 300-600 g/sq.m. m.
Selection of powdered protective substances and liquid formulations very wide. The Russian market mainly presents products from domestic manufacturers.
Work order
The wooden or board is cleaned of dust and construction debris, greasy stains, the surface should not be painted or treated with drying oil.
The wood must be coated evenly with the protective compound. It is recommended to apply at least two protective layers to the rafters and sheathing.
The main disadvantage of any treatment is that its effectiveness decreases over time, so it is necessary to periodically repeat the application of the protective composition.
