How to treat rafters and sheathing? What is the best way to protect against rotting and fire? Fire protection of wooden roof elements. Is it necessary to treat wood for the roof?

During the construction of the roof of a house, a very pressing question is how to treat the rafters so that they do not change for a long time under the influence of moisture, temperature changes and are protected from fire. The modern chemical industry has various means for processing wooden materials. Their choice depends on the specific conditions of use and the final requirements for the structures.

To prevent the rafters from becoming unusable, they need to be treated by special means.

What are the dangers to wooden roof structures?

The main enemies of wood are high humidity, fungal spores and insect larvae. Acting alone or in various combinations, these factors quickly lead to damage to the material of rafters, beams and sheathing. The negative effect is enhanced by physical activity from roofing material and snow cover, as a result of which the rafters first bend and then completely break in weakened zones.

In order to properly deal with factors dangerous to wood, it is important to recognize them in time. For this purpose, roof structures and rafter systems should be periodically inspected for destructive changes. It is quite difficult to identify them, especially at the initial stage, but still possible. Let's look at typical signs of rot, mold and pests:

After several seasons of decay, the wood becomes brittle, loose and loses some of its weight.

1. Rotting begins with a change in the color of individual fragments of wood: while maintaining the overall structure and strength, the material in some places turns reddish-brown and violet-gray tones. With the subsequent development of the process, brown color begins to predominate, white films and cracks appear. After a few seasons, the wood becomes brittle, loose and loses a significant part of its weight. It all ends with rafter system you can literally pierce it with your finger or tear off a piece from it.
2. Mold acts in combination with rot, intensifying it. Due to the fact that fungi need moisture to function, they collect and accumulate it between cellulose fibers. This leads to accelerated destruction of wood, the appearance of an unpleasant mushroom smell, and increased humidity in the attic. Mold develops more easily in deciduous wood, since coniferous trees have natural protection - resin, which at least slightly slows down the growth of fungi. The first sign of mold is a black coating that spreads along the cellulose fibers. During the ripening period, the spores may acquire grayish, even white, shades. In particularly advanced cases, the body of the fungus itself appears and begins to grow on the walls.
3. Insect pests are a major threat to any wooden structure. By a happy coincidence, such powerful wood pests as termites have chosen warmer tropical and subtropical regions for themselves. However, even without them, there are more than a dozen species of insects that are not averse to feasting on your home or bathhouse. The most famous among them are the wood-boring beetle, bark beetle, and shashel. Adults can also feed on cellulose, but the larvae do most of the damage. Their presence can be recognized not only by characteristic holes in the beams, but also by specific sounds in the house: the larvae make a clicking noise that is easy to hear at night.

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How to treat rafters against rotting?

Rafters should be treated with an antiseptic.

The fight against decay processes begins at the stage of selecting and purchasing material. Before purchasing, be sure to inspect all beams in detail, determine their approximate moisture content and pay attention to the absence of uneven, unnatural coloring. If necessary, additional drying of the material should be done before starting work.

Majority building materials, presented on the market, are necessarily treated with agents against rot, mold and pests. The seller must have an appropriate certificate on hand, which shows the depth of impregnation and the safety of the substances used. However, when working with wood, you will be sawing it and treating the surface, thereby removing the protective layer, so impregnation of such areas will have to be done again.

All protective equipment is divided into three types:

• paints;
• varnishes;
• antiseptics.

In most cases, antiseptics are used to treat roof structures, since they have a significant penetration depth and do not change appearance wood and, unlike varnishes and paints, do not begin to peel off over time. Antiseptics are applied either by immersing the material in their solution or by spraying. Apply the first method in conditions self-construction almost impossible, since it requires special expensive equipment. Spraying is a fairly affordable method; a regular sprayer used for garden plants is suitable for its implementation.

It is best to do the treatment after the construction of the main structures, because working with materials soaked in chemicals is quite unsafe.

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How to protect against mold?

Copper sulfate can be used to treat wood.

The development of mold often occurs unnoticed by humans, and its external manifestations on the walls only mean that the entire mass of wood has already been infected with the fungus. Contrary to popular belief, regular surface cleaning will not lead to a noticeable improvement in the situation. The only way to combat mold is to limit its access to food: air and atmospheric moisture.

Processing can be carried out in two ways: using either modern chemicals, or traditional methods. The second option is less reliable, but is quite often used in everyday life. It involves treating a pre-cleaned surface with hydrogen peroxide, chlorine bleach, soda, vinegar essence, ammonia, copper sulfate, borax, drying oil and other means. Judging by the fact that some specific means " traditional methods“do not offer, such a fight is unlikely to be effective and can only remove the external manifestations of the fungus.

Factory-made chemical impregnations are able to penetrate deeply into the wood, killing spores and mycelium. They are safe for humans, are relatively inexpensive and can be easily applied to the surface of the rafters using a spray bottle.

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. Thus, excess moisture can become a favorable factor for the development 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 an almost impossible undertaking, 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 assembling them in roof structure just planned, don’t rush, it’s better to do 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 are slightly larger than the overall dimensions of the rafters; on the inside it is covered with plastic film, which is adjusted 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) that interact with antiseptic additives and resist the formation 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 a protective film has already appeared on the surface.

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?

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 by high air humidity, then antiseptics that need to be soaked into the wood will be most relevant. The sequence of processing is important - the composition applied first works much more efficiently than subsequent layers.

Types and characteristics of antiseptics - the best way to treat them

Most antiseptics for rafter systems can increase the decorative properties of the structure 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. Main disadvantage– treating rafters with Pinotex antiseptic is not possible if they are already damaged.

A good alternative to foreign products is the domestic antiseptic Drevotex, which provides reliable protection 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 it is necessary 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:

1. Impregnations. These substances are salt solutions that are applied to the wood by immersion or manual processing.
2. Lubricants. This category of fire retardants is distinguished by its paste form.
3. Lucky. Varnishes are most often used as a decorative coating, so their use for treating rafters would be inappropriate.
4. 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;
• Protective composition Neomid, manufactured at water based, can be used immediately after purchase, without additional preparation.

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.

How to treat rafters and sheathing: treating the rafter system with a roofing antiseptic, impregnation, whether it needs to be treated

The procedure for processing the rafter system

Treating rafters with special compounds that prevent biological destruction and reduce the risk of fire allows you to extend the service life of the rafter system.

Changing the properties of wood

For construction wooden structures, in particular, for the rafter system of a house, wood of various species can be used, each of which has its own properties and degree of resistance to external influences. When choosing lumber, you need to pay attention to such characteristics as:

• wood moisture level;
• grade (presence of cracks, knots, etc.);
• moisture resistance;
• wood resistance to rot and pests.

To increase the resistance of the material to biological destruction, it is necessary to treat beams, rafters and other elements of the roof frame with special means. At the same time, we must not forget about fire retardants, which give wood an unusual resistance to fire.

At the pre-construction stage, it is important to decide on the means that will be used for processing. Today, the construction market offers a wide selection of antiseptics, fire retardants and universal fire-bioprotective agents that need to be used to treat elements of the rafter system.

Selection of means and order of processing of the rafter system

Biological destruction refers to wood rotting (infestation by fungi and microorganisms) and the impact of pests on wood fibers (primarily wood-boring beetles). To protect the rafters from biological destruction, antiseptic treatment is necessary. If the wood is already damaged, it must be impregnated with a disinfectant. Otherwise, in a humid climate, the destruction of the rafter system will occur in a short time. The danger of fire always remains, and fire-retardant treatment of wooden elements is relevant when constructing a rafter system in regions with any climate.

When using an antiseptic and fire retardant, you need to choose the right order of application: one composition (the main one) should be an impregnation that penetrates deep into the wood, the second should be a coating that creates a top protective layer.

If the area is not arid, it is recommended that you first take care of protecting the rafters from rotting. High-quality impregnation with an antiseptic will create a reliable barrier to fungus and pests. Coating with a fire retardant will help reduce the risk of fire.

In regions with arid climates, you should worry about fire protection and impregnate beams and rafters with fire retardants. To prevent wood from being damaged by rot or bugs, a bioprotective composition is applied to the surface of the wooden elements.

You can antisepticize the rafter system using various means. There are special compositions that destroy the larvae of pests - wood-boring beetles, drugs are offered that successfully combat common black rot, etc. When buying an antiseptic, you need to make the right choice based on the specifics of specific conditions. It is impossible to mix different preparations, as their combined effect on wood fibers can be destructive.

Rafter processing

To ensure reliable protection of the wooden elements of the rafter system, it is not recommended to process the finished roof frame. In this case, the most problematic areas remain inaccessible: fastening points. Moisture can penetrate the joints and cause rotting of untreated wood. To eliminate this, you need to carefully process the rafters, beams and other parts of the structure before installing the rafter system.

It should be taken into account that impregnation with an antiseptic ready-made structures using a brush or spray is less effective than the dipping method, which can be applied to individual roof framing members.

Full treatment of rafters involves deep impregnation of the wood with an antiseptic. The maximum effect can only be achieved under production conditions, since for better penetration of the protective composition, the wood should be heated and the solution should be supplied under pressure. Processing directly on the construction site is of lower quality, but with a careful approach it also gives a good result.

To use the immersion method, it is necessary to build a container of the required dimensions, taking into account the length of the rafters and the width of the beam. For this purpose, a ditch of a certain depth is dug, or a long box is knocked together from boards. In both cases, the surface of the improvised container is lined with plastic film, which is secured to the sides. Next, pour a diluted antiseptic into the container (the concentration of the composition is indicated by the manufacturer) and alternately immerse the beams, rafters and other wooden parts. Each structural element must be kept in the solution for 2-3 minutes.

Rafters and other parts of the roof frame should be dried for about a day, placing them in such a way that all sides are ventilated.

The ends of the rafters, grooves and cuts need to be treated especially carefully, since these places near the rafters are the most vulnerable. To do this, the rafters, already impregnated by immersion, are additionally treated with an antiseptic in problem areas using a paint brush.

If you have to process beams, rafters and other structural elements by applying surface impregnation using a roller, sprayer or brush, you need to carry out the work at least twice. Before the first and second treatments against pests and rot, the wooden parts must be completely dry..

Processing of rafters should be carried out in warm time of the year. There is no point in treating frozen and damp wood - the fibers will not absorb the antiseptic. Antiseptic treatment should be carried out in compliance with safety precautions - protective equipment must be used. The compositions used can cause a chemical burn if they come into contact with unprotected skin.

After the antiseptic has penetrated into the wood fibers and the part has completely dried, it must be treated with a fire retardant. The coating composition is applied to the surface of the rafters with a paint brush or a soft paint brush, or you can use a small roller. The product is diluted in the concentration specified by the manufacturer.

Universal means

Using an antiseptic and a fire retardant separately, the rafters must be treated in several stages. The use of a universal fire-bioprotective agent significantly simplifies and speeds up the work. Universal impregnation for rafters is applied in one go, but this presents certain difficulties: after treating the rafters, a protective film is formed on the surface of the elements, which prevents the penetration of the drug when applied again. Thus, if the impregnation against pests and fire was carried out insufficiently, the situation cannot be corrected. It is worth noting that the composition of a universal product may include a fire retardant and an antiseptic with a different duration of action.

How to treat the rafter system, treatment and impregnation for rafters

Rafter processing technology and types of antiseptics

The choice of rafter system for the roof is extremely important. The most common material for it now is wood, from which they are made. various boards, sheathing, rafters and other elements of the roof structure. Wooden rafters have been used in construction since ancient times. They have many excellent performance qualities. Before assembling the roof frame, it is necessary to take care of the processing of the rafters and carry it out correctly so that they serve reliably and for a long time. How to treat rafters is a good question, and it’s worth thoroughly understanding it.

Need for impregnation

Many people know that wood rots over time. Microorganisms that appear in it destroy the fibers, which is why this material loses its beneficial features. The strength of the rafters is also determined by the type of wood. Different tree species differ in their degree of flammability and susceptibility to rot. When constructing a roofing structure, in most cases, coniferous types of wood are used, but they have a big drawback - they easily ignite due to their high resin content.

In order to really assess the negative factors that can negatively affect the roofing structure, it is necessary to analyze the characteristics of each specific region. In high climate humidity, the main danger will be the likelihood of accelerated rotting of wood. In case of increased temperature regime First of all, you need to think about protecting the product from fire.

For processing rafters and sheathing there are now many various means. Applying special compounds to the rafter system helps protect it from both fungus and fire. This composition must be chosen very carefully, taking into account the characteristics of the material and the climatic situation in the region.

Types of impregnation of rafters

Impregnations can be antipyretic and antiseptic. You can buy wood already processed, but most often it is still sawn at the construction site, so new cuts need impregnation.

Antipyretics may account for some of the weight loss in treated wood. Despite the quality characteristics of the rafters, periodic checking of their condition is required. In case of non-compliance with the standards, work must be carried out to restore and replace low-quality parts.

Fire retardant materials are divided into the following types:

• Impregnations are solutions of salts that are applied in several ways: under pressure, by immersion and by ordinary hand;
• Coatings are mixtures of pasty consistency;
• Varnishes are intended for those cases when it is necessary to preserve the original appearance of wood;
• Paints – form an opaque thin film when applied to a surface.

Fire retardant impregnations are intended for both closed and open areas.

Antiseptics are classified a little differently. They are used either for protection or to create a decorative effect. Protective antiseptics are washed out in different ways, dissolving in water, light solvents, oil, and petroleum products. During construction, water-soluble antiseptics are mainly used. They have certain advantages:

• Dries quite quickly;
• Form a durable film on wood material;
• They do not interfere with the ventilation properties of wood, i.e. the tree still “breathes,” as people say.

The basis of antibacterial impregnations, which serve to create a decorative effect, are alkyd resins. During appropriate processing, even ordinary pine can easily turn into a tree of almost any valuable species. This impregnation contains a solvent, which provides excellent adhesion and penetration to a sufficient depth.

In regions where the climate is humid, wood is more susceptible to fungus. Rafters are treated to protect against it, taking into account their initial condition. Most often, aqueous solutions of certain agents are used. If the tree is already affected by fungus, the mandatory use of specialized disinfectant impregnations is required.

To protect wood from beetle larvae, special compounds are used. It is worth considering that it is not safe to treat rafters with several products at the same time, since they can easily react with each other. It is not recommended to use drugs such as copper sulfate or potassium bichromate. They can change the initial color of the tree, and are also quite toxic.

Today in hardware stores you can find many different compositions that allow you to perfectly protect wood from all sorts of threats. Such products as Rogneda, Drevotex, Senezh, Olympus have already proven themselves well. Some of the above compounds are produced in series intended for various purposes: against fungus, against mold development; from a beetle; for processing the ends of houses and so on.

Important! First, the entire structure must be saturated with the main composition, then it is coated with an additional one.

Wood processing methods

Impregnation (surface impregnation) of wood is carried out in two main ways: immersion in a prepared protective composition and application using a spray roller or brush. In the first option, wooden elements are immersed in a specialized container with a protective agent. Treatment is carried out with a cold solution at ambient temperature or a hot solution - up to 60 degrees. Sometimes a contrast impregnation method is used. In this case, the wood is first immersed in a hot solution, and then immediately into cold impregnation. This method of unexpected cooling improves the capillary absorption of the material; they manage to saturate the wood to a twenty percent moisture level.

The method of applying impregnation by spraying, spraying, painting differs from immersion in its simplicity and low cost. The advantage of this option is the ability to process ready-made structures. But in terms of efficiency, it is clearly inferior to the first method due to the insufficient depth of penetration of impregnation into the thickness of the wood, as well as the impossibility of processing hidden parts of the structure without disassembling it.

Important! When using impregnation, you must follow all the manufacturer’s recommendations regarding the amount of solution and the method of its application.

All manufacturers of impregnation products are required to accurately indicate in the instructions for use the duration and method of wood treatment. The universal impregnation products offered to consumers in many stores in fact cannot provide adequate protection for rafter elements, so you should approach the choice of each product for each layer wisely and it is better not to skimp on it.

Treatment of rafters with an antiseptic and how to treat the sheathing

How to treat rafters and sheathing? What is the best way to protect against rotting and fire?

The main final part of the construction of a house, bathhouse and other buildings is the installation of the sheathing and rafter system. They are made from wood, regardless of the main material used to build the walls. Wooden material is durable; a rafter system made from it can withstand the loads imposed by the roof. Before assembling the roof frame, you need to take care of the protective treatment of the wood.

Why do you need to treat rafters?

Over time, the strength characteristics of the sheathing and rafters may weaken due to the influence of biological agents on them. After all, wood is attractive to insects, fungi, mold, moss, etc. Under their influence wood material begins to deteriorate, often resulting in an irreversible process of rotting. All this can lead to the destruction of the roof. To protect the rafter system and sheathing from the unwanted effects of pests, it is necessary to use special protective compounds.

Another dangerous enemy of wood is fire. Because of high temperatures the wood ignites and the fire spreads across the entire surface instantly. This can lead to a fire not only of the roof, but of the entire house.

Products for processing rafters and sheathing

It is imperative to purchase antiseptic compounds. Their use will help protect the rafter system from biological pests, insects and rot.

You can prevent ignition and further spread of fire by treating the wood of the rafters with fire retardants. Their compositions contain active flame retardant substances, which are responsible for the resistance of the wooden material to high temperatures.

There are also complex bioprotective products for treating wooden rafters. They protect the treated wood from the effects of biological pests and from fire.

Expert opinions

It is necessary to provide additional protection to the sheathing and rafter system. After all, wood, as you know, is susceptible to rotting. Microorganisms formed in the wood structure rapidly begin to destroy the fibers, which leads to a deterioration in the strength properties of the entire structure. Antiseptics will help prevent the formation of biological pests for decades. But it is advisable to use powerful formulations that are indelible. It is also recommended to treat the rafter system with deep-penetrating antiseptics; their compositions penetrate deep into the wood structure of the rafters and provide it with longer-term biological protection.

For the construction of the rafter system, mainly coniferous species are used, which, due to the presence of their resin structure, ignite instantly. Therefore, it is necessary to use fire retardants, especially if the building is located in a hot climate. These compounds, after being applied to a wooden material, provide it with a second or first degree of fire resistance, it all depends on the product itself. It is better to purchase fire retardant impregnation with the most highest level resistance to fire.

Fire challenge protective compounds is to prevent the fire from spreading to the wood. This is accomplished by swelling of the film of the composition under the influence of high temperatures, and preventing the penetration of oxygen into the wooden material. Therefore, the fire cannot be maintained and gradually begins to die out.

Antiseptic and fire retardant products are available in a wide range. You can choose from domestic and foreign compositions. But as practice has shown, Russian goods do not differ in quality, and in some ways they are even superior to foreign ones. They also have an advantage regarding the cost of funds. Therefore, we recommend that you take a closer look at our manufacturers. Good reviews, the companies Neomid and Prosept are popular. Their products will help to reliably protect the rafter system and sheathing from rotting and fire.

Repeated treatment of the rafter system and sheathing with various protective compounds is inaccessible or inconvenient for many builders. After all, it takes a lot of time, effort, including Money. Therefore, to save and reduce operating time, you can use complex fire-bioprotective compounds. By treating wooden material with only one product, you can protect it from fire and from mold, rot, moisture, and insects.

But if complex products are used, their protection period must be taken into account. The composition is effective against the formation of biological agents for about 5 years, and fire protection will be effective for 10 years.

It is recommended to treat wooden structures only in the warm season, preferably in the summer. There is no point in applying protective compounds to frozen or damp wood, its fibers will not absorb the protective agent.

How to treat rafters and sheathing? What is the best way to protect against rotting and fire?

The rafter system, being an important component of the structure of the roof and the entire house, is often made from lumber. Wood, as you know, is susceptible to biological decomposition, mold, mildew, and insects. Therefore, in order to protect the construction material, it is necessary to treat the rafter system with special compounds. And how to treat rafters is described in detail in this review.

Basic properties of protective compounds

Protective agents (antiseptics) used to treat rafters, sheathing and other wooden roof elements have the following important properties:

• They penetrate deeply into the wood.
• They are applied easily to the surface and dry quickly.
• Do not interfere with normal ventilation of the processed material.
• Safe for humans and animals, non-volatile, do not irritate the skin.
• They do not lose their properties upon contact with water.
• They create a reliable protective barrier against biological destruction and fire of wood.

Most protective agents can also improve the decorative properties of wooden elements. This is achieved due to the alkyd resin contained in the composition, which changes the shade of the wood.

A unified characterization of properties requires a more detailed consideration in the context of a specific composition. Therefore, at the preparatory stage it is necessary to correctly prioritize and decide on the main processing task. For operation in humid climates, the following processing sequence will be optimal:

• The first layer is a deeply penetrating antiseptic.
• The next step is the application of fire retardants, which make the wood resistant to fire.

It is important to maintain consistency when processing rafters. The enhancement of specific properties - biological resistance or fire protection - depends on which composition is applied first.

Types of wood preservatives

Wood antiseptic is an impregnating composition that has special properties aimed at destroying mold, mildew and insects that destroy the integrity of lumber.

Types of wood antiseptics depending on the purpose:

• Preventive - used for initial stages, immediately after purchasing lumber.
• Medicinal - designed to eliminate existing problems when the wood has already rotted or been damaged by insects. Sometimes it is appropriate to use such compositions as a preventive treatment, when it is assumed that the structure will be operated in unfavorable conditions (high humidity).

Types of antiseptics depending on the composition:

• Water-soluble ones are used for preventive purposes to treat surfaces that will not have direct contact with water in the future.
• Oil paints are used in cases where it is necessary to protect wood from moisture. The disadvantage of such means is flammability, bad smell and the ability to change the color of the material.
• Antiseptics based on organic solvents are used when treating wood to give it hydrophobic (water-repellent) and adhesive (improving adhesion) properties. Can be used for both outdoor and interior work. After drying, they form a protective film.
• Combined - combine several properties (protect against insects, mold, mildew, and at the same time have fire-retardant properties).
• Winter antiseptics are used at temperatures as low as -15°C.

When choosing antiseptics for treating the rafter system, pay special attention to the instructions. Certain products can cause metal corrosion, react with adhesives and sealants, and be toxic.

Let's look at examples of antiseptics from various manufacturers:

	Antiseptic "Senezh Ecobio" is intended to protect wood from rot, mold, blue stain and insects (woodworms) indoors and outdoors (under a canopy) under conditions of hygroscopic and condensation moisture without contact with the ground, exposure to precipitation, soil moisture alone or in as a bioprotective primer for paints and varnishes.
	"Pinotex Impra" (Pinotex Impra) is an antiseptic (impregnation) for treating wood with deep penetration, water-based with a high content of biocides. Protects hidden wooden structures from mold, blue stains and rot. Has a green indicator to ensure uniform application. It has excellent impregnating properties and prevents moisture from penetrating into wood. Easy to apply, without splashing or drips. Does not have a pungent odor.
	"Drevotex" is a remedy against the possible occurrence of rot, mold and insects inside wood. Designed for processing wooden structures that are located indoors or under a canopy. Suitable for use in moderate weather conditions. It practically does not wash out when moisture gets on it and does not interfere with the passage of air to the wood.

It is worth noting that there were particular examples of antiseptic compositions considered. If you study the entire range in more detail, you can highlight a huge variety of products. So, for example, in the Senezh line of antiseptics there are the following positions:

• “Senezh aquadecor” is a tinted antiseptic on an alkyd-acrylate base with a UV filter and wax for long-term protection and finishing of wood.
• "Senezh ecobio" - economical colorless antisepticfor indoors and wooden structures under a canopy.
• "Senezh Ultra" is an economical, hard-to-clean antiseptic for wood for external and internal use.
• "Senezh" is a preservative, difficult-to-wash-out antiseptic for critical structures in harsh operating conditions.
• "Senezh Bio" is a preservative, difficult-to-wash-out antiseptic for residential buildings in harsh operating conditions.
• "Senezh impra" is a concentrated, non-washable antiseptic without chromium for deep impregnation of wood.

Fire retardants for rafter systems

Fire retardants are special compounds that increase wood's resistance to fire and reduce flammability.

In most cases, fire retardants are applied as a second layer after antiseptics. However, if there is a high risk of fire in the rafter system, then they must be used as the main impregnation.

Depending on the specific purpose, fire retardants are divided into:

• Impregnations - salt solutions.
• Coating agents are in paste form.
• Varnishes are used as a decorative coating.
• Paints create a thin film on the surface of the wood, which provides protection from fire.

When using fire retardant as the main means of treating rafters, the best option there will be impregnation. Coating compounds are suitable if they are applied over an antiseptic.

Let's look at examples of compositions based on fire retardants from various manufacturers:

	The product "Senezh Ognebio" is intended for comprehensive protection of wood from fire, flame spread, rot, mold, blue stains and insects (woodworms) indoors and outdoors (under a canopy) under conditions of hygroscopic and condensation moisture without contact with the ground, exposure to precipitation , soil moisture.
	"Pirilax-Classic" (Pirilax Classic) is a fire- and bioprotective impregnating composition for wood and wood-based materials. For external and internal works. The product protects wood from fire and stops the spread of flames. Destroys mold and wood-staining fungi, algae and prevents their reappearance. Protects against woodworm beetles. Increases the service life of wooden buildings. Reduces wood cracking and preserves the surface. Compatible with most paints and varnishes.
	"Neomid 450-1" is a highly effective fire protection and antiseptic agent for wood for external and internal work under conditions that prevent the composition from being washed out from the treated surface. Converts wood into a low-flammability and low-combustibility material, providing Group I (first) fire-retardant efficiency, protects against rotting and mold. Designed for comprehensive protection against fire and biological damage to wooden structures and products (walls, beams, building systems, load-bearing beams, ceilings, joists, window and door blocks).

As you can see, most fire retardants for rafters and other structures, containing fire retardants, also perform antiseptic functions. In fact, these are universal products with a pronounced fire-resistant effect.

Methods for applying protective compounds to rafters and sheathing

Same. Wood protection measures can be carried out in several ways:

• Immersion method. In this case, the rafters are treated by completely immersing them in an antiseptic. To work, you will need a large container (a bathtub or a regular pit covered with plastic film) filled with a protective compound.
• Surface application - spraying, spraying or painting. This technology is less effective. Therefore, for high-quality treatment, the compositions must be applied to the rafters and sheathing in several layers with an interval for drying.

In conclusion, it is worth noting that soft wood absorbs more antiseptic than hard wood, and coniferous wood, in addition, can release resin, which negatively affects the protective properties after treatment. Also, as noted above, it is important to decide how to process the rafters, and in what order to do it. Thus, the first applied product affects the protective characteristics more than the subsequent layer of another product.

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 of different species 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 retardants 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 sustained.

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.

The choice of powder protective substances and liquid formulations is 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.