How to insulate ventilation in a cold attic: rules and procedures for thermal insulation of pipes

Competent ventilation system design involves insulation of air ducts. Otherwise, they are doomed to constantly become covered with condensation, causing irreparable harm. Based on this, the question of how to insulate ventilation in a cold attic is very important, because it is there that there are all the prerequisites for the accumulation of moisture inside the pipes.

We will tell you everything about the purpose and specifics of the thermal insulation device for the ventilation duct system. We will analyze all the options for warming air ducts using materials that are different in structure and purpose. Home craftsmen who want to carry out the work on their own will find a detailed guide here.

Arguments in favor of ventilation insulation

The process of accumulation of condensate inside an uninsulated ventilation pipe is inevitable. This is a consequence of the collision of warm and cold air currents. To a large extent, the fallout of condensation is facilitated by failures in the system and deviations from the rules for the operation of premises.

Both the moisture deposited on the structures and the condensate that has fallen on the walls of the air ducts flow down the pipes. Through any leaks at the joints, they will fall on ceilings and walls. Because of them, the insulation of the floor gets wet, as a result of which its insulating qualities are reduced at least by half.

At a negative temperature, frost appears, and the inner diameter of the pipe will decrease. Not only the material is destroyed, but also good conditions are created for the life of molds. Residents of the house are threatened with frequent respiratory diseases and allergic reactions.

Ventilation in an unheated attic especially needs insulation. Here, the difference between the temperature of the air inside the system and the walls of the pipes is significant.

Only the fabric air distribution system does not require additional insulation. Condensation does not form on the vapor-permeable surface of textile pipes, and since the channels are dry, microorganisms do not settle in them.

Air saturation with steam is directly proportional to temperature. The higher it is, the more steam is in the air masses. Even the smallest change in temperature reduces the property of air to retain water in the form of steam. For this reason, condensation accumulates at the outlet of the ventilation duct when the air is cooled.

Where to insulate the ventilation pipe?

Mandatory insulation is necessary in places where the temperature difference occurs. In areas where warm and cold air comes into contact, condensation appears most abundantly. The dew point is here. When designing the insulation of the exhaust ducts, the position of this point is calculated first of all.

The challenge is to move it as close to the outlet as possible ventilation pipe. Ideal when the mixing zone of cold and warm air flows is taken out of the house.

Since this is rare, on the ventilation pipe that crosses the cold attic and then goes to the roof, the zone of passage through the ceiling of the upper floor or attic is subject to insulation. The pipe itself is insulated along its entire length until the very exit to the roof.

In the case of supply ventilation, the amount of condensate falling out on the outer walls of the ventilation duct is directly proportional to its length. Influences this phenomenon and the feature of installation. In large rooms, in addition to pipes, valves are also insulated.

The insulated damper looks like an adjustable louver. The latter restrict the passage and somewhat increase the temperature of the air supplied from the outside, because the design includes tubular heaters.

The speed of the air supplied through the valve is controlled by means of levers or an electric drive system. Heating the valve blades by heating elements is necessary to prevent their icing. This changes the temperature of the supply air masses insignificantly.

Thermal insulation materials for pipes

After determining the dew point and carrying out the necessary calculations, the question remains, how can the ventilation in the attic be insulated, by what criteria to evaluate the material. High-quality thermal insulation is possible subject to the correct choice of insulation, its thickness, taking into account the humidity of the air inside and outside, the temperature difference.

Key selection criteria

There are three main criteria for choosing an insulating material:

• thermal conductivity level;
• fire safety level;
• material price.

Consider the most popular thermal insulation materials, their inherent advantages and disadvantages. The most popular are mineral fiber based insulation. This group combines cotton wool from slag, fiberglass, basalt threads thinly stretched during the melting period.

Basalt, it is also stone, wool is distinguished by both characteristics and cost. Slag is harmful to health, and it is better not to use it.

Glass wool for thermal insulation of ventilation

Glass wool is in the greatest demand among materials based on mineral fibers.

Thermal insulation coefficient - from 0.03 to 0.052 W / m2. The heat insulator has long fibers, intertwined in such a way that a shell is formed, resembling a cocoon, which holds air in it.

The positive technical characteristics of the material are as follows:

1. Fiber thickness is 3-15 micrometers, length is from 15 to 50 mm.
2. Good absorption of noise vibrations and acoustic interference due to the even distribution of fibers. This indicator for insulated structures fluctuates in the range of 35-40 dB.
3. Fire resistance ranging from NG to G1. Although binder resins are present in the material, it is not self-igniting. Without changes in the structure of glass wool, it can withstand temperatures up to 250⁰.
4. Resistance to mechanical stress. Early analogues of this insulation did not have good resistance to mechanical stress. Modern samples have sufficient strength, good elasticity.
5. The vapor permeability index of glass wool is 0.6 mh / Pa, which is almost 2 times higher than that of basalt.
6. The daily sorption moisture is less than 1.7%.
7. The material has good biological resistance. Rodents do not settle in it, mold fungi do not multiply.
8. Without loss of quality characteristics, glass wool can be compressed 6 times. After straightening, the elastic fibers return to their original position.
9. The average density is 11-25 kg / mᶾ, but the indicator may differ from manufacturer to manufacturer.

If you do not allow it to get wet, high-quality insulation does not shrink during prolonged use.

The negative is the increased fragility of the fibers. It is permissible to work with glass wool only with the use of protective equipment. To prevent the finest sharp fragments of fibers from getting into the surrounding space, reliable insulation of the insulating layer is necessary. Protection is also necessary in order to neutralize the destructive effect of sunlight on glass wool.

In addition, glass wool has a relatively short service life - about 10 years. When choosing insulation for ventilation pipes in a cold attic, it is imperative to be interested in whether the product has a conclusion on its compliance with hygienic and sanitary-epidemiological requirements.

Round ventilation sleeves are insulated with rolled mineral wool. Ventilation pipes with a square section - material in the form of plates. The ventilation duct is wrapped first and fixed with metal wire or synthetic tape. The second ones are glued.

Features of the use of basalt wool

This material is an advanced mineral insulation. It consists of molten basalt fibers. It is produced in the form of slabs and mats. For round ventilation ducts, ready-to-use heaters are produced in the form of cylinders covered with insulation - foil. There are products without an insulating layer.

The thermal insulation coefficient of the material is 0.034-0.038 W / m2. Cheap brands that contain formaldehyde resins can be hazardous to human health. In a more expensive insulation, completely harmless biopolymers are used as binders. The price of basalt wool is higher in comparison with the glass wool analogue.

Polyethylene foam for ventilation insulation

Applying foamed polyethylene to round and square air ducts within the attic is a simple and inexpensive option for insulation.

There are several varieties of this material:

1. Normal. This category includes penolon (cross-linked polyethylene foam), isolon, and others. Its use is extremely simple - they wrap the air duct with pieces of material and fix it with tape.
2. Foiled. This insulation is covered on one side with a layer of foil designed to reflect heat and repel moisture. It goes on sale under different names: tepofol type A and B, penofol, mosfol, faralon, ultraflex. This insulator is connected with special glue or aluminum tape.

Insulation is supplied in rolls with measured length. Among the proposals are self-adhesive options. Their back side is covered with an adhesive, which greatly simplifies and speeds up installation.

For pipes, a heater is produced, made in the form of a shell, these are positions called thermaflex, energoflex, and another. It is a finished shell in the form of a cylinder, covering communications.

The thermal conductivity coefficient of foamed polyethylene depends on its brand and is in the range of 0.031-0.051 W / m⁰.

This material is durable, elastic, resistant to aggressive chemicals, lightweight, easy to install, moderately flammable (class G2). In terms of its smoke-generating ability, it belongs to class D3, i.e. produces a large amount of smoke during combustion. Doesn't apply to environmentally friendly materials, because the period of its decomposition is two hundred years.

Depending on the production method, 2 types of polyethylene foam are distinguished:

• PPE or sewn;
• NPE or uncrosslinked (gas-foamed).

The first is superior to the second in all respects, but its price is also higher. The NPE is characterized by the smell of gas. On this basis, it can be distinguished from uncrosslinked polyethylene. Among the disadvantages inherent in polyethylene foam are its high flammability, low mechanical strength and resistance to UV radiation.

Foamed synthetic rubber applications

This insulation, consisting mainly of closed pores, is similar in appearance to cross-linked polyethylene foam. Unlike the latter, it has increased flexibility. Installation technology is the same as for PPE. The same form of release - mats, sheets, rolls, cylinders, but the service life is three times longer.

The rubber cylinders have an inner diameter of 5-300 mm and a wall thickness of 5-150 mm. For easier installation, pipes of large and medium diameters have a longitudinal section.

On the insulated area, the joint is sealed with an adhesive. The thermal conductivity coefficient is 0.024-0.038 t / m⁰. Does not change its characteristics in the operating temperature range -200 / + 175⁰.

It is possible to use the material in rooms with increased sanitary and hygienic requirements. Foamed rubber is moisture-resistant, mold-resistant, self-extinguishing.

The ignition temperature is above 300⁰. In terms of thermal conductivity, vapor permeability, thermal conductivity, tightness of joints, rubber exceeds analogs from polyethylene foam and polyurethane foam.

Polyfoam as insulation for ventilation pipes

Polyfoam is a foamed mass of plastic containing a large volume of gas. This is a rigid material in the form of pipes, consisting of 2-3 parts and connected by means of a thorn-groove lock or plates. Only square pipes are insulated with plates.

The advantages of foam include light weight, resistance to decay, ease of use, low price, service life up to 25 years. The thermal conductivity coefficient fluctuates in the range of 0.032-0.05 W / m⁰. For 30 days, water absorption is 4%. In bending, the ultimate strength is in the range of 0.07-0.2 kgf / m². Working temperatures - -50 / + 75⁰.

Polyfoam is a regular polystyrene foam. It is attractive to rodents, is easily flammable, and releases toxins when burned. For installation, a special glue is required, any other can cause the material to melt.

Extruded polystyrene foam - many protection features

In the production of extruded polystyrene foam, the same raw materials are used as in the production of foam. However, it is precisely thanks to the specific technology that a material is obtained that does not have pores and channels in the structure, into which moisture can penetrate.

For the same reasons, it retains heat better. Produced in the form of rigid tubes or slabs, marketed as Penoplex, EPPS, Technoplex, equipped with tongue-and-groove locks. It has a long service life - up to 50 years.

The thermal conductivity coefficient of polystyrene foam obtained during extrusion is in the range of 0.028-0.034 W m⁰. The 30-day water absorption is 0.4%. Working temperatures range from -50⁰- + 75⁰. Differs in sufficient bending strength - 0.4-1kgf / m².

PirroVentiDuct thermal insulation for ventilation

PIR boards are a new generation of insulation with a rigid cellular structure. It is made from polyisocyanurate foam. The two sides of the PIR board are covered with foil layers. The service life declared by the manufacturers is 50 years. The material is resistant to decay, moderately flammable, but when it burns, it releases toxic substances.

Straight and shaped duct elements based on PIR plates are obtained by cutting the latter, followed by gluing the blanks with a special contact adhesive.

The thermal conductivity of the material is 0.021 W / m⁰. The water absorption index is within 1%. The compressive strength of the plates is 120 kPa.

The procedure for warming ventilation in a cold attic

All thermal insulation measures are carried out in accordance with the norms regulated by SNiP 2.04.14-88. Here are clear instructions on where and how to organize ventilation insulation.

When installing the insulating layer, the main rule should be observed: the insulation should be fastened as tightly as possible so that there are no gaps between the ventilation duct and the insulation. Installation of each of the materials has its own characteristics.

Features of insulation with mineral wool

When insulating with mineral wool, one must not forget that it is hygroscopic.

This fact leaves an imprint on the order of work:

1. The piping in a cold attic is wrapped with a waterproofing membrane, leaving no gaps or crevices.
2. Mineral wool is wound with an overlap, overlapping the previous strips. The thickness of the layer must comply with SNiPu.
3. A layer of waterproofing is wound over the insulation.
4. The entire structure is tightened with special bandages.

A rectangular pipe can be insulated with mineral wool in mats. First, they cut out the blanks of the required sizes, and, overlapping the pipe with them, pull them together with knitting wire, clamp or tape.

In the outer corners of the air ducts with the installation of insulation, certain difficulties arise; it will not be possible to immediately achieve the necessary tightness. Therefore, at the end of the device of the main thermal insulation coating, the remaining gaps are filled with pieces of material.

Ventilation insulation in a cold attic with expanded polystyrene

If the material is in the form of slabs, therefore, they can be insulated with rectangular ducts. The technology of work on insulation is the same as when laying mineral wool. The only difference is the optional waterproofing device. The decision is made based on the density of the insulation material.

So, in the case of using PPS-40, waterproofing is needed, and if PPS-60 is used, waterproofing is optional. Plates should be joined tightly, cracks and gaps should be filled with polyurethane foam.

Thermal insulation with cylinders

Special shells for ventilation insulation are made from many insulation materials:

• mineral wool;
• polyurethane foam;
• expanded polystyrene;
• polyethylene.

They are used in the case of use for a ventilation device for pipes of circular cross-section. There are several types of such thermal insulation:

• one-piece with a longitudinal section;
• two, three, four-section.

The cylinders are selected according to the diameter of the duct. The larger the cross-section of the pipe, the more parts the shell consists of. If it is a one-piece cylinder, it is opened along the cut and put on the duct.

The cylinder is useful as insulation for straight sections. In places where the duct turns, it will not work to put it on. Mats are used in these areas. Among insulating materials of this type, cylinders made of mineral wool, polystyrene and polyethylene have the lowest cost. The most expensive option is a foamed rubber shell.

A very convenient option for insulating ventilation with your own hands is a self-adhesive insulation, i.e. penofol brand "C". On one side of it there is a foil, on the other - a polyethylene film with an adhesive composition applied to it. The adhesive side is protected by an additional layer of foil. Remove it before installation.

The material is cut to fit the perimeter of the duct. At the next stage, the pipe is closed with insulation, folding the edges with an overlap of 50 mm. The joint is sealed with foil tape.

Conclusions and useful video on the topic

How to make insulation of ventilation pipes with your own hands:

Thermal insulation of ventilation pipes with mineral wool and the achieved effect:

In a cold attic, pipes must be insulated without fail. When choosing a material for this purpose, you should be guided by the design features of the house and your financial capabilities. If the ventilation system is properly insulated, it will be extremely functional, and it will last a very long time.

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