Ceiling insulation methods in a house with a cold roof

Ceiling insulation methods in a house with a cold roof

A lot has been said about the insulation of buildings in recent years. The Russians rushed en masse to insulate the facades of their homes and even the foundation. But for some reason they rarely remember about the ceiling. And it is completely in vain, because the heat loss of a house through the roof can reach 20%. Therefore, the arrangement of thermal insulation in the attic not only retains heat inside the house, but also significantly saves heating costs..


Even from school, it is known that hot air rises up and cold air goes down. This happens due to convection and leads to the fact that all the heat accumulated in the room will enter the unheated attic through the unheated ceiling, and from there go outside. Thus, the heating system of the dwelling begins to work on “heating the street”.

It is for this reason that the thermal insulation of the ceiling requires a more thorough approach than the insulation of facades: the heat loss of wood reaches 3W / m2 / K, and for floors in a brick or concrete house this figure is even higher. That is why the insulated ceiling will become the best protector of the house in the cold season..

However, in summer, its relevance is no less significant. Under the influence of high temperatures, the roof heats up and transfers heat inside the room, completely negating the effect of using air conditioners.

A layer of thermal insulation retains heat well, preventing overheating of the internal space.

At the same time, most of the old houses have a cold roof; in the Soviet years, buildings were built quickly and easily, and there was no choice of reliable materials. The roof in such structures is, in fact, a system of wooden rafters, on top of which a layer of waterproofing and the main roofing material are laid..

Installation of a new insulated roof structure requires a significant investment of effort, time, and most importantly, funds, so not everyone can afford to dismantle the old roof and build a new one. In this situation, the optimal solution is to insulate the ceiling either from the attic or from the living rooms..

Another advantage of the insulation is associated with its good sound absorption.. Thus, the material will not only form a healthy temperature regime in the house, but also protect household members from the sounds of rain, hail or wind..

Having once spent on attic insulation, you can extend the life of the entire roofing structure in the house and significantly improve the microclimate in residential premises for many years to come..

By the way, keep in mind that if the ceiling is insulated from the attic side in the house, then additional insulation of the floors of the first and second floors is not required.

The better to insulate?

Nowadays, the construction market offers a wide selection of various materials for ceiling insulation – from the most modern – mineral wool and polyurethane foam, to thermal insulation options that came from antiquity with clay, sawdust and hay..

Each technology has its own advantages and disadvantages. Let’s dwell on them in more detail.

Materials (edit)

Almost any composition is suitable for ceiling insulation, as well as all types of polymer tile coatings, such as mineral wool and penoplex.

High-quality insulation must meet the following criteria:

  • Any, even minimal, release of harmful and toxic substances under the influence of high temperatures and ultraviolet radiation is unacceptable.
  • The material must be hygroscopic, resistant to moisture, otherwise its operational parameters will be significantly impaired.
  • The insulation must be resistant to combustion – that is, it is very difficult to ignite or not ignite at all. Fire regulations require the material used to contain the spread of fire for at least 25 minutes..

All types of heaters can be conditionally divided into several groups:

  • polymeric materials;
  • fiber insulation;
  • sprayed heat insulators;
  • free-flowing compositions.

The most popular materials for ceiling insulation are shown below..


Mineral wool is widely used in construction work. Insulation parameters meet all the necessary technical requirements for thermal insulation materials.

The use of cotton wool in residential buildings is due to its environmental safety – it is made only from natural materials (limestone, diabase, dolomite or basalt).

The advantages of the material also include resistance to adverse weather conditions and flammability..

At the same time, mineral wool has its drawbacks, namely:

  • tends to absorb water, therefore, when installing it, it is necessary to lay a layer of waterproofing, and additionally treat the seams with a sealant or foam;
  • laying requires a lathing frame, which leads to additional costs of effort, time and money;
  • fiber insulation has a relatively short service life – their effectiveness lasts for 10-15 years, and then the heat insulator needs to be replaced.


Ecowool is made from cellulose fibers. This material has appeared relatively recently and is not yet as widespread as mineral wool, but it is obvious that this is only temporary..

Its advantages are as follows:

  • This insulation is lightweight, greatly facilitating installation work, and also contributes to more reliable thermal insulation of the ceiling.
  • Ecowool is resistant to moisture, mold does not appear in it and fungi do not multiply.
  • In addition, the canvas undergoes a special treatment with fire retardants, therefore it is considered a material that is resistant to fire – it is a low-combustible and self-extinguishing material..
  • The covering, which forms ecowool, is dense and seamless, it is optimal for protection from winter cold and summer heat.

Cellulose fibers are breathable, so the insulation does not interfere with free air circulation, helps to remove condensation and create a healthy indoor climate.


Modern heat-insulating material, which consists of polyethylene foam and aluminum foil. The coating is widely used for finishing unheated balconies and loggias.

The advantages of penofol are obvious:

  • it has a low thermal conductivity, which means it helps to save costs for heating the house;
  • prevents the penetration of draft, cold air and radon into living quarters;
  • has a low weight, which greatly facilitates installation and at the same time does not create additional load on the floors and supports of the building.

However, the disadvantages are also significant. The surface of penofol is flexible, therefore, the mandatory installation of the frame is necessary. It is not suitable for all types of surfaces. Most often, penofol is used together with mineral wool, this contributes to more effective insulation of the ceiling.


Polyfoam, also known as expanded polystyrene, is considered one of the most convenient materials used for thermal insulation of surfaces. It creates effective protection against cold and heat, but at the same time does not harm the health of the inhabitants of the house. If the installation is done correctly, the foam retains its performance characteristics for many years..

Its advantages include:

  • hygroscopicity;
  • good thermal conductivity;
  • light weight;
  • ease of styling.

Among the minuses are noted:

  • poor combustion resistance;
  • exposure to UV rays and chemicals;
  • instability to mechanical damage.

Polyurethane foam

By its chemical nature, polyurethane foam is close to traditional polyurethane foam, its components provide good adhesion to various types of surfaces, however, special equipment is required for the installation of expanded polystyrene. Therefore, it is not possible to apply it yourself..

The coating, which gives the PU foam, is smooth and seamless, there are no cold bridges. In the frozen form, the coating is completely non-combustible, exhibits thermal insulation characteristics that exceed the same indicator for foam plastic by 1.3 times.

The lack of polyurethane foam is due to the fact that it is destroyed under the influence of UV rays, therefore installation requires additional protection from sunlight.

Expanded clay

This is a fairly common material that is very often used for ceiling insulation in private houses..

Expanded clay is a porous granules made of clay. Such material retains heat well and can last much longer than any other insulation.. Expanded clay is not afraid of water, is resistant to fire and is very durable.

The lack of expanded clay is associated with its weight – the material creates an additional load on the floors and the foundation of the building, therefore it can crumble only if the building is able to withstand the increased pressure without sagging or deforming.

Other varieties

For the decoration of private houses in villages and dachas, methods that have come to us from ancient times are often used..

Our great-grandmothers and great-grandfathers also insulated their houses with materials of natural origin:

  • sawdust;
  • reeds;
  • straw;
  • needles;
  • algae;
  • hay.

Warming with sawdust is, perhaps, one of the most ancient methods of insulating dwellings. Such options for thermal insulation are widespread in regions where the woodworking industry is well developed – there such material can be bought literally for a penny, and sometimes even get it for free..

Its advantages are obvious – it is environmentally friendly raw materials and low weight, and such insulation costs quite inexpensively..

However, the disadvantages are quite significant: sawdust quickly ignites and maintains combustion, eventually rot or dry out. And besides, rats, mice and other rodents may well “look after” fresh shavings as a habitat.

Another option for warming that has come to us from ancient times is the use of clay. In its pure form, it is not used, insofar as to create an effective heat-insulating layer, it is necessary to create a coating with a thickness of 50-70 cm.No wood material can withstand this load, which is why a mixture of clay with sawdust is widely used.

In the Soviet years, many used slag and glass wool to insulate a country house.

Slag wool – material produced from blast furnace slag. This is a cheap heat insulator, but in recent years, most consumers have abandoned its use – it absorbs moisture, and when wet creates an acidic environment that contributes to the destruction of the elements of the roof structure.

Glass wool has not lost its relevance to this day. – it is this material that occupies a leading position in the quality of thermal insulation between all types of mineral wool. This indicator of the material corresponds to 0.03 W / mK. Another advantage of the raw material is its low cost..

However, working with glass wool can be unsafe – particles of the material can damage the skin of a person, and if they get into the eyes or lungs, provoke serious injuries. Therefore, working with this material requires the use of protective clothing – gloves, glasses, raincoat and respirator.

Required tools

To carry out work on the thermal insulation of the attic, it is necessary to prepare all the required tools and materials:

  • directly insulation;
  • wooden bars or metal profiles under the crate;
  • hardware products;
  • vapor barrier coating;
  • construction brackets;
  • dowels;

  • puncher;
  • hammer;
  • screwdriver;
  • roulette;
  • construction knife.

Calculation of the amount of insulation

A century ago, the width of the walls helped to maintain warmth in the room – then it sometimes reached 1 meter! Nowadays, the need to build such walls has disappeared, since a huge variety of materials for thermal and waterproofing of buildings has appeared on the market. Their density forms a reduced thermal conductivity, due to which the heat loss of the living space is sharply reduced.

Therefore, today, when preparing finishing work, another task comes to the fore – the need to save money. That is why, before you go to the hardware store, you should well calculate the amount of insulation that will be needed to effectively create an insulating layer.

The general formula by which you can calculate the required indicator looks like this:

V = L * g, where

V is the volume of the insulation in cubic meters;

L is the calculated perimeter of the working surface in meters;

g – insulation thickness in meters.

When calculating the given parameter, it should be borne in mind that in 2009 the EnUV standard was officially adopted, according to which the heat transfer coefficient of the thermal insulation coating was at least 0.24W / m2xK. This value is provided by a layer of insulation with a thickness of 13 to 40 cm, depending on the materials used and the value of their thermal conductivity.

In addition, the type of buildings should be considered. For example, in European countries, different requirements are imposed on buildings of different types – for old buildings they are less stringent than for new types of buildings..

Preparatory work

Before starting installation work on ceiling insulation, it is necessary to prepare a wooden surface:

  • clear the place where the insulation is laid from debris and dirt;
  • treat all wooden elements with special care with a fire retardant, which will increase its flammability, you should be very careful about applying the composition in the cavity of gaps, cracks and cracks;
  • eliminate all existing deformations and surface damage – small cracks are sealed with putty, and more serious damage is treated with polyurethane foam, the excess of which is then removed with a simple knife.

If the insulation is mounted on a concrete surface, then the preparation looks a little different:

  • inspect the ceiling, remove all peeling and fragile decorative coatings, and then remove dust;
  • slightly expand the cracks found and remove the dirt accumulated in them, then putty or treat with a sealant;
  • treat the surface with a layer of primer.

Installation technology

The technology of installing insulation on the ceiling involves the use of one of two methods.

  • Insulation from the inside – This is the laying of insulation on the ceiling surface from the side of the living quarters, often accompanied by the installation of suspended structures or drywall. Particular attention should be paid to the fact that the total height of the ceiling with this method of installation will decrease by about 10-20 cm.It is very important that the material has good vapor permeability, penofol, as well as mineral and basalt wool, are most responsible for these tasks..
  • Insulation of the ceiling outside – This is the installation of thermal insulation from the attic side. The option is quite profitable and practical, since it does not require any finishing works (except for cases when the premises are planned to be made into a residential attic). The most common materials for this type of installation are polystyrene, foam insol, expanded clay and mineral wool..

The first option is considered less preferable for a number of reasons:

  • the height of the ceilings is significantly reduced, which is already small in old private houses (as a standard in Soviet times, the height of the ceilings was 240-260 cm);
  • inability to use a bulk-type heat insulator;
  • cooling points move closer to the internal floors;
  • the need for repair work in connection with the dismantling of the old ceiling covering.

If the attic is insulated from the outside, then the installation is devoid of all the listed disadvantages. However, sometimes there are situations when insulation from the outside is not possible, so we will consider both options for laying the thermal insulation layer on the ceiling..

From within

Insulation works from the side of the dwelling are carried out in cases when the reconstruction of old-type buildings with ready-made attic ceilings is being carried out or there is no access to the attic.

Overlapping is insulated in one of the following ways.

The first involves fixing heat-insulating materials directly onto the floors using an adhesive solution and additional fastening with dowels. This method is optimal when the floor is made of reinforced concrete..

The sequence of work is as follows:

  • overlappings are primed;
  • prepare an adhesive solution;
  • glue is applied to a plate of heat-insulating material, after which it is pressed against the surface and set horizontally;
  • after the solution has adhered (as a rule, this happens after 2-3 days), the insulation is additionally fastened with dowels with a large cap.

At the final stage, the ceiling is finished.

The second method involves installation on a frame base made of wooden beams or metal profiles. At the same time, the insulation is mounted between the main bearing parts of the lathing and is fastened with bent slats of strong straight suspensions.

The method is suitable for all types of floors.

Both options are highly effective, although the thickness of the coating is often significantly limited due to the desire to preserve the usable space of the living space to the maximum..


The method of insulating the ceiling from the outside is more preferable. It is not surprising, because this method does not steal the height of the ceiling. In addition, the method is good if high-quality repairs have already been made in the rooms, the interior is decorated and the ceiling is made in the form of a decorative stylish structure. Then the inhabitants of the house often do not want to destroy the created “beauty” and spend time, effort and money on equipping a new coating. In this case, it is most preferable to carry out thermal insulation over the ceiling..

The device of a thermal barrier in this way involves the use of materials of any type..

However, it should be borne in mind that working with ecowool and polyurethane foam requires the help of professional teams. But the laying of mineral wool, foam or expanded clay can be done by hand..

If the floor is made of reinforced concrete, then the best option would be expanded clay, covered with a layer of 15-20 cm or foam insulation.

Wooden structures may not cope with heavy insulation, here it is worth giving preference to mineral wool, which not only does not create an additional load on the building’s supports, but also allows you to effectively release condensate. Fiber insulation is attached between the existing beams, after which a vapor barrier is equipped, counter-battens are attached to the beams, which will serve as the base base for flooring boards when installing a floor in the attic or in the attic.

The technology for insulating the ceiling from the attic side differs for different types of materials.

When installing with mineral (basalt or stone) wool or glass wool, in addition to the material itself, you will need boards or metal profiles, tools for cutting insulation and fasteners.

  • To begin with, a vapor barrier film is laid on the floor, while the work must be carried out in such a way that no breaks appear on the surface. The material is overlapped by 15-20 cm, and the seams are reinforced with special tape.
  • A frame made of beams or a metal profile is installed on the base prepared in this way, the distance between the elements of the sheathing should be 2-3 cm less than the width of the fiber insulation roll, the height should slightly exceed the thickness of the insulation. This is very important, since it helps to ensure free air circulation in the future..
  • Then the mineral wool is unpacked and fixed in the space between the battens of the crate.
  • If the insulation is made in several layers, then the material should be fastened in such a way that each subsequent layer overlaps the seams of the previous one..
  • Roofing material or other waterproofing coating is laid on top of the crate (do not forget that there must be free space between it and the mineral wool).

The technology of working with polystyrene looks a little different. Styrofoam is laid in two ways – on glue or on a crate.

  • Installation on a frame is a lot like working with mineral wool. The only difference is that the material is attached to the side rails of the crate with liquid nails.
  • But the description of the technology for working with glue corresponds to the following scheme. To begin with, the surface on which the solution will be applied is thoroughly cleaned of debris, dirt and grease. The coating is thoroughly washed, degreased and then sanded to smooth out any irregularities. If necessary, the overlap is primed. Then the glue is diluted and applied to the foam sheets, after a couple of minutes of waiting, the plate is firmly pressed to the floor surface and held until the required adhesion. Thus, the entire surface is processed, the joints of the material with communications are processed with polyurethane foam or sealant.

Installation of insulation from penoizol does not present any difficulties. To begin with, you need to lay a vapor barrier material, after which the space between the beams is filled with insulation so that the layer thickness is 20-30 cm. Roofing material is additionally laid on the surface of the coating and a plank floor is laid.

Working with ecowool is done in one of two main ways – dry and wet..

  • The dry installation option assumes that the material must be placed in pre-prepared cells of the ceiling. At the same time, the thermal insulation properties of the material are used only by 60-70% of the available.
  • The second method involves the use of professional equipment, which effectively moistens the material and then sprays it over the surface prepared in advance. The method is based on the peculiarity of ecowool, which becomes sticky when in contact with water, as a result of which the material adheres tightly to the floor and reliably adheres to its surface. At the same time, thermal insulation manifests itself more fully, however, this method is impossible to carry out on our own – work requires the use of professional knowledge, skills and equipment.

The minimum layer of ecowool required for effective insulation is approximately 20-30 cm.However, the thickness of the coating may be higher if the work is carried out in a region with cold winters.

The most technologically simple option for insulation is the use of expanded clay, which simply crumbles in the space between the beams on a pre-laid layer of vapor barrier materials. Experts recommend using expanded clay of different fractions. This provides less shrinkage and greater strength and insulation efficiency. For regions of the middle climatic zone, the material is applied in a layer of 20 cm, and for more severe conditions it can reach half a meter.

Sawdust is a cheap and affordable way of thermal insulation. To ensure greater efficiency of thermal insulation, this material is mixed with cement and lime in a ratio of 10x1x1. The components are thoroughly mixed to a dry mixture. Then you need to take 5-10 parts of water, to which a little copper sulfate is added (it acts as an antiseptic). After that, the mixture is kneaded again and applied over the surface..

You can make sure that the composition is ready as follows: for this you need to squeeze a little of the mixture in a fist. If water does not drip from it, then the solution is ready for use..

Useful Tips

The indicated methods of ceiling insulation are the most popular methods of thermal insulation of a room that exist today.. Whatever method and whatever materials you use, there are general requirements for this type of work, which must be followed..

  • Heat insulators that absorb water must necessarily be fenced with waterproofing materials on both sides. It is advisable to use them only in rooms with normal humidity levels. The vapor barrier layer is laid on the side from which the penetration of moisture and condensation is most likely.

  • The required thickness of the insulation depends on the specific natural and climatic zone and is calculated according to the R-index of the structure, which for residential buildings is 4.6-7.3 m2 / kW.
  • There is no 100% moisture protection. Therefore, when insulating the ceiling, always use waterproofing materials..
  • The materials used have their own advantages and disadvantages. Mineral wool is considered the most optimal in terms of price / quality ratio and ease of installation, it is not only low cost and high quality, but also this material contains a minimum amount of harmful substances.
  • The most economical option would be sawdust or expanded clay. However, sawdust is short-lived, and not every building can withstand the weight of expanded clay. Polyfoam is relatively cheap and its thermal insulation properties are beyond praise, but this material emits harmful substances. True, in fairness, we note that their doses are minimal and harmless to health..

Which material to choose and which installation method to prefer is a matter of taste. But in any case, high-quality insulation of the ceiling allows you to maintain a healthy microclimate in your house for many years and significantly save costs for its maintenance..

In this video, you will find a master class on insulating an attic floor with mineral wool.

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