Many owners of old houses are thinking about expanding their living space by adding an attic. However, they immediately wonder what to do if the roof is already covered, but the attic still needs to be insulated. In this case, the decision to carry out insulation work from the inside comes to the rescue.
Peculiarities
The process of insulating an attic from the inside cannot be called easy. To do this, you need to know the specifics of the roof structure, as well as understand whether your existing roof is suitable for insulation. Indeed, not every attic can be converted into an attic space, especially if the roof is already covered.
There are three situations in which the roof can be constructed:
- There is only a ventilation gap between the rafters and the sheathing. In this case, the roof is considered completely unsuitable for insulation. You will have to completely disassemble the roof structure to insulate it.
- A polyethylene film is laid between the sheathing and the rafters, acting as a vapor barrier. Such solutions can be considered optimal, and the roof can be considered fully prepared for subsequent insulation work.
- A diffusion membrane is laid between the rafters and the sheathing. Option similar to the previous one. The presence of a waterproofing layer is evidence that the roof is prepared for insulation from the inside.
Thus, the most important feature is the preparedness of the roof for further insulation.
Insulation materials
Thermal insulation of the roof of a private house, summer house, or cottage can be done using various means. There are liquid materials, elastic ones, and even those that have a relatively high density.
Before you start making your choice, be sure to pay attention to the roof structure. It often happens that not every material is universal, so it is better to be safe. The simplest example is the insulation of gable and sloping roofs: if almost any insulation is suitable for a simple gable structure, then not all of them are suitable for a sloping roof.
If we do not consider liquid insulation, the rest are sold in two forms - in slabs and in rolls. As you might guess, the slabs contain dense insulation, while the rolls contain fibrous insulation.
It should be noted that Not all options available on the market are suitable for insulation from the inside.. This is due to the fact that it is much more difficult to insulate the attic from the inside due to the existing rafters. This increases the need to level cold bridges.
Materials for internal thermal insulation should be considered in more detail.
Styrofoam
Ordinary polystyrene foam is one of the cheapest materials. It is sold in ready-made slabs, which makes it easy to use. Despite the fact that polystyrene foam is a budget thermal insulation solution, it has many advantages.
So, polystyrene foam is not hygroscopic - it absolutely does not absorb water and moisture. To increase water-repellent characteristics, it is enough to treat it with a special agent., which will clog the pores on the surface, and water will simply flow down the foam boards.
It should also be borne in mind that polystyrene foam has a very low weight due to the presence of a large number of voids between the granules that make it up. This makes it possible to handle the insulation work alone. Lightness has the further advantage of easing the load on the roof structure.
Polystyrene foam does not conduct heat well, as a result of which we can safely say that it perfectly insulates the attic. The ease of working with it is another significant advantage of the material: you can cut the material, cutting out pieces of the desired size, with an ordinary stationery knife.
However, there are also some disadvantages. Firstly, the foam does not “breathe” at all, which can cause condensation to form. Secondly, polystyrene foam is susceptible to damage by pests, in particular rodents. Third, wooden floors cannot be decorated with polystyrene foam, since over time the wood will shrink and gaps will appear between the foam boards.
How to insulate an attic with polystyrene foam is described in the following video.
Penoizol
Penoizol, or urea-formaldehyde foam, is a liquid version of polystyrene foam. The insulating solution is prepared immediately before use. Its difference from many other installation compositions, for example, polyurethane foam, is that during the hardening process it does not expand, maintaining its original appearance and condition.
The mass resembles white foam, similar in appearance to shaving foam.
Liquid foam is often used to insulate roofs and attics during the construction phase, but can also be used after the roof has been laid. Among other things, it can be used to additionally insulate the walls and floor of the attic.
The vapor permeability of the material, like that of its dense counterpart, is almost zero, which makes it imperative to take care of adequate roof ventilation. However, the material does not conduct heat, so it copes with its main function – thermal insulation – perfectly. So if you do all the work properly, thermal insulation using foam insulation will be a worthy and budget solution.
Extruded polystyrene foam or penoplex
Despite the fact that polystyrene foam and expanded polystyrene belong to the same group, the second is more practical. This is largely due to the specifics of installation. So, polystyrene foam covers the rafters, which results in better tightness. Expanded polystyrene boards are easily fixed to each other using glue. Due to its low weight, installation can be done independently.
The material has a long service life, but it does not rot and is not attacked by rodents. The only serious drawback is the flammability of the material. You will have to take care of additional insulation of the electrical wiring, because one spark can lead to a strong fire.
If no communications are planned for the attic, expanded polystyrene will be an excellent choice, especially considering that it can be covered with any finishing material. It is also compatible with wood, metal, and any roofing coverings.
Minvata
Mineral wool often acts as an alternative to penoplex. This material is a roll material, which is due to the ease of installation of heat insulators supplied in this way. Mineral wool has a fibrous structure, which fundamentally affects some of its properties.
So, mineral wool is an elastic material that is attached between the rafters. In this case, additional fastenings are not required, it is enough to just cut the wool slabs 2-3 cm wider than the portal into which the insulation will be inserted.
Rodents do not attack cotton wool, so you don’t have to worry about the integrity of the insulating layer. Mineral wool, however, belongs to the category of environmentally friendly insulation. Among other things, it guarantees excellent thermal insulation, despite the fact that it does not absorb moisture, and even if it gets wet, it will dry in record time. It is also better to use fibrous material if it is necessary to additionally soundproof the attic from surrounding street noise.
Read more about insulating the attic with mineral wool in the next video.
Glass wool
Glass wool is one of the varieties of mineral wool, but the difference is obvious. First of all, it is worth noting that the materials are made from different fibers. Fiberglass is used here. Thanks to this, the material is more elastic and durable. In addition, glass wool has better noise-absorbing characteristics. At the same time, it is hydrophobic - it absorbs moisture well, but dries poorly, as a result of which, when wet, it quickly loses its performance properties.
Many are afraid that the use of glass wool for thermal insulation purposes within a living space will lead to harmful consequences. Actually this is not true. If all finishing work is carried out correctly, then no harm will be caused to health. On the contrary, glass wool is even safer than penoplex because it does not burn.
However, the material requires care when laying it. It will be necessary to take all safety measures, protecting the organs of vision, respiratory tract and skin from glass dust.
Stone wool
Among all insulating wools, stone wool is more expensive than its analogues, and all thanks to its special properties. Compared to others, it itself is safe and practically devoid of the disadvantages inherent in other samples. It is the most environmentally friendly of all, it is not afraid of elevated temperatures, since it does not ignite, and also does not deform under the influence of heat.
Stone wool perfectly blocks all extraneous sounds, while its sound-absorbing characteristics are an order of magnitude higher than those of other wools. Another advantage is the good vapor permeability of the material. It “breathes”, so condensation cannot form on it.
Stone wool can last for a long time. Such good performance properties are due not only to the strength properties of the material, but also to its ability to resist mechanical stress. Even if you squeeze it, it does not deform.
Cotton wool is sold in the form of soft slabs that can be easily cut into desired formats if necessary. The only existing drawback is the high price, but the material is worth the money.
Ecowool
Ecowool is very different from other wool in the form of sale. If other analogues are supplied in rolls or slabs, then ecowool is first crushed and then applied by spreading the material using special equipment. It is believed that this way it will better seal all existing cracks, forming a monolithic insulating coating.
There are two disadvantages here. Firstly, you need to apply ecowool using special tools. Secondly, the cost of the material cannot be called affordable either.
Polyurethane foam
Foamed polyurethane foam also needs to be applied using special devices, which are quite expensive.
To avoid unprofitable purchase expenses, it is easier to lease equipment - rent it.
The use of equipment and the application technology itself are quite complex, so when working with the material it is necessary to have at least some experience and knowledge on this issue.
Polyurethane foam is most similar to polyurethane foam because it has a similar operating principle. It expands in the same way when it hardens, completely closing all the cracks and gaps through which cold wind can penetrate or precious heat can escape. After hardening, the material becomes monolithic and smooth. This feature indicates that it does not absorb moisture, so you can do without the construction of additional hydro- and vapor barrier layers.
All this makes polyurethane foam an ideal choice, regardless of what material the roofing and ceilings are made of. The optimal solution when working with it is to invite a team of specialists who will complete the installation in a few hours using their own equipment, doing everything in compliance with technology.
Penofol
Penofol is the only foil insulation of its kind. It is produced in the form of slabs of polyethylene foam, coated with an aluminum layer on one or both sides. Aluminum reflects heat, returning it back into the room, so heat loss is minimized.
However, it is important to ensure that when laying, the foil side is facing inward to the room and not outward.
Penofol is absolutely safe for humans and animals, although it is not a natural material. Thanks to the aluminum coating, it does not conduct heat, which gives grounds to assert the excellent thermal insulation properties of the material. Among other things, there may be no need to make a vapor barrier for this material, since if installed correctly, it copes well with vapor barrier itself due to its special texture.
If you plan to use the attic for permanent residence, then you will not regret choosing penofol.
Preparing the premises
Having decided to insulate the attic from the inside, you first need to properly prepare the room itself for work. Keep in mind that not every attic is suitable for insulation. Check whether the ceiling height is 2.5 m in more than 50% of the entire attic area. If not, then there’s no point in insulating it – you won’t be able to live here anyway.
Next, remove all existing sheathing material, exposing the rafters. The insulation will be installed either on top of them or between them. Check the condition of the roof, as well as the presence of vapor and waterproofing layers. Keep in mind that a roof with leaks must first be corrected, and only after that can you proceed to insulation work.
It is important that they are in good condition and have no cracks other than for ventilation.
Vapor barrier
When creating an attic floor for winter living, especially if the winters in your area are harsh, the first thing you need to do is check for a vapor barrier. As a rule, it is done immediately when the roof is installed, even if there are no plans to use the space under it as an additional room in the future. If there is no vapor barrier, then the roof will have to be redone from the outside, dismantling the roofing materials. Unfortunately, it is impossible to lay a vapor barrier layer from the inside, because it must lie between the rafters and the counter-lattice.
Various materials can be used to create a vapor barrier. All of them have their advantages and disadvantages, as well as specific combinations with insulating materials. All this must be kept in mind when moving on to insulation work, so it makes sense to dwell on vapor barrier materials in more detail.
In addition, this will help you make a choice if the roof of your house does not yet have a vapor barrier layer.
Polyethylene film
Despite the cheapness of the material, many builders strongly do not recommend using it. This is due to the fact that it is unsuitable for creating a vapor barrier layer in Russian realities. The material does not “breathe” at all: it does not let in not only moisture, but also air, and this creates problems with circulation and, accordingly, the greenhouse effect. Thus, condensate cannot evaporate and, flowing down, ends up on the thermal insulation.
Therefore, if your home has a vapor barrier made using polyethylene film, avoid purchasing water-absorbing insulation materials, such as glass wool.
Over time, the film tends to deteriorate and crack, so after a short period of time you will still have to completely disassemble everything in order to replace the fragile material that has served its purpose.
Glassine
Glassine is suitable for both steam and waterproofing, which is why it has received universal recognition. However, we will have to act in two directions here. Firstly, a layer of glassine will need to be laid between the roof and the counter-lattice, and secondly, on the insulation from the side of the room. If all work is done correctly, this will guarantee reliable protection and an optimal microclimate in the attic. On top, between the roofing and the counter-lattice, a double layer of glassine should be laid. Only then can the optimal effect be achieved.
Glassine is mostly needed to protect the insulation from moisture, so any material can be chosen as an insulation material. Try to choose options that do not deform under the influence of temperature changes, and are also not susceptible to rodent attacks. Both cotton wool and penoplex options are perfect.
Ruberoid
Ruberoid has been used as a vapor barrier since the times of the USSR, so in old houses you can find just such material between the roof and rafters. Nevertheless, If possible, such a layer will need to be dismantled. This is due to the fact that roofing felt is a rotting material, and in accordance with the standards it cannot be used for waterproofing and vapor barrier in buildings with a long service life.
If you decide to leave the roofing material, then you should not expect good vapor barrier qualities from it. For this it is better to lay an additional layer of special vapor barrier material, at least the same plastic film.
It is worth keeping in mind that condensation may accumulate on the roofing felt on the inside, which will lead to the insulation getting wet. So, if the insulation is temporary (for example, it is carried out in winter, and in the spring it is planned to redo everything), then foam plastic can also be combined with roofing felt.
Izospan
The material isospan consists of polypropylene. It is one of the most recommended for the construction of vapor barriers due to the fact that it was developed only for these purposes.
Izospan collects condensation and subsequently prevents it from getting on the insulation. The double-sided texture of the material is responsible for this. On one side it is smooth, and on the other it is a little rough. On the rough side, condensate droplets are retained and evaporate. With the help of isospan, not only the roof, but also the walls of the attic are vapor-insulated.
Depending on the properties of isospan, the labeling varies. The most expensive, but also materials with energy saving effect FB, FS, FD, FX are considered effective. They have a foil coating that reflects heat back into the room, thereby reducing heat loss to almost nothing. At the same time, the special texture still prevents condensation from rolling off and damaging the insulation.
Waterproofing membrane
You should not attribute to waterproofing membranes all the same properties that are inherent in specialized vapor barrier films. Indeed, both of them collect and evaporate condensate, but the main task of waterproofing membranes is to protect the house from moisture, and not from steam. In addition, waterproofing membranes have a wider range of applications: from insulating attics and basements to protecting swimming pools.
Waterproofing membranes are available in different types. There is diffusion, super-diffusion, and also anti-condensation, which is more suitable than others for a vapor barrier role. If you find one of these membranes after disassembling the cladding material, consider yourself very lucky.
You can lay any insulation without fear that it will get wet and quickly lose its quality. In addition, the microclimate in the attic will be excellent.
Penofol
Penofol is both an insulating and vapor barrier material. However, it can only be laid when a waterproofing membrane is found between the roof and rafters.
The reflective foil surface itself will collect condensation and help it evaporate, but the second “bare” side should be well protected from moisture. Only in this case will the variety cope with both steam and thermal insulation.
Material consumption
The calculation of the material is made at the stage of inspecting the roof for damage. Here it is important to take into account the pitch between the rafters and the distance between the vapor barrier and the internal space. The number and thickness of the slabs depends on the internal space: whether the thermal insulation will be laid in one layer or in several. The size of the slabs depends on the distance between the rafters.
Please note that if the pitch between the rafters is more than 60 cm, then you will need to prepare additional sheathing yourself to make fixing the thermal insulation possible.
As for sprayed insulation, in this case it will be necessary to calculate the volume. You will first need to clarify such data as the expected thickness of the thermal insulation layer, the perimeter of the rooms and the height of the walls, as well as the density of the insulation. We must not forget about the presence of windows and doors. It is best to use a special calculator.
Insulation scheme
Since when insulating an attic, the roof is mainly insulated, it makes sense to consider the layering scheme only for it.
If you start from the outside, the pie will look like this:
- There is roofing material on top that is not touched. Underneath it there is a sheathing and a counter-lattice, which serve as a frame.
- Next comes a layer of hydro- and vapor barrier, which is also the original one.
- A layer of insulation is laid under the waterproofing. Depending on the width of the step between the rafters, additional sheathing can be constructed here.
- A vapor barrier layer is attached to the side of the room to protect the insulation.
- Finally, finishing is done.
How to insulate with your own hands?
To insulate an attic with your own hands from the inside, you need to keep in mind the plan for placing the layers one after another, and also follow the following step-by-step instructions:
- It is necessary to retreat slightly from the existing waterproofing layer, leaving an air opening. This will allow the insulation to “breathe”.
- After this, the insulation is installed. Depending on the material, it can be laid between the rafters or on them, or sprayed. How it is necessary to handle this or that insulation material is written in the instructions for it.
- Next, install a vapor barrier film. If a gap between it and the insulation is possible, then the connection to the walls, ceiling and, in the case of an attic, to the floor should be airtight. Otherwise, condensation will form on the side of the film that faces the insulation, but this should not happen.
- At the last stage, finishing is carried out. You can choose from many options, but usually purchase drywall, lining or MDF boards.
- It is better to buy cotton insulation not in rolls, but in mats, so they will not require time to “track”;
- to insulate the floor you need to choose polystyrene foam or other inexpensive material;
- the insulation does not require additional fastening, but if necessary, you can use nails, adhesive tape or a construction stapler for this.
Attics first appeared in France, where the famous architect F. Mansara began to use attic spaces that had been empty before him. He organically integrated an ordinary attic into the overall style of the house, placing living rooms or utility rooms there.
The attic allows you to expand the living space and gives the house expressiveness and comfort.
Attics are not only useful in terms of expanding living space, but also significantly affect the overall appearance of the house, giving it greater expressiveness and comfort. In an average house, their area is about 90 m2, that is, this is not a small space; several rooms can be perfectly located there. An attic in a wooden house looks especially organic. But, despite the wonderful properties of this room, it is worth remembering that it is the room that comes into most contact with the environment, and therefore needs thermal insulation the most. The insulation of the attic in a wooden house will be discussed further.
General requirements for insulation
When building an attic, it is worth remembering that it is through the roof of the house that the main heat losses occur, so the attic must be insulated extremely carefully, using suitable materials and using the best technology. Experienced craftsmen know how to insulate an attic in a wooden house; the well-being of the entire house depends on their skills and experience.
Poor insulation of an attic in a wooden house means not only cold, dampness and a disgusting microclimate, but also rotting of the wood, its deformation and destruction.
But full-fledged thermal insulation is unthinkable without combining it with equally high-quality hydro- and vapor barrier; only the union of these three qualities can give warmth and comfort not only to the attic itself, but to the entire house.
The space under the roof not only has a large area of contact with the external environment, which means it suffers maximum heat loss, but is also most susceptible to problems such as condensation. This means that, in addition to insulating the attic, the owner of the house needs to take care of good ventilation. Thus, the entire complex of measures for insulating the attic is a multi-step and complex process, especially when taking into account the structural complexity of this space.
If possible, it is advisable to carry out insulation not only from the inside, but also from the outside.
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Insulation of the roof of a wooden house
largely depends on how well you insulated the attic. If everything is done well, then in the very top part of the house you will always be cool in summer and warm in winter. Among other things, high-quality roof insulation also means absorption of external noise and comfortable silence inside the house.
A roof is not only a roofing covering supported by a wooden frame, it is also an insulating pie that is located between them. It includes:
- correctly selected layers of vapor barrier layer that protects the entire structure from moisture;
- insulation that helps dry air not let heat out in winter and in in summer;
- a waterproofing layer that protects the remaining layers and the entire house as a whole from the penetration of moisture from the atmosphere;
- The air gap between the layers also plays an important role in both ventilation and thermal insulation of the room.
These requirements show that the insulation of the attic space must be calculated at the design stage of the entire house, and not at the moment when you decide to use the room under the roof for your needs. A well-insulated roof will not allow the penetration of cold air from the street, because when it comes into contact with the warm air of the house, drops of condensation are formed, accumulating in various places (rafters, ceiling, space between the layers of the pie). And this is already the beginning of the end. Accumulating moisture is a terrible enemy for any home, but especially for a wooden one. This will entail an increase in the cost of heating the house, since due to high humidity, heat loss will increase sharply, as well as much more dangerous consequences - rotting and destruction of wooden structures.
It is clear that only an experienced builder can carry out such work efficiently, but a beginner can also do this if he does not skimp on materials and follows all the requirements and advice of manuals and instructions.
But what material to choose for insulation?
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The choice of insulation and its characteristics
So, let's start choosing insulation to insulate your attic.
The best insulation in terms of its characteristics is mineral wool.
- Many homeowners insulate their attic floors using foam sheets. The advantages of this material include low price and weight, the latter is important for those houses where it is necessary to avoid unnecessary load on the structure of the building. But still this is far from the best choice. After all, polystyrene foam has one very significant drawback - it is a flammable material, and for insulation it is highly recommended to use fireproof building materials. In addition, polystyrene foam is not suitable as insulation due to low vapor conductivity, which means that it will not be able to pass accumulating water vapor, increasing the humidity of the room. Polystyrene foam is also characterized by its low strength and the fact that it provides comfortable housing for rodents.
- Extruded polystyrene has characteristics that are more attractive than polystyrene foam. It resists moisture well, has low thermal conductivity, thanks to pre-made grooves in the sheets of material, its installation is very simple and convenient. But, like polystyrene foam, polystyrene foam has low vapor permeability. In addition, its price is unreasonably high.
- The next most popular is glass wool. The advantages of such a material can be listed for a long time - these are excellent thermal conductivity, ease of installation, the absence of organic compounds in the composition, which means a long service life, good vapor permeability, absolute fire safety of the material and much more. But there are also disadvantages: glass wool is dangerous when working with it, since small particles of glass from crumbled cotton wool, penetrating the mucous membrane of the eyes, respiratory tract or skin, cause itching, an allergic reaction and irritation. Therefore, installation can only be carried out in special clothing, glasses and a gauze bandage. Moreover, glass dust is not easy to get rid of, so it is better to simply throw away all your clothes; washing will not help.
- The best option is mineral wool, or more precisely, basalt wool. It is less dangerous than fiberglass, but at the same time has no less advantages as insulation. Mineral wool has excellent sound-absorbing properties, in addition, it will last you much longer than fiberglass. Experienced craftsmen prefer to work with this material.
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Insulation of the attic gable
Insulation of the roof has already been discussed above; this procedure is done during construction, but in addition to the roof, the attic also needs insulation of the gable and floor.
- Internal insulation of the attic gable begins with the installation of beams on the gable walls. The distance between them should correspond to the width of the insulation used.
- The first layer is a layer of waterproofing with good vapor permeability.
- The next layer is the insulation itself.
- Then there is another layer of vapor insulation, and you can cover it with finishing materials.
In general, this simple scheme includes the entire process of insulating the gable, but, as in every complex process, it has a lot of nuances that will affect the overall efficiency.
Try to install without damaging the material, with minimal seams and in strict accordance with the instructions.
If the attic space remains uninhabited, the air in the under-roof space serves as good thermal insulation (along with insulation of the ceiling). In the case of the attic, everything is completely different: here the thermal insulation is very close to the roofing material and the task is not only to insulate the attic, but also to create such conditions that the entire roofing system will serve for a long time.
Let us say right away that all wood that is used in the construction of the roof must be treated with antiseptics. Indeed, everything: battens and counter-battens, and rafters. All wooden parts. It is also necessary to make them less flammable. To do this, they are treated with fire retardants. All elements located on the street side are treated with compounds for exterior work. Treat all wooden parts facing the interior with impregnations for interior work. If you use a composition for outdoor use indoors, the specific smell will remain for several years. If it’s the other way around, the wood outside may be damaged: the degree of protection is insufficient. Therefore, do not save on this matter.
More. Before describing how to insulate an attic roof with your own hands, it is worth recalling this: a ventilation system must be organized in the under-roof space. For this purpose, special ventilation holes are installed on the ridge. Through them, air escapes from under the roofing material, carrying away excess moisture. And it must get under the roof deck through the overhangs. There is absolutely no way to do everything hermetically. This is where the air intake comes from. This is the only way the condensate will dry out in a timely manner and the roof will last a long time.
Proper insulation of the attic
To ensure that the attic floor is warm in winter and cool in summer, there are no problems with high humidity, and icicles do not freeze on the roof, it is necessary to properly insulate the roof. But in the case of roofing, insulation, vapor and waterproofing are a complex solution and one without the other works very poorly, or does not work at all.
If the sloping roof is also the walls of the attic floor, the pie will be as follows (from inside to outside):
- internal cladding (plasterboard or lining);
- sheathing;
- vapor barrier;
- insulation (the thickness of the insulation depends on the region and the parameters of the insulation; for central Russia it is about 200 mm);
- superdiffusion membrane;
- ventilation gap;
- sheathing;
- roofing covering.
The photo shows the insulation of a sloping attic roof in a graphical version. Please note: a superdiffusion membrane (indicated in blue) is placed above the insulation. Its purpose is to prevent formed condensation or precipitation seeping through the roofing from entering the insulation and to remove the steam that did get into the mineral wool, ensuring its drying. Therefore, with vapor permeability from 1500 g/m2. This layer is often called waterproofing (that’s what it actually is), only the waterproofing is vapor-permeable.
Laying waterproofing
Ideally, it is laid exactly as shown in the figure: wrapping the rafters and laying closely on the insulation. Often, to save money, it is rolled out over the rafters, but not by pulling it, but by making a sag of 3-5 cm. This option also works well: moisture gets to the surface, and then rolls down and is removed outside the roof. Here is another important point: the membrane must extend into the drainage gutter. Then moisture will be removed from the under-roof space.
A few more points on laying the membrane. It rolls out across the rafters, starting from the bottom. The first row runs into the gutter. The next one rolls out with an overlap of 10-15 cm. And so on until the ridge. At the ridge, the membranes on both sides are cut along the upper edge and secured. A strip rolls along the ridge, going down from one side and the other of the roof. This creates a coating along which water flows all the way to the drainage gutter.
Vapor barrier and rules for its installation
It is worth talking separately about vapor barrier. This should also be a membrane. Polyethylene or polypropylene film will not work: its characteristics are not the same. The vapor permeability of this layer (expressed in g/m2) should be minimal. Ideally, it is equal to zero. That is, this layer should not allow vapors to pass from the room into the insulation layer. When using mineral wool as insulation, this is very important: when it gets wet, it loses more than half of its properties, and when it freezes in a wet state and then melts, it completely crumbles into dust.
Therefore, the vapor barrier film is also laid with one panel overlapping the other. Moreover, these joints are glued with special double-sided vapor-impermeable tape (it looks like adhesive rubber). An ordinary painter's or stationery tool will not work. They do not provide 100% steam protection. In addition to the joints, all junctions are also glued: from below, from the sides, from above.
There is a line marked on the vapor barrier. It marks the border from which the next layer begins (this is the amount of overlap) and the line along which the canvases are fastened with tape
The vapor barrier is usually attached to the joists using staplers or, as in the figure, with internal sheathing slats for installation of the sheathing. In this case, another ventilation gap is formed, which will dry out the finish and membrane. This gap is desirable, but not required. In principle, the lining can be mounted directly on top of the membrane.
Thermal insulation
How best to insulate a sloping roof is a complex question and there is no clear answer to it. Mineral wool is used, only hard, with a density of 30-50 kg/m3. Since the attic roof usually has a large angle of inclination, soft materials can slide. It is for this reason that it is better to take slabs. Although in this case you will have to adjust the pitch of the rafters to the size of the insulation: it should be 10-15 mm less than the width of the slab so that the material fits between the beams and holds well.
Thermal insulation must be laid so that there are as few cold bridges as possible. For central Russia, 200-250 mm of mineral wool is usually required. These are several layers of mats. When laying between rafters, the slabs are positioned so that the seams of one row overlap the next. The width of the insulation, as already mentioned, should be slightly wider than the distance between the rafters. Then the slab becomes tight, eliminating the presence of cracks. If the width is larger/smaller, you have to cut the material. In this case, the chance of getting a smooth edge is small and there are a lot of residues left.
If the size of the rafters does not allow laying all the insulation, planks of the required thickness are stuffed across the side of the room. The remaining insulation is placed between them. A vapor barrier and, if necessary, lathing for finishing are already attached to the top. This option is even better: cold bridges are completely eliminated, even covering the rafters. This method requires slightly higher installation costs, but the attic will definitely be warmer, which will reduce heating costs.
How to insulate an attic roof: work order
The good thing about the attic floor is that it allows the completion of construction to be extended. It is immediately necessary to lay and secure the superdiffusion membrane on the rafters, along with the sheathing and roofing material. And insulating the attic can be done from the inside after some time.
But please note: the waterproofing layer must be installed together with the roofing. This is the main mistake of many developers: they do not install this membrane. As a result, it is either necessary to remove the roof and lay it, or to invent systems to correct this deficiency. The whole problem is that in this case there is no cheap solution that guarantees the normal condition of the materials.
We insulate from the outside
If you do everything at once, the order of work is as follows:
With this option, working with insulation is not difficult: it is easy to lay, it rests on the sheathing (laces).
Insulation from the inside
This option allows you to postpone the interior finishing for the required period (useful if there is a shortage of funds). After installing the rafter system, here is what you need to do:
- roll out and secure the waterproofing;
- fill the sheathing (if necessary, counter-lattice);
- install roofing material.
For the first stage, this is all the necessary work. Once you are able to continue, you will need to insulate the attic roof from the inside. It will no longer be so convenient to work: you will have to make an enclosing structure that will prevent the insulation from being pushed out higher than necessary. The cotton wool itself will have to be fixed somehow: it tends to fall on your head. The order of work is as follows:
A few notes on how thermal insulation material can be laid. If these are mats made of high-density mineral wool and their width is slightly larger than the pitch between the joists, everything is relatively simple: they themselves hold up well.
If rolled mineral wool is installed, everything is more complicated. When insulating the attic roof from the inside, it is laid from bottom to top. Take a lace and a construction stapler. Roll out the cotton wool, press it against the slats, fasten a piece of lace with staples, drawing the letter Z. This is how you secure the first layer, followed by the second and all subsequent ones.
In general, if you want the attic roof to be warm, it is better to use mineral wool mats of the required density of 30-50 kg/m3. They are tough enough to hold their shape well. Softer rolled materials on vertical surfaces or with a large slope cake, settling down, and the thermal insulation of the attic roof deteriorates.
What is the best way to insulate an attic roof?
As mentioned above, the most popular material for insulating an attic roof is mineral wool. She is good, but not at all ideal: she is afraid of moisture. That is why it requires such careful protection from all sides so that it retains its properties.
Foam plastic (expanded polystyrene)
The roof is sheathed with foam plastic or extruded polystyrene foam - EPS. Polystyrene foam (grades PSB-S-25, PSB-S-35) has good characteristics, but when burned it emits harmful substances, although there are self-extinguishing brands (with special additives). It is better to use them for roof insulation.
The main advantage of polystyrene foam: low price. It is easy to install: it is placed between the rafters, all joints are sealed with polyurethane foam. It is convenient to insulate the attic from the inside with polystyrene foam: you order slabs of the required size - 10-15 mm larger than the clearance between the rafters - and place them tightly. Due to their elasticity, they hold up very well.
A ventilation gap is also left on the roof side and waterproofing is installed. But it protects the wooden structure more, since polystyrene foam is not afraid of moisture, practically does not absorb it, and does not conduct steam. This is where the main drawback lies. Since the material does not allow steam to pass through, a good ventilation system is needed in the attic, and this is an additional cost.
EPPS has the best characteristics: under equal conditions, its thickness is two times less than mineral wool of the specified density and one and a half times less than that of polystyrene foam. It also has a locking system that reduces the risk of gaps through which heat can escape. Another plus: extruded polystyrene foam is not liked by mice and insects; fungi and mold do not grow on it. What limits its use: a respectable price. You also need a ventilation system.
EPS brands - Extrol, STIREKS, PENOPLEX, URSA XPS, Technoplex, PRIMAPLEX (PRIMAPLEX), Styrofoam (Styrofoam), KINPLAST (KINPLAST), Teploizolit, GREENPLEX (GREENPLEX). Although the technology is the same, there are some differences in characteristics, so compare when choosing.
Not long ago, a new type of insulation appeared: expanded polystyrene foam. It is applied in liquid form to the surface, reacting with air, increasing in size many times over, filling all the cracks and forming a monolithic layer. This is, perhaps, the only way today to correct the situation and efficiently insulate the attic if, when installing the roofing, they forgot to lay a layer of waterproofing.
Ecowool
This insulation has good characteristics (thermal conductivity coefficient 0.036-0.040 W/m² °C), but has a special application technology. It is necessary to organize a closed cavity into which the composition will be poured. In the case of an attic roof, the side parts are rafters; sheet material (fibreboard, gypsum fiber board, plywood, etc.) is nailed to them from below and above.
A feeding sleeve is launched into the formed cavity, from which loosened cotton wool emerges under pressure. It fills all cavities, forming a single layer of insulation.
The main advantage of ecowool compared to all the insulation materials described above: it conducts vapor. It can absorb moisture up to 20% of the volume and then release it. That is, there is no need to organize a vapor barrier: humidity is regulated naturally, as is the case with wood. The ventilation gap between the roof and the insulation should be the same, as should the properly organized movement of air masses in it.
The attic is the favorite home of poets, artists, artists and creative people. Thanks to new building materials, the attic floor can be used as a room under the roof as a living or utility room (zone) not only in summer, but also in winter (for winter living). Abroad, well-designed and decorated attics even fall into the category of bohemian housing.
In modern housing construction, an attic is not just an equipped warm attic, it is an effective way to increase the functional space of a residential building. It is noteworthy that, in accordance with urban planning standards, the attic is taken into account when determining the number of storeys of a building.
Advantages of an insulated attic:
- saving on the cost of materials during the construction of a residential building;
- arrangement of functional additional space;
- original appearance of a private house with an attic;
- reduction of heat loss through the under-roof space.
Disadvantages include: sloping ceilings, the need for additional insulation, difficulties with the rational organization of living space.
Most of the disadvantages of an attic are completely removable and, with the right approach, become advantages.
Preparing to insulate the attic
A specific feature of the attic is the presence of a sloping ceiling. Moreover, according to SNiP 2.08.01-89 “Residential Buildings”, the height of the attic floor cannot be lower than 2.5 m. It is allowed to reduce the height in an area not exceeding 50% of the total area of the room.
Other features of the attic include:
- dependence of heat loss on the material from which the house is built: wood, cellular concrete, brick or a combination of them;
- dependence of the attic engineering systems on the existing ones in the house. This leaves its mark on technical solutions for communications;
- variety of architectural forms: broken, single, gable roof;
- variety of design solutions. The material for the manufacture of load-bearing elements of the attic can be wood, metal, reinforced concrete;
- specifics of the location. The attic can be located within the building area or extend beyond its boundaries, supported by columns or a cantilevered extension of the interfloor ceiling.
Thus, when deciding how to insulate an attic for winter living, you need to proceed from the design features.
Please note that it is correct to carry out work on insulation of a residential building or apartment outside the premises, because... This approach ensures that the freezing point shifts towards the insulation mounted on the outside of the wall.
However, insulating the attic from the inside is a widespread option, because... all surfaces that are subject to insulation are located inside the attic (room) floor - ceiling, floor and walls. The exception is the pediment, which can be insulated as part of the attic insulation or along with the insulation of the entire house.
Factors affecting the thermal insulation of the attic
Professionals identify two key factors that have a significant impact on the level of heat loss and operational characteristics of the attic after insulation work has been completed.
- Firstly, it is a thermal insulation material. Taking into account the fact that the attic floor is the coldest room in the house, and it is intended to insulate the attic with your own hands, you need to carefully approach the choice of insulation.
- Secondly, it is a waterproofing film. It is precisely this that is designed to protect the insulation from moisture entering the attic premises from the outside (outside), through the roofing material, and from the inside, through the floor.
Which insulation for the attic is better to choose?
To insulate the attic of a house, you can use any heat-insulating material that has proven itself in practice.
Among the most popular materials are: cotton wool, polystyrene foam, polyurethane foam and their varieties. It should be remembered that insulation for the attic is selected taking into account factors inherent to a particular house and taking into account the level of skill of the person who will install the insulating material.
The characteristics that determine the suitability of insulation for use in a particular case are given in the table.
| Insulation | Stiffness (compressive strength) | Thermal conductivity | Hygroscopicity | Shrinkage | Weight | Installation on a broken roof | Price |
|---|---|---|---|---|---|---|---|
| Mineral wool (basalt insulation) | - | - | + | + | - | + | 100-140 rub/sq.m. |
| Glass wool (synthetic insulation) | - | - | + | + | - | + | 70-80 rub/sq.m. |
| Penofol (foil insulation) | - | - | - | - | - | + | 40-50 rub/sq.m. |
| Ecowool (cellulose insulation) | - | - | + | - | - | + | 23-35 rub/kg |
| Polyurethane foam (PU foam) | + | - | - | - | - | + | 170-212 rub/kg |
| Styrofoam | + | - | - | - | - | - | 2560-3200 rub/m3 |
| Expanded polystyrene (penoplex) | + | - | - | - | - | - | 3500-5000 rub/m3 |
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How to insulate an attic from the inside
Features of the use of insulation of different types and types.
Soft thermal insulation materials:
- Insulating an attic with mineral wool requires careful selection and use of films. Thus, the main disadvantage of cotton wool can be eliminated - its hygroscopicity. The second, less significant disadvantage is slight rigidity, which can be eliminated by securely fixing the cotton wool, as well as the use of denser varieties. This prevents sagging of the wool. Nevertheless, thanks to the environmental friendliness of the components, insulating the attic with mineral wool from the inside continues to hold its leading position;
- Insulating an attic with glass wool is rarely done due to the fact that glass wool is an unsafe material from an environmental point of view. Plus, it creates installation difficulties;
- insulation of the attic with penofol. It is used when it is necessary to insulate without significant losses in the height of the room. In order for penofol to perform its functions, the material must be oriented with a foil layer into the room.
Rigid thermal insulation materials:
- insulation of the attic with polystyrene foam. An excellent and easy-to-install option, which has the disadvantage of incomplete adhesion of the sheets to the sheathing. Due to this, a space unfilled with insulation appears and the insulation efficiency decreases. In addition, polystyrene foam is flammable and releases toxic substances when burned. And finally, rigid insulation does not allow steam to pass through well. The popularity of polystyrene foam is due to its low price;
- insulation of the attic with polystyrene foam (penoplex) is similar to insulation with polystyrene foam. The difference lies in the presence of a tongue-and-groove fastening system, which, in fairness, does not play an important role in insulating the attic. And also in the greater density of the material itself.
Note that breathable soft insulation materials would be a good option if necessary to insulate a wooden attic.
Sprayed thermal insulation materials:
- insulation of the attic with ecowool. The material is 80% cellulose and 20% wood. Contains a natural antiseptic. This is a completely environmentally friendly material;
- insulation of the attic with polyurethane foam (PPU).
The widespread distribution of sprayed insulation is hampered by their high price, as well as the need to attract specialists and use special equipment. At the same time, as consumer reviews indicate, the price is justified by the high level of thermal insulation. After all, the sprayed material fills the smallest cracks and eliminates sources of heat loss.
The thickness of the attic insulation depends on: the type of roofing material, the height of the room, the presence of a heating system, the location of the insulation and its type.
Recommendation. If a chimney passes through the attic roof, basalt wool should be used. It begins to melt at a temperature of 1000 °C, and does not smolder like ecowool and does not melt like rigid insulation materials (foam plastic, penoplex).
Waterproofing and vapor barrier under insulation
Since wool is the leader among materials for attic insulation, and at the same time it is hygroscopic, there is a need to take care of the wool itself, protecting it with a hydro- and vapor barrier film. Otherwise, the cotton wool will get wet and lose its thermal insulation properties.
For insulation insulation the following are used:
- isospan (20-25 rubles/sq.m.). The vapor barrier film (membrane) has a double layer and surface roughness, due to which condensation is retained;
- polyethylene film (3 rubles/sq.m.). The most affordable waterproofing material in terms of price. But this film does not have the ability to transmit steam;
- waterproofing membrane (30-45 rub./sq.m.). Many manufacturers offer roofing membranes that are distinguished by their ability to simultaneously retain moisture and allow steam to pass through.
- penofol (40-50 rub./sq.m.). Foil insulation.
Do-it-yourself attic insulation technology from the inside
Complex thermal insulation involves performing the following types of work:
- insulation of the attic roof;
- insulation of the attic ceiling;
- insulation of the attic floor;
- insulation of attic walls.
Each stage has its own characteristics, which we will dwell on in detail. Insulation of the attic from the inside is carried out if the roof is already covered.
Insulating the attic roof
It doesn’t matter what roofing material the rafter system is covered with. The main thing is that it effectively copes with the task of preventing water from entering the attic space. From the point of view of insulation, the type of roofing material does not matter - their thermal insulation properties are approaching zero. This means that the most significant heat loss occurs through the roof. Therefore, work on insulating the room begins from the roof of the attic floor.
How to insulate an attic roof from the inside - step-by-step instructions
- installation of waterproofing film or membrane. This is a film that prevents water from entering the insulation, but does not prevent moisture from leaving it. Thanks to this, the insulation does not get wet. The film is mounted from the ridge to the eaves in such a way that water, if it gets through the roofing material or condenses on it, flows out over the film. Before installing the film, it is important to treat the wooden parts of the rafter system with a deep penetration primer;
- air gap. It is obtained by arranging the lathing. Allows the material to “breathe”;
- installation of insulation. Mineral wool (or rigid insulation) is laid between the rafters of the attic roof. If the rafter pitch is more than 600 mm. it is necessary to make additional lathing even before the stage of laying the waterproofing film.
The cotton wool is placed end-to-end between adjacent beams or metal profiles, so that there are no gaps. If any appear, you need to cut out a piece of cotton wool and close the gap.
Craftsmen recommend using mineral wool mats rather than rolled material, because... they are more dense. It is also recommended to lay the wool in two layers with an offset. To ensure that the cotton wool sits tightly in the intended place, it can be strengthened with rope or nails;
Advice. If you are insulating an attic ceiling with a slope length of more than three meters, you need to make wooden jumpers between the vertical beams of the sheathing. Because The cotton wool can “slip”.
- installation of vapor barrier film. The purpose of this film is not to let steam into the insulation. The optimal level of humidity is achieved by ventilating the room;
Note. To insulate the rafters, some craftsmen install thin insulation between the vapor barrier film and the finishing material.
When laying layers in a given order, it is important to ensure reliable adhesion of films and insulation to the ridge, valley, walls, window openings, etc.
- finishing material. Most often, sheets of plasterboard, MDF or wood (board, lining) are used to decorate the attic. The facing material is attached to the rafter system or frame made of profiles.