To understand how to properly insulate a roof, you need to understand its types. The most common types of roofing structures are the cold attic and the attic. In the first case, insulation of the ceilings of the upper residential floor will be required (the air in the attic space does not warm up, hence the name). In the second - laying thermal insulation along the roof rafters. In today’s article we will analyze in detail the process of insulating the roof of a cold attic.
The cold attic is the most common, time-tested roofing structure, used all over the world for decades. It has become widespread due to its simplicity, availability of materials and ease of installation. In addition, in the cold attic there is access to inspect the load-bearing structures of the roof, so possible leaks can be easily localized and eliminated with improvised means.
Rice. 1. Cold attic insulation system: 1. Floor beams 2. Stone wool insulation 3. Vapor barrier film 4. Super diffusion membrane 5. Sparse lathing 6. Internal lathing
Wooden floor beams and reinforced concrete slabs are most often used as the base for the attic. Depending on the selected flooring material for the residential floor, the insulation system will differ. Wood is one of the best building materials, which has a number of undeniable advantages: lightness, strength and flexibility. However, wood is sensitive to humidity: over-moistened wood during use can bend in an unpredictable way if it picks up moisture and then dries out. Therefore, wet wood is not used in construction, and dry wood is carefully isolated from possible waterlogging during operation.
The ability of wood to absorb moisture affects the choice of all cold attic materials. So, when choosing insulation, you should give preference to a vapor-permeable material based on mineral wool: this material will allow all wet steam to pass through itself, leaving the beams dry. When choosing between glass wool and stone wool, you should remember the ability of the latter to protect the entire structure from exposure to open fire. The sintering temperature of glass wool fibers is only about 600 °C, and this temperature is reached within 5 minutes after the start of combustion. Therefore, only stone wool can protect load-bearing structures, extend the life of a house and, in the event of a fire, give more time to save people and property.
Here it is worth recalling that any organic insulation (foam plastic, polyurethanes) burns, so it is better not to use them when building a wooden or frame house. The combustion of some of them is also accompanied by the release of toxic vapors into the atmosphere, “splashing” of the melt, which poses an additional danger to people. The use of organic insulation in floor construction requires mandatory protection with a cement-sand screed.
The use of various construction films raises many questions in the insulation system. Due to their incorrect location in the structure, floor beams can begin to rot, which is why they subsequently lose their load-bearing capacity and collapse in a few years. To prevent this, when arranging a classic cold attic with wooden beams, it is customary to use two types of building films, which we will conventionally call “Internal” and “External”.
The “internal” film is laid from the inside of the heated room and prevents water vapor from entering the insulation from the room. This film is called a vapor barrier. When installing it, it is necessary to carefully glue all overlaps with butyl rubber tape, achieving tightness over the entire area. Interior finishing is carried out with a technical gap of at least 3 cm - to prevent local moisture condensation on the vapor barrier.
Rice. 2.1. Cold attic ventilation diagram
The “external” film performs other tasks: it protects the insulation from moisture from the outside (snow, rain, fog), allows water vapor to escape from the system (if it suddenly appears there) and prevents heat from being blown out of the insulation. Some of these functions can be entrusted to ordinary plastic film, but it will not be possible to perform all tasks at the same time. Most films either have low vapor permeability - and therefore must be installed with a second ventilation gap, or low water resistance - and therefore do not protect against water getting into the insulation. The only type of film that can solve all the problems at the same time is called a “superdiffusion membrane”. Such a membrane has vapor permeability that significantly exceeds the parameters of the insulation, which allows it to be mounted close to it. And high water resistance allows you to protect the system from external moisture in any form.
Thus, the insulation must be protected by a vapor barrier film from the inside and a superdiffusion membrane from the outside. It is a good practice to lay sparse sheathing of boards over the “top” membrane to prevent damage to the film or crushing of the insulation when walking through the attic.
Figure 2.2. Consequences of lack of ventilation (1 year, Minsk region)
Figure 2.2. Consequences of lack of ventilation (1 year, Minsk region)
Concluding the consideration of the design of a cold attic, it is imperative to pay attention to the issue of ventilation. A properly organized roof ventilation system of a house (Fig. 2.1), despite the possible variety of designs, must have three mandatory components: an entry point, ventilation channels and an exit point. The entire volume of the attic will serve as a channel for ventilation in a cold attic. For normal operation, the temperature inside a cold attic must be equal to the outside temperature. For these purposes, the filing provides entry points for cold air - the so-called “vents”. And in the upper part of the attic you need to create air outlets using dormer windows, ridge or point aerators.
Most often in practice we have to deal with a situation where ventilation is impaired: all vents are sealed with insulation, and air from the street does not get inside. The second common mistake is the absence of dormer windows or aerators in the roof covering. When arranging ventilation, it is worth remembering that the area of the outlet openings should be 10% larger than the area of the inlet openings. In this case, sufficient thrust will be created. If the roof ventilation is impaired, then the rafter system is subject to waterlogging, and the roofing material is subject to additional excess pressure from inside the room. This can lead to rotting of the rafter system and loss of its load-bearing capacity (Fig. 2.2.), and premature destruction of the roof covering. Therefore, effective ventilation is a prerequisite for the normal operation of a cold attic system.
In the case of installing a cold attic on a base made of reinforced concrete slabs, the system can be simplified. Since reinforced concrete is vapor-proof and is not susceptible to exposure to open fire, insulation can be made from organic materials. Here you have to choose from two types of polystyrene foam and polyurethane foam. Polyurethane foams are increasingly appearing on objects, but sprayed compositions do not always have the declared stable properties after hardening, and their strength is sometimes insufficient for the dynamic effects of pedestrian loads. The well-known expanded polystyrene foam (EPS) is still used in construction today. However, it has already been replaced by more modern extruded polystyrene foam (XPS), characterized by lower thermal conductivity (which reduces the required insulation thickness by 25%), reduced water absorption by 5 times and increased strength. When arranging a cold attic using reinforced concrete slabs using XPS, there is no need to spend money on the purchase and installation of building films: the material withstands all external influences and is not afraid of blowing or even soaking.
To determine the required thickness of thermal insulation, we will use the technique that is described in detail in TKP 45-2.04-43-2006 “Construction heating engineering. Construction design standards". According to this document, minimum requirements for the thermal resistance of the structure are established. For a roof, it is taken to be no lower than six, and is calculated by the ratio of the actual thickness of the construction material (in this case, thermal insulation) to its thermal conductivity. Thus, the answer to the question “How to insulate the roof of a house?” - obvious: the required insulation thickness is calculated by multiplying the thermal conductivity of the material by six. This simple mathematics will allow you to create a cold attic that fully complies with all current standards. For complete insulation in our climate zone, 25 cm of stone wool will be required. And when using extruded polystyrene foam, 20 cm will be enough. In a similar way, you can calculate the required thicknesses of other thermal insulation materials. For comparison: to obtain a similar indicator by filling with expanded clay, you will need a layer more than half a meter thick!
In the next part we will tell about the design and proper insulation of the attic (warm attic).
Text: Andrey Povarnitsyn
Insulating the attic floor of a house allows you to retain more heat inside the room, rather than wasting it on heating a cold attic. It’s good if it is used as a utility room (technical attic) or as an attic, but what if not? Then it makes no sense to waste resources on heating an unheated attic space.
That is why it is worth insulating the ceiling of a cold attic using thermal insulation materials. Insulation can be done from the attic side or from the room side (inside/outside). It is best to do this during the construction of the building, or immediately before finishing the room. But even during the operation of the house, there is no reason not to insulate the ceiling from the attic.
The thickness of the attic floor insulation is standardized using SNiP II-3-79 “Construction Heat Engineering”. This manual contains detailed recommendations regarding the selection and formula for calculating the heat transfer resistance of various thermal insulation materials. The calculations take into account not only the type of material, but also the average annual temperature, the duration of the heating season, and the wall material of the house.
The technology for insulating the attic floor depends on the selected material.
In this article we will look at the most popular insulation materials.
Mineral wool is an insulation material whose fibers are arranged in a certain way. It is this randomness that leads to the formation of an air cushion between the fibers, which imparts its properties to the insulation. However, this same feature of cotton wool increases its ability to absorb moisture. To avoid this, you need to know how to install mineral wool correctly.
Advantages of mineral wool:
- high density;
- long service life;
- Fire safety;
- ease of installation;
- the use of mineral wool for insulation of horizontal surfaces does not lead to caking, sliding and, as a result, the formation of cold bridges.
Among the disadvantages: the ability to absorb moisture.
There are three main ways to lay cotton wool: completely, in grooves or in cells (see photo). The choice of method depends on what load will subsequently fall on the floor. The most stable frame is obtained in the latter case.
First stage
It starts with laying a vapor barrier film. The film will allow you to remove steam that rises from a warm living space into a cold attic. To lay the film correctly, you need to carefully read the markings on it. It is imperative to maintain an overlap of 100 mm.
If insulation is carried out along wooden beams, then the film should go around all protruding elements. Otherwise, the beams may rot.
At the junction of the film and walls or other protruding surfaces, you need to raise it to a height equal to the thickness of the insulation plus 50 mm. and glue it with tape or wrap it on an insulation board.
Second phase
The insulation (cotton wool) is being laid. It's a pretty simple process. Plates or strips are easily cut with a construction knife to the required sizes.
When laying the sheet, you need to make sure that there are no gaps or the mineral wool material is not too compressed. Both will lead to a decrease in the quality of insulation. Typical mistakes in photos.
a) insufficient thickness of thermal insulation material;
b, c, d) the thickness of the attic floor insulation is incorrectly selected.
- insulation with foil will increase the material’s resistance to heat loss. The sheet is laid with the foil side down.
- the insulation should not protrude beyond the beam. If such a situation arises, the beam must be extended with a wooden beam or additional batten to the thickness of the insulation.
- Thin insulation laid in two layers retains more heat than one thick one. In this case, the slabs must be laid in a checkerboard pattern.
- if there are protruding structural elements in the attic, for example, a chimney pipe, you need to raise the insulation to a height of 400-500 mm. and secure it.
Third stage
Waterproofing is installed if the attic is not intended to be used and the rafter system is not protected by a waterproofing film. If the roofing material is separated from the attic with film, then you can proceed with the final stage.
Rough floor. It is laid on top of the insulation and serves as the basis for the final finishing.
The installation technology process is similar to insulating an attic floor with polystyrene foam.
The advantages of these materials:
- low cost;
- ease of operation;
- waterproof.
Among the disadvantages: flammability.
Technology for insulating attic floors with polystyrene foam or polystyrene foam
The process of installing rigid insulation based on it is more than simple and can be done with your own hands. The work can be divided into two stages:
- surface leveling. To ensure high-quality insulation, there should be no significant unevenness on the base floor. Such differences can be eliminated by screeding with sand-cement mortar.
- The slabs are laid end-to-end or between beams. The presence of timber increases the strength of the floor.
Tip: carefully seal any seams, incl. joints with beams. When going around an obstacle, try to cut the holes as accurately as possible. A homogeneous thermal insulation layer retains heat better.
Rough coating
Polystyrene foam must be protected from destruction with film in an uninhabited attic. In a frequently used or residential attic, you need to move somehow, so it is better to install an OSB subfloor on top of polystyrene foam or expanded polystyrene or use a sand-cement screed.
Sawdust is finely ground wood.
Advantages:
- naturalness;
- absence of toxic impurities;
- light weight;
- availability of material.
The disadvantage is flammability.
Technology of attic insulation with sawdust
- Before you start insulating them with sawdust, you need to prepare them. Namely, mix cement and water with sawdust in a ratio of 10:1:1.
- Pour the prepared mixture onto the attic floor and level it. It is worth noting that sawdust can only be used as insulation without using a frame in a non-residential attic. Otherwise, when walking on the floor, the sawdust will be compressed and the concrete screed will collapse.
- build a cellular structure from timber. Pour a solution with sawdust inside each cell. The advantage of this method is that a subfloor can be laid over the timber. And the attic will be usable
Expanded clay is produced by firing clay.
Advantages:
- low thermal conductivity;
- naturalness;
- environmental friendliness;
- ease;
- availability.
The disadvantage is associated with the difficulty of lifting expanded clay to the height of the attic.
Expanded clay is usually used when it is necessary to insulate the attic floor using slabs.
Technology of attic insulation with expanded clay
The work is carried out in three stages:
- The slab is inspected for the presence of cracks and cracks. They are sealed with mortar or covered with thick paper. Protruding elements do not create difficulties with filling expanded clay.
- install timber sheathing. In the future, a subfloor will be laid on it.
- loose insulation is poured onto the slab and leveled using a regular rake. Layer thickness 250-300 mm. You can move on expanded clay without restrictions.
Tip: when filling expanded clay, it is better to combine granules of different sizes (diameters). This way you can avoid the appearance of voids.
Finally, a subfloor is installed or filled with sand-cement screed.
Please note that insulating an attic wooden floor has some nuances:
- the tree is susceptible to rotting, which means the steam rising to the top must pass freely. Improper installation of films or the use of non-breathable materials, such as roofing felt, will lead to the destruction of wood in the future.
- When using foil insulation, you need to place it with the foil down. This way the wood will be protected from water and at the same time will not accumulate steam moisture.
- The “correct” way is to use a superdiffusion membrane or vapor barrier film
- “Wrong” - laying a special film without taking into account the markings or even ordinary film
The attic floor insulation diagram for various types of insulation is shown below.
Conclusion
In this article, we focused on the main stages and features of insulating the attic floors of a private house using various types of insulation. We hope this information is useful to you.
To insulate or not to insulate a cold attic? It would seem, why worry about additional insulation if this is not a residential attic? The cold attic itself - the space between the floor of the house and the pitched roof - plays the role of an additional air gap in the thermal insulation of the building. But it alone is not enough to prevent the penetration of cold and hot air from the street into the room. Maintaining a comfortable temperature inside the building and minimizing heating costs is possible only by protecting the horizontal ceiling from freezing - a kind of “fifth wall” in the thermal circuit of the house. We'll tell you how to do this in our review.
Technology and ecology
What is usually used to insulate a cold attic? In an effort to save as much as possible on building materials, many use ordinary sawdust, believing that it is an environmentally friendly and affordable insulation material. But in addition to being labor-intensive to install, they are highly flammable and therefore a fire hazard. Another significant drawback is that they can harbor rodents or insects.
Another popular material used for attic insulation is polystyrene foam or polyurethane foam. Does not rot, is not afraid of corrosion, holds heat well. But at the same time, it does not allow water and steam to pass through, due to which condensation can form in the under-roof space, which is completely unacceptable.
It is absolutely fireproof, vapor permeable, does not shrink and absorbs sound waves well. And its improved environmental characteristics and service life of more than 100 years make it an undoubted favorite for those who build a reliable home for themselves - with love and attention to detail.
Installation stages
Flooring with wooden joists is the most common type of flooring in a private home. Experts recommend maintaining a distance between lags of 600 mm (along the axes) or 580-590 mm “in the clear”. If these standards are observed, the installation of thermal insulation boards 600 mm wide occurs without waste and unnecessary effort for trimming, between the joists.
The thickness of the thermal insulation layer is calculated taking into account the characteristics of the construction region, as well as the purpose of the building.
Also, when installing thermal insulation, it is important not to forget about creating a vapor barrier so as not to let warm air vapor from the living room into the system. The vapor barrier should be laid from the ceiling side and hemmed from the bottom of the wooden logs - this will protect not only the mineral wool, but also the wooden logs from moisture. To be sure of the tightness of the vapor barrier layer, the sheets must be laid with an overlap of at least 100 mm and the seams must be taped.
From below, the ceiling can be hemmed with large-sheet material: OSB-3 boards, plywood or plasterboard.
In order to maintain the energy efficiency of stone wool slabs for a long time, it is necessary that moisture is promptly removed from the material if it enters the attic space. For this purpose, experts recommend laying a wind- and moisture-proof vapor-permeable membrane in the upper part of the “pie”. However, this is not a necessary condition, especially if the membrane is already laid in the roofing slope.
Important! Vapor barrier film is not allowed to be laid on both sides of the insulation. This can lead to waterlogging of the material inside the system and loss of the thermal insulation properties of GreenGuard UNIVERSAL boards.
As you can see, installation is very simple and does not take much time. And competent, fireproof, environmentally friendly attic insulation will help maintain comfort in the house for many years. from insulating your home with GreenGuard UNIVERSAL slabs right now!
To make the under-roof space of a private house warm and even habitable, it is necessary to insulate the attic from all sides - along the gables and roof slopes. This is quite a difficult and troublesome task, given the slopes of the attic walls to which the insulation will have to be attached. Here it is important to maintain the technology so that the thermal insulation “pie” lasts for decades and at the same time retains heat well. Therefore, the question of how to properly insulate a cold attic with your own hands is worth considering in more detail.
Insulation options
Before considering the list of materials, it makes sense to clarify what the concept of “insulating an attic” means, since the choice of insulation depends on this. Some homeowners put into this concept the insulation of the ceiling and the hatch into the attic in order to reduce heat loss in the house, and the under-roof space itself will remain cold. Others mean thermal insulation of roof slopes from the inside with insufficiently insulated ceilings, as was done in old houses using clay.
Still others want to make the attic space usable and warm, which again requires insulation of the attic walls, which are roof slopes and side gables. It is this kind of thermal insulation that will be discussed in detail below. If we are talking about insulating the floor of a cold attic, then the choice of materials here is quite large:
- expanded clay;
- wood waste (sawdust);
- glass wool in rolls (such as ISOVER or URSA);
- slab or rolled mineral wool (ROCKWOOL, KNAUF);
- slabs made of foamed polymers (foam plastic, extruded polystyrene foam).
Note. The list does not include options for insulation with polyurethane foam and ecowool due to their high cost, but we have listed the most popular materials for attic floors. In addition, you won’t be able to insulate the attic floor with sprayed polyurethane foam yourself without special equipment.
Now, from the list presented above, we will highlight those insulation materials that are most often used to insulate sloping attic walls. In terms of cost, foam plastic is the cheapest, and its thermal resistance is high, as is its ability to repel moisture. One problem is that the material is flammable. Therefore, for those homeowners who are concerned about the fire safety of their home, it is better to buy mineral wool based on basalt fiber. Only mineral wool absorbs moisture well, so you will need to provide for its removal, which will be discussed below.
A few words about glass wool, which is also quite suitable for thermal insulation of an attic. It also does not burn, but it cannot withstand high temperatures either; the material becomes charred at 200 °C or more. If you plan to make the attic space residential, then glass wool has no place there at all, it is harmful to human health.
Insulation with mineral wool
As mentioned above, mineral wool is a porous material that can absorb moisture and also allow vapor to pass through it. Even if this insulation is protected on both sides with a vapor-proof film, then due to the temperature difference outside and inside the house, a dew point will appear in the thickness of the wool. As a result, condensation will begin to form from the air that is already in the open pores of the material.
When insulating an attic with mineral wool with your own hands, you need to learn one rule: the insulation is insulated from moisture only on one side - the inside, and a ventilation gap (vent) is required on the outside. Thanks to it, moisture will be removed from the wool, thereby maintaining its thermal insulation properties.
Also, glass and mineral wool are afraid of direct contact with water, which is why they instantly get wet and cease to be insulation. This means that on the street side it must be protected from wind and precipitation, while ensuring that water vapor escapes in the same direction. This is why it is more difficult to insulate an attic with mineral wool than with foam plastic, which is vapor-tight. The diagram below shows the correct “pie” of thermal insulation of the inclined walls of the attic from the inside:
As can be seen in the diagram, the insulation is laid in the openings between the rafters, but first a waterproofing film - a diffusion membrane - is laid between the rafter boards and the roofing. It is this that protects the mineral wool from direct moisture, allowing all vapors to pass out into the air, from where they are carried away by ventilation air. The vent should be arranged under the entire plane of the roofing, as shown in the diagram:
Since the diffusion membrane is at the same time a protection against water that can enter its surface from the outside through cracks in the slate, the film sheets should be laid out horizontally on top of the rafters, starting from the bottom. The canvases are laid with an overlap of 100 mm, and the joints are sealed with tape. When it comes to insulating an old house, where the slate is nailed to the sheathing boards without a membrane, you will have to install it in strips vertically between the rafters.
Important. The membrane strips must be fastened to the side surface of the rafter board using a stapler and as often as possible, leaving a 5 cm wide air vent on top.
The next stage is laying the insulation directly into the gap between the rafters, for which it is cut into strips whose width is a couple of centimeters larger than this gap. By the way, mineral wool manufacturers make slabs 600 mm wide and rolls 1200 mm wide, adapting to the standard spacing of rafter boards. In this case, additional fastening of the insulation is not required; then a vapor barrier film is laid and the interior finishing is installed.
Like the sloping walls of the attic, the gables also need insulation. But here the composition of the “pie” depends on the building material of a given roof element. If it is made of brick or timber, then it would be more correct to insulate the gable of the attic from the outside, guided by the following diagram:
It is clear that such thermal insulation implies external insulation of the entire house, which is not always possible for various reasons. Then we continue to insulate the attic from the inside, vertically installing wooden beams on the brick wall for further installation of insulation. Before doing this, do not forget to lay a diffusion membrane under the beams. The same is done if the pediment has an old structure - a wooden frame with outer cladding made of clapboard. The insulation “pie” then looks like this:
Note. The same “pie” is used for internal insulation of the brick gable of the attic. The masonry here plays the role of the outer cladding made of boards, shown in the diagram.
Foam insulation
It should be noted that insulating an attic with polystyrene foam is somewhat easier than with mineral wool. Primarily due to the vapor permeability of this insulation, so it is not necessary to install an internal vapor barrier. But a diffusion membrane and ventilation are needed in any case, because wood also participates in the “pie,” which must also release moisture somewhere. So the first stage of do-it-yourself attic insulation is repeated as described in the previous section.
Foam plastic with a density of 25 kg/m3 is cut so that it can be tightly inserted between the rafters. Then all joints should be blown out with polyurethane foam, which prevents air circulation through the cracks and provides additional fastening of the insulation. Then everything is simple: the interior trim made of plasterboard or other facing material is attached to the rafter boards.
Thermal insulation of gables is carried out in the same way. It should be noted that this technology can also be used when insulating an attic with extruded polystyrene foam (penoplex). This modern insulation has higher performance than polystyrene foam, including strength. If there is a need to lay penoplex in 2 layers, the second can be attached to the first with ordinary self-tapping screws and glued with polyurethane glue.
Insulation of ventilation pipes in the attic
In modern private houses, the attic is often a technical floor where ventilation units and pipes for moving air - air ducts - are located. If the temperature there is significantly lower than in the premises, then the air ducts must be insulated and here’s why:
- The air passing through them is heated by energy carriers paid for by the homeowner. It is unacceptable for air to waste heat in a cold attic;
- due to temperature differences inside and outside the air ducts, condensation will constantly be released.
The cheapest way to insulate ventilation pipes is to buy rolled mineral wool and wrap it around the air duct, securing it with twine.
After which the layer of mineral wool is covered with special foil to prevent moisture from entering. But when compressed, the thermal resistance of rolled insulation is reduced, so it is better to use ready-made foam shells. They are placed on the air duct on both sides and secured with knitting wire.
It is most convenient to insulate rectangular ventilation pipes with self-adhesive foam polyethylene material. This is an excellent vapor-tight insulation, one side of which is covered with a sticky layer that adheres well to the metal surface.
Conclusion
In fact, there are more materials and methods for insulating an attic, but we have listed the most affordable ones for doing it yourself. For example, a layer of polyurethane foam does not require any “pie” at all, but it can only be applied if you have special units. So at the moment, polystyrene foam with mineral wool remain the most popular insulation materials, as well as the technology for their use.
If you need to turn a cold attic in a private house into a living space: a children's or guest room, a workshop, a gym, it is not necessary to add a floor with a new roof. You can turn a pitched roof into a classic attic. This is much simpler than constructing a capital superstructure, and also cheaper. We tell you how to insulate a cold attic.
We insulate the attic correctly
Differences between an attic and an attic
The main difference is in the insulation system and the method of ventilation of the space. In the first case, the floor of a cold attic is insulated, and ventilation occurs using a ventilation chamber. An example diagram of attic insulation is shown in the photo.
1 - Wooden rafter system
2 - Stone wool insulation
3 — Vapor barrier film
4 — Superdiffusion membrane
5 - Sparse sheathing
6 - Sparse sheathing of the ceiling of a living space
7 - Sparse sheathing and wooden decking with roofing
In the attic - using energy-saving materials. Ventilation of the roofing pie occurs as a hinged ventilated facade, with the help of counter beams that create channels for air movement and removal of moisture from the structure. Flexible tiles are used as a roofing layer, which do not fade in the sun and do not deform under the influence of temperature and precipitation. It is also necessary when constructing roofs with complex geometry and the presence of protruding elements: roof windows, pipes, antennas, aerators.
1 — Wooden rafter system 2 — Vapor barrier film
3 — Stone wool insulation 4 — Superdiffusion membrane
5 — Counter beam for creating a ventilation duct 6 — Sparse sheathing
7 — Wooden flooring 8 — Underlayment carpet 9 — Mastic for gluing flexible tiles 10 — Multilayer tiles
Choice of insulation
The material for insulating the attic of a private house can be polystyrene foam, basalt wool or polyurethane foam; often even ordinary sawdust is used - a very dangerous solution in the event of a fire. Good insulation, especially for a wooden house, must have a whole range of additional properties: fire safety, vapor permeability, resistance to rodents and mold.
Modern manufacturers have a range of slabs for stone wool. This is a lightweight, hydrophobized, non-flammable heat and sound insulating material. In addition, ecowool is based on natural components with improved environmental characteristics and a service life of more than 100 years. Thanks to the optimal density ratio and random arrangement of fibers, the slabs do not shrink and absorb sound waves well.
Step-by-step plan for attic insulation
1. Dismantling the old roofing
After dismantling the old roofing, you need to check the condition of the rafter system. It may need to be increased. Then check the structures for fungal and insect damage. If these problems exist, they should be changed. Treat all wooden structures with an antiseptic. It will protect the wood from insects, fungus and mold, and when exposed to critically high temperatures or fire, it will not allow the wood to maintain combustion.
2. Attaching the vapor barrier film
Installation of the future attic wall begins with attaching a vapor barrier film to the rafters on the inside of the room. The overlap of the material must be at least 10 cm. You can attach the film to the rafters using a construction stapler, and create a continuous vapor barrier using a special acrylic tape. This tape is used to glue the film sheets together and gluing them to walls and passage elements.
3. Preparing the base
Next, wooden boards are nailed on top of the vapor barrier film from the inside of the room at intervals of about 15 cm. They will serve as the basis for the interior decoration of the room.
4. Laying insulation
Effective installation is carried out from the outside of the roof. The insulation scheme is very simple: the insulation is laid in three layers in the space between the rafters.
The recommended distance between the logs in this case is 600 mm (along the axes) or 580-590 mm “in the clear”. The width of the insulation slabs is 600 mm, which allows you to lay the material in spacers, without waste and unnecessary effort for cutting. The thickness of the thermal insulation layer is calculated taking into account the characteristics of the construction region, as well as the purpose of the building.
It is important to ensure that the joints between the layers are made staggered, this will avoid possible gaps in the thermal insulation. It is recommended to use stone wool, since this material is non-flammable and easy to install. At the same time, the thickness of the insulation is small.
Before laying in the area of the eaves overhang, it is necessary to attach a transverse board between the rafters, which will prevent the insulation from falling out of the under-roof space.
5. Laying a hydro- and windproof membrane
The membrane does not allow moisture-saturated warm air vapors from the living room to pass into the system. It is attached to the rafters with a construction stapler, allows steam to escape well from the roofing structure and protects the insulation from getting wet and swelling of the top layer. It is recommended to install the membrane from the eaves overhang up to the ridge, with membrane tapes overlapping at a distance of at least 10 cm and the seams must be taped. From below, the ceiling is hemmed with large-sheet material: OSB-3 boards, plywood or gypsum plasterboard sheets.
It is very important not to lay vapor barrier film on both sides of the insulation. This can lead to waterlogging of the material inside the system and loss of the thermal insulation properties of the slabs and the entire floor.
6. Creation of a ventilation system
To create the entire length of the rafters, bars with a cross section of 5 cm are nailed or screwed on top of the membrane. This allows you to create the necessary ventilation duct from the eaves to the ridge to remove excess moisture. Thanks to this, there will be no ice formation in the under-roof space in winter, and the insulation will retain all its energy-saving properties. It is important to take into account that bars with a cross section of 5 cm are relevant when the slope is inclined more than 20 degrees. If it is smaller, then a block with a cross section of 8 cm will be required.
Sheathing boards are mounted horizontally on top of the bars, on which the boardwalk will then lie. The sheathing pitch is approximately 30 cm, selected depending on the thickness of the solid wooden flooring.
7. Installation of plank flooring
The last stage before installing a flexible tile system is the installation of a boardwalk made of moisture-resistant plywood or OSB-3 board. When laying the flooring, it is necessary to leave a gap of 3-5 mm between the slabs - it compensates for the expansion of the slabs under the influence of temperature and moisture.
8. Laying flexible tiles
It is produced using the same technology as for any pitched roof. Detailed step-by-step instructions for laying flexible tiles on board flooring can be found on our website or in the video.
Thanks to stone wool insulation, OSB-3 board and flexible tiles, the structure has high noise insulation and energy saving properties. And the problem of insulating the floors of a cold attic is solved in a few days.