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A set of measures to insulate a house necessarily includes thermal insulation of the ceiling, especially if the attic is cold. The fact is that heat rises, so up to 25 percent of the heat can escape through the ceiling and roof of the house. Therefore, I want to tell you how and how to effectively insulate the floor.
As you know, there are two types of attic flooring:
- Beam;
- Slab.
The insulation technology depends on the type of floor. Therefore, we will consider both options further.
Insulation of beam floors
The process of insulating a beam floor includes several steps:
Step 1: preparing materials
First of all, you need to decide on the choice of insulation. In principle, in a private house in the attic you can use absolutely any thermal insulation material. The main thing is that it is environmentally friendly.
Let's look at the most common thermal insulation materials and their features:
- Mineral wool. This is one of the most common insulation materials. It does not burn, rodents and insects do not grow in it, and it is vapor permeable. The only serious disadvantage of mineral wool is its hydrophobicity.
As for the thermal insulation properties of the material, the thermal conductivity coefficient ranges from 0.077 to 0.12 W/m *K. In general, insulating floors with mineral wool is a reasonable solution. The only thing is to ensure high-quality vapor/waterproofing;
- Styrofoam. It is a light and cheap material, but not without some disadvantages. And the main ones can be highlighted that it, as a rule, burns well and “does not breathe”; in addition, rodents can grow in the foam. The thermal conductivity of this insulation is 0.037-0.043 W/m*K;
- Extruded polystyrene foam. This heat insulator is an improved version of polystyrene foam. As a rule, it contains a fire retardant and has higher strength and moisture resistance.
The thermal conductivity of this insulation is lower than that of expanded polystyrene - 0.036 - 0.040 W/m*K, but it costs several times more;
- Cellulose wool. Another name for this bulk material is ecowool, since it is made of cellulose and is one of the most environmentally friendly insulation materials. Thanks to special treatments, ecowool does not burn and is resistant to various biological negative influences. The thermal conductivity of cellulose wool is in the range of 0.032-0.041 W/m*K;
- Expanded clay. This is another loose insulation material, which is granules of foamed baked clay. The advantages of expanded clay include environmental friendliness and fire safety. However, it has a fairly high thermal conductivity - 0.1 - 0.18 W/(m*K).
Therefore, expanded clay must be laid in a layer at least 25 cm thick, otherwise a good result will not be achieved.
To save money, you can use natural insulation - sawdust or reeds. The only thing is that they will have to be treated with a fire retardant and antiseptic.
In addition to insulation, you will need the following materials:
- Vapor barrier film;
- Superdiffuse membrane;
- Protective impregnation for wood.
Step 2: Preparing the Beams
Preparation involves doing the following:
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Installation of a rough ceiling. To perform insulation from the attic side, the floor must have at least a rough ceiling on which vapor barrier and insulation can be laid. To do this, you need to secure boards or sheet material to the beams from below. |
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Beam processing. Cover the surface of the beams with an antiseptic. |
Now you can start thermal insulation.
Step 3: insulation
Insulation instructions look like this:
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Vapor barrier:
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Laying insulation:
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Waterproofing. Place a waterproofing film over the thermal insulation and beams. As with laying vapor barriers, the joints must be taped. |
At this point the work is completed, all that remains is to complete the attic floor - lay boards or other material on top of the waterproofing.
It must be said that it is possible to insulate the floor from below. In this case, a slab heat insulator is used, which is placed in the same way in the space between the beams. In this case, a fishing line or nylon cord is pulled to fix the plates.
Insulation of slab floors
Insulation of a slab concrete floor also includes three steps:
- Preparation of materials;
- Floor preparation;
- Insulation.
Step 1: preparing materials
Since the insulation will perform a load-bearing function, it must be durable. It is best to use extruded polystyrene foam or polystyrene foam with a density of at least 25 kg/m3. It can also use stone wool in slabs with a density of at least 150 kg/m3 or expanded clay.
In addition to insulation, you will need the following materials:
- Roll waterproofing;
- Materials for screeding.
Step 2: preparing the base
The floor preparation is carried out as follows:
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Surface cleaning. Remove any debris that is on the surface of the stove. |
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Elimination of defects. If there are serious potholes or cracks on the surface, they must be covered with cement mortar. |
Step 3: insulation
Thermal insulation is quite simple:
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Waterproofing the floor.
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Laying insulation. Lay the slabs on the floor close to each other so that there are no gaps. |
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Filling the screed. The screed is poured over the insulation in the standard way. You can get acquainted with the technology of pouring screed from other articles on our portal.
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It should be noted that sometimes it becomes necessary to insulate the ceiling from the inside, for example, in an apartment building. In this case, the heat-insulating boards are glued to the concrete with a special glue and additionally secured with dowels.
When installing the roof of a private house, a space is formed between the roof and ceiling floors of the room, which is called the attic. It can be used as a storage room or a living room or office can be arranged there. In any case, it is worth paying attention to the insulation of the attic space in order to avoid heat loss and the safety of the wooden roofing.
Useful insulation
In practice, no construction innovation in the field of insulation can compete with mineral wool, which has already been proven over the years, which is ideal for insulating a country house. Due to the fact that mineral wool is made from hard rocks, its abilities reflect the thermal insulation properties of the stone. Meter-thick stone walls were replaced by brickwork. It has the following characteristics:
- thermal insulation;
- sound insulation;
- fire resistance;
- vapor permeability;
- environmental friendliness.
The thermal insulation coefficient of insulation is 0.038–0.045 W/Km, which is a rather low indicator. Thus, a protective layer of mineral wool with a thickness of 100 mm can be compared in terms of thermal insulation with brickwork with a thickness of 1170 mm. In this case, the sound insulation coefficient is 0.95 with a maximum value of 1.
Insulating a home with fiber insulation meets all fire safety requirements, since it does not burn at all and can withstand high temperatures.
For a wooden house, the vapor permeability of the thermal insulation material is also a very important indicator.
In this case, you cannot do without mineral wool. It has good vapor permeability and is used for installation of ventilated facades. And the last property of cotton wool is its environmental friendliness: the materials used in production do not have a harmful effect on humans and the environment.
If you plan to install mineral wool in the attic, then before starting work you need to decide on its type (glass wool, mineral wool, basalt slabs), the density of the material (varies in the range from 30 to 200 kg/m3) and the required quantity.
All this must meet the requirements for attic insulation.
Nuances for work
The floor in the attic is also the ceiling of the house, through which heat is lost from the room. Moisture from the warm air below constantly penetrates into the attic and has a negative effect on the fiber insulation.
When wet, it loses its thermal insulation properties, and with prolonged exposure to moisture it quickly collapses. The negative impact of moisture is also noted on the structural elements of the roof. Condensed water on the inside surface of the roof flows onto the rafters and beams. This leads to the destruction of supporting structures.
To protect mineral wool and the internal surfaces of the roof from water vapor, a vapor barrier made of moisture-proof material is used. It is laid between the ceiling and the insulation. It is important that the integrity of the waterproofing is not compromised.
To avoid further formation and accumulation of moisture in the attic, you need to properly organize ventilation. It is arranged through vents placed on the ridges and cornices, as well as through slatted and dormer windows. Ventilation will be quite intense if the ratio of the sum of the areas of the ventilation openings is from 0.2 to 0.5% of the attic area.
Isolation process
Working with insulating wool requires compliance with safety rules and the use of special PPE. If the attic space will not be used as a living room, then it must be made ventilated. Before you start insulating with mineral wool, you need to install ventilation gutters. They are attached under the roof with brackets to the roof frame.
If insulation is carried out using rolled material, then laying a vapor barrier is not necessary, since the wool is in a polyethylene cover. The mineral wool strips should be laid tightly and the edges taped.
In the case of using slabs, insulation is carried out on a pre-laid waterproofing coating.
You need to start insulating with cotton wool from the point farthest from the door, gradually moving towards the exit. If obstacles arise, the canvas or sheet must be cut, and in the next part of the insulation a cutout should be made in the shape of the obstacle. It cuts perfectly with a utility knife. If gaps appear, they need to be insulated with leftover material and scraps. Try not to be overzealous when compacting and bending the mineral wool, as this will negatively affect its heat-insulating ability.
If lighting fixtures are installed in the attic floors, they must be covered with special caps. Although the cotton wool does not burn, the device heats up during operation, and conditions may be created for the wooden floor to catch fire. Next, all that remains is to cover the thermal insulation by installing the floor in the attic. It can be plywood, plasterboard, chipboard or OSB board.
Arrangement of the attic
The roof of the finished attic has the appearance of a layer cake. Exterior covering is a roofing material designed to protect a home from precipitation. From the point of view of thermal insulation, it does not provide any effect. The top waterproofing barrier is roofing material or a special film that is capable of retaining water, but is vapor permeable. It is laid in such a way that water flows through it to the outside. Next comes a layer of insulation, which forms a thermal insulation barrier.
The vapor barrier is designed to completely protect the installed insulation layer from moisture and steam. This polyethylene film is truly completely vapor and waterproof. Everything ends with a decorative coating to give aesthetic appeal and protection from mechanical damage.
The greatest difficulty in insulating an attic space is installing a waterproofing layer on insulation of a complex shape. The difficulty lies in bypassing all the load-bearing elements of the roof and organizing its exit under the roof to discharge water. It is very important here to maintain the integrity of the layer. The joints and fastening points must be taped, and secured between the rafters with staples or vertically nailed slats.
The insulation is placed tightly between the rafters and, together with the hydrobarrier, is secured with slats, which will later serve as a support for the finishing. It is recommended to insulate with mineral wool formed into sheets or slabs, since it is more resistant to caking and shedding during operation compared to rolled wool.
Final finishing
The material for the final finishing of the attic can be any sheet material that can protect the insulation from damage. Most often, plasterboard, chipboard or OSB boards, as well as wooden lining or plastic are used.
Installation is carried out on slats that secure the thermal insulation to the roof. You can assemble a separate metal frame from profiles, but this will require additional space in the attic and will once again compromise the tightness of the waterproofing.
Properly installed attic insulation will not only help conserve heat, but will also protect roofing and ceiling elements from premature aging.
To understand why it is necessary to insulate the ceiling of a cold attic, let’s clarify a little why an attic is needed in a private house and what its purpose is. Our ancestors built houses that could stand for more than 100 years, while it was warm inside, and the wooden roof structure always remained dry.
Previously, gable roofs were mainly built with a slight slope of the slopes. This was done so that snow could remain on the roof in winter. Thus, snow was used as a natural insulation. One or two windows were made in the attic and kept closed in winter so that the trapped air acted as a heat insulator. In the summer, a slightly different situation occurred. Attic windows were opened at night so that the air cooled, and during the day, in hot weather, they were closed so that the air did not heat up too much, thus regulating its temperature.
When snow fell in winter, it fell as a continuous cover on the roof, simultaneously becoming a natural insulation. Even in severe frosts, the temperature in the attic did not drop below zero. Thus, the air in the attic and the insulation of the ceiling made it possible to maintain the temperature in the house at +20-25 °C. The roof slopes were not insulated to prevent the snow lying on the roof from melting. The rafter system remained open, allowing it to be inspected and repaired if necessary. Therefore, in a cold attic, only the ceiling is insulated.
If the roof slopes are insulated, then the attic becomes a heated room, i.e. an attic, which has a completely different functional purpose.
Now it remains to find out how to insulate the attic floor in a private house, and what materials are used for thermal insulation.
Materials for insulating attic floors
There is a wide range of insulation materials on the market. To make a choice, it is necessary to take into account the conditions in which the thermal insulation material will be used:
- The material must retain its properties at temperatures ranging from -30 to +30 °C. It should not freeze in severe frosts and should not emit harmful substances in hot weather.
- It is necessary to choose fire-resistant insulation if there is electrical wiring in the attic.
- It is better to choose a moisture-resistant material so that when wet it does not lose its thermal insulation properties.
- The insulation should not quickly cake in order to fulfill its purpose for as long as possible.
Before deciding on the type of material for insulating the floor of a cold attic in a private house, you need to consider what material the ceiling is made of. If the attic floor is made of wooden beams, then you can use slab, roll and bulk insulation. In the case where the attic floor is made of concrete slabs, they resort to the use of heavy bulk or dense slab heat insulators. Their use makes it possible to make a cement screed on the floor.
Materials produced in slab and mat formats:
- mineral wool (mineral wool) in mats;
- Styrofoam;
- extruded polystyrene foam;
- seaweed;
- straw.
Roll insulation:
- mineral wool;
- glass wool;
- stone wool;
- seaweed ladders;
Bulk materials for attic floor insulation:
- expanded clay;
- ecowool;
- reed;
- sawdust;
- straw;
- slag;
- buckwheat tyrsa;
- foam granules.
Insulation of the attic floor in a wooden house must be done with environmentally friendly, natural and breathable material.
How to properly insulate an attic floor with mineral wool
Mineral wool is a common and modern heat insulator. Available in rolls or slabs (mats). It does not rot or burn, rodents and various kinds of microorganisms are also not afraid of it.
Insulating the ceiling of a cold attic with mineral wool begins with laying lining material on the floor. For a budget option, glassine is laid on the floor, but a more expensive and high-quality option is flooring made from vapor barrier film. The film is laid with an overlap, and the joints are taped or secured with wooden slats, which are fixed with a construction stapler.
The width of the insulation is selected based on the requirements of thermal engineering standards for each region. Mineral wool is placed between the joists tightly and without gaps. The joints are taped with tape. After the insulation is laid, level boards are simply laid on the joists, thus forming the floor in the attic. This simple solution for creating a floor allows the mineral wool to “breathe” and ventilate normally if it gets wet. To prevent moisture from entering the mineral wool, waterproofing material is laid under the roof.
Mineral wool is laid using personal protective equipment: thick clothing, goggles, gloves, respirator.
Insulation of attic floor slabs with extruded polystyrene foam
Expanded polystyrene or polystyrene foam are not very dense materials, so they are used when the attic floor is a structure made of joists and beams. If thermal insulation of the slabs is necessary, insulation of the cold attic floor with extruded polystyrene foam is used. This material is stronger and therefore denser than regular foam. Before laying it, the surface of the slabs should be leveled. There is no need for vapor barrier on the warm side of the floor, since concrete slabs have almost no vapor permeability.
A vapor barrier film is laid on the leveled concrete slabs. Next, slabs of extruded polystyrene foam are laid in a checkerboard pattern. The joints are blown with polyurethane foam. After the foam has dried and hardened, the insulating slabs are poured with concrete mortar 4-6 cm thick. When the screed is dry, it is already suitable for use as a floor. Although you can go further and put any floor covering on the screed.
Thermal insulation of a cold attic with ecowool
Ecowool is a cellulose, lightweight and loose insulation material, consisting mainly of waste paper and newspapers. Other components - borax and boric acid - are used as flame retardants.
Before insulation, it is necessary to place a film on the floor. The procedure for laying ecowool occurs using a special blowing installation. The insulation layer is applied as a continuous cover, without creating cracks. Since ecowool contains a large amount of air, a layer of 250-300 mm is usually enough.
Do not forget that over time, the material will shrink. Therefore, apply a layer of ecowool 40-50 mm more.
After the insulation of the cold attic floor with ecowool is completed, it must be moistened. You can do this with plain water or prepare a solution of 200 grams. PVA glue on a bucket of water. Soak a regular broom in this solution and moisten the cotton well. After drying, a crust forms on the surface of the cotton wool - lingin, which will not allow the cotton wool to move.
As you can see, there are plenty of ways to insulate the floor in the attic. Which one to use depends on each specific situation. The main thing is to follow the correct technology for laying thermal insulation! Then your home will always be warm, and the materials used will last for many years.
Are you insulating your house for winter and don’t know how to insulate the attic floor using wooden load-bearing beams? Having gained experience in this matter, I will accurately convey the technical aspects of thermal insulation, and also describe step by step the procedure for carrying out the work.
Why insulate an attic?
We must not forget that a significant part of heat loss occurs through the roof. Therefore, when constructing buildings with cold attics, it is very important to pay attention to proper thermal insulation of the ceiling between the heated room and the attic.
Below I will try to explain in an accessible language how attic insulation affects the internal microclimate and overall heat loss in the house:
- Purpose of the attic. Any unused attic under a sloping roof is, in fact, a buffer technical floor between the street and the living space. Its purpose is to smooth out significant changes in air temperature inside the house and outside;
- Temperature conditions. At any time of the year, during the day the air temperature inside the attic will be several degrees higher than outside. Thus, in winter there will almost always be negative temperatures in the attic, and on sunny summer days there will be intense heat;
- Heat losses in winter. When the temperature of any substance increases, its density always decreases. Therefore, in heated rooms, heated air from household heating appliances always rises up to the ceiling. If the ceiling has insufficient thermal insulation, then during the cold season, all the heat from the room will go outside through the attic;
- Excess heat in summer. On hot summer days this process will occur in reverse. The air in the attic will become very hot from the hot roof in the sun, and then transfer its heat through the uninsulated ceiling into the apartment.
- Reverse air circulation. After touching an uninsulated ceiling, the heated air quickly cools down, and due to the increase in density, it sharply sinks down. Indoors, this leads to excessive reverse air circulation and the constant formation of drafts, which have an adverse effect on the health of residents;
- High humidity. When heated, humid air comes into contact with a cold, uninsulated ceiling, small drops of condensation may form under the ceiling. This will lead to an increase in air humidity in the house, and will also contribute to the appearance and development of mold on the walls and ceiling;
- Economic factor. Confirmed heat loss through an uninsulated roof is at least 20-30%. This means that proper insulation of attic floors using wooden beams will save up to 30% of fuel during each heating season. Air conditioning in summer will also require lower costs;
- Damage from a “warm” attic. Among other things, the penetration of warm air into an uninhabited attic, from time to time, can lead to unpleasant consequences:
- As warm and cold air mixes, condensation will begin to form in the attic. Drops of water will settle on all surfaces, which will lead to rotting and destruction of the wooden supporting structures of the roof;
- From the warmth of the attic, the snow masses on the roof slopes will gradually begin to melt. Thawed water will freeze as it flows down. This can lead to the formation of large icicles along the edges of the roof, as well as freezing of rain gutters and downspouts.
All the factors described are typical not only for residential buildings. They should be taken into account when designing and constructing any outbuildings on the site in which the heating system will be used (for example, a garage, bathhouse, barn, etc.).
Stage 1: Selecting insulation
When choosing materials for ceiling insulation, you should be guided by several criteria. In addition to low thermal conductivity, attic insulation must have the following qualities:
- Moisture resistance and mechanical strength. The material should not be deformed or destroyed under the influence of mechanical load, and should not change its properties in the event of direct contact with water;
- Heat resistance. The insulation must be absolutely non-flammable and should not be destroyed under the influence of high or low temperatures;
- Light weight. In order not to create additional load on the load-bearing structures of the building, the thermal insulation of the attic floor should be quite light, so you need to choose insulation with a low specific gravity;
- Vapor permeability. To ensure normal temperature and humidity conditions in residential premises, all finishing and building materials must freely allow air and water vapor to pass through;
- Environmental Safety. Insulation for residential buildings must be hypoallergenic and chemically neutral. It should not contain harmful volatile compounds or toxic substances;
- Lack of organic matter. I recommend using exclusively mineral or polymer based materials. They do not contain organic substances, therefore they are not susceptible to mold, and are not suitable for food for small rodents and pests.
Taking into account all these factors, several types of thermal insulation materials can be used to insulate attic floors:
- Mineral wool. Produced in the form of rolls or rigid mats, from intertwined frozen fibers of molten sedimentary rocks. Mineral basalt wool is characterized by all of the above qualities, so it can be considered the most suitable material. Below I will give some recommendations for its use:
- Basalt wool itself is very soft. To prevent it from being pressed or dented while walking, plank flooring should be laid on top of it in the attic;
- When choosing insulation, I advise you to give preference to rigid slabs that are covered on one side with aluminum foil;
- They need to be mounted with aluminum foil inside the room. It simultaneously reflects heat and acts as a vapor barrier layer.
- Glass wool. It has a similar manufacturing technology, only molten glass is used as the raw material for its production. I do not recommend using this material for insulating residential buildings for the following reasons:
- Glass fibers are more fragile, so they can break under load;
- The price of glass wool is much lower, but after creasing or getting wet, it partially loses its heat-insulating properties;
- Small particles of glass penetrate deeply into a person's skin and cause severe irritation.
- Expanded clay. This bulk insulation is produced in the form of small round pellets of light brown or red color. Expanded clay balls are formed as a result of sintering special varieties of red clay under high temperature conditions.
Expanded clay has the following characteristic qualities:
- The internal structure of the material has many closed pores, so it has low thermal conductivity;
- Each pellet is covered on the outside with a dense glassy layer of baked clay, so moisture practically does not penetrate inside it;
- Small crumbly expanded clay pellets freely fill the entire volume, so they are convenient to use for insulating hidden cavities and hard-to-reach places in building structures;
- Thanks to its mineral base, this material does not burn at all, does not emit harmful substances, is not susceptible to mold, and is not suitable for rodent food.
- Styrofoam. This polymer thermal insulation material is made by hot molding from small round granules of polystyrene foam. It is usually produced in sheets measuring 1000x1000 mm, which can be from 10 to 150 mm thick. The following features are characteristic of polystyrene foam:
- Of all existing types of insulation, it has the lowest thermal conductivity;
- The foam contains no organic substances, so it is absolutely not afraid of water, does not rot and does not contribute to the formation of mold;
- By itself, polystyrene foam does not burn and does not support combustion, however, when exposed to high temperatures, it can emit toxic gases and acrid thick smoke;
- Due to the polymer base and closed porous structure, foam sheets do not allow air and water vapor to pass through. For this reason, it is not very good to use for insulating living rooms and rooms with high air humidity.
- Extruded polystyrene foam Abbreviated as EPPS. It has the same composition as polystyrene foam, but is made by hot extrusion from a molten mass of polystyrene foam. The technical characteristics of these two materials are also very similar, however, EPS still has some differences:
- Expanded polystyrene has a porous, uniform structure and a higher specific density;
- Due to this, it has higher thermal conductivity, but at the same time is more durable, and therefore is able to bear higher weight loads;
- For this reason, I recommend using it for insulating unheated attics that will be used for storing seasonal items or household equipment.
- Foil polyethylene foam. It is also called “Penofol” in another way. This roll material consists of thick polyethylene foam film, which is covered on one or both sides with a thin layer of aluminum foil. I recommend using it in combination with other types of insulation, because by itself it has specific properties:
- The porous structure of polyethylene foam provides a low heat transfer coefficient, so it functions as an additional insulation;
- Polyethylene film does not allow air, drops of moisture and water vapor to pass through at all, so Penofol can be used as waterproofing;
- Mirror aluminum foil reflects infrared heat waves well. In other words, it does not allow radiant heat to pass through itself, and returns it back to the room.
- Wood sawdust. This cheap and accessible material is still often used to insulate ceilings in bathhouses, heated barns or small country houses. It is applied to the wooden floor from the attic side, in the form of a homogeneous thick mixture of sawdust with a liquid clay solution. Despite the seeming primitiveness of this method, it has its advantages and disadvantages:
- Sawdust or small shavings can be bought inexpensively, or even taken for free, at almost any large sawmill;
- There can be no problems with clay either, so such insulation is easy to prepare with your own hands in the required quantity at any time;
- The mixture of sawdust and clay has a low specific gravity, and after hardening it becomes quite hard. Therefore, it does not exert a significant load on the load-bearing beams, and allows you to walk on it with your feet;
- Due to the mineral components, such a coating is permeable to air and steam, however, due to sawdust, mold may form on it, or mice may chew on it.
All mineral-based thermal insulation materials, to one degree or another, are capable of allowing water vapor and air to pass through. To protect such insulation from the formation of condensation or moisture penetration from the outside, they must be installed using a vapor-permeable waterproof membrane.
Stage 2: Preparation of materials and tools
In addition to insulation, for the work you will need lumber, waterproofing, as well as the usual set of carpentry and carpentry tools:
- Two hammers: one medium, weighing 200-300 grams, and one heavy, weighing 800-1200 grams;
- Longitudinal and transverse hacksaw for wood. Instead of a cross saw, it is more convenient to use an electric cutting machine;
- A carpenter's plane, a large wooden mallet and a set of chisels;
- As for electric tools, you need to have an ordinary household drill, and it is advisable to have a cordless screwdriver with a set of replaceable attachments;
- To fasten rolled materials (waterproofing, vapor barrier), I recommend using a construction or furniture stapler with a set of metal staples;
- You will also need a straight metal ruler, a tape measure 3-5 meters long, a building level and a simple rope plumb line;
- To work near the ceiling, it is most convenient to use a folding stepladder. If you don’t have one, you can use a high, strong table or homemade trestle made from scrap boards for this purpose;
- From lumber you will need wooden blocks with a cross-section of 62x62 mm, and planed edged boards with a thickness of 25-30 mm;
- As a waterproofing layer, you can use a film of foamed polyethylene and a vapor-permeable waterproof membrane;
- To seal the joints of the panels, you will need metallized aluminum tape, which is usually used in ventilation systems;
- Each homeowner chooses materials for finishing the ceiling at his own discretion. This could be lining board, drywall, laminated OSB or plywood, or other finishing materials;
If you plan to use mineral or glass wool for insulation, then I recommend purchasing a special protective suit that is designed to work with these materials. Otherwise, severe irritation may occur on exposed areas of the skin from small glass fibers.
Stage 3: Filing the rough ceiling
When building an attic floor or erecting a sloping roof, you can do without expensive and heavy concrete floor slabs. Instead, the entire load from the roof is carried by wooden load-bearing beams made of logs or timber, with a cross-section of at least 120x120 mm. They are usually laid on top of two main exterior walls, perpendicular to the long side of the house.
Such beams serve as a supporting structure for the ceiling of the top floor and for the floor of the attic. The same beams will also be used for installing insulation between the residential building and the attic. This type of ceiling is called hemmed, because both the rough and the finished ceiling are hemmed from below to the load-bearing beams.
Before insulating the attic floor, you need to mount the rough ceiling:
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Installation of a rough ceiling. To hem the rough ceiling, you should use dry edged boards 25 mm thick, or plywood sheets 10 mm thick or more. |
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Hemming boards. They must be secured to the lower plane of the supporting beams and beams around the perimeter of the room. Hemming boards must be fastened without gaps or cracks, close to each other. For fastening, use galvanized self-tapping screws 5-6 mm. |
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Waterproofing. When the entire rough ceiling is hemmed to the load-bearing beams, panels of foiled polyethylene foam need to be secured to it from below. This can be done using a stapler. "Penofol" will perform the functions of heat and waterproofing. It should always be placed with a foil layer towards the warm room. |
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Sealing joints. To prevent moist air from the room from entering the insulation, the ends of the polyethylene film must be wrapped on the walls by 150-200 mm. The joints between the panels must be glued with metallized tape on an aluminum base. |
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Attaching the sheathing. From below, across the entire area of the rough ceiling, nail a counter lath made of wooden slats 15-22 mm thick. It is needed in order to provide a ventilation air gap between Penofol and the finished ceiling. The distance between the slats should be about 400-600 mm. In the future, a finishing ceiling covering will be attached to them from below. |
Before starting work, all wooden structural elements must be treated with antiseptic and fire-retardant impregnations. Antiseptics are needed to protect wood from rotting and mold development. Fire retardants give dry wood fire retardant properties.
Stage 4: Installation of thermal insulation
After filing the rough ceiling, the transverse load-bearing beams will be on the side of the attic. Insulation will be laid in between them.
Depending on the thermal insulation materials used, further installation technology may have some differences. Therefore, below I will briefly discuss the use of the most common types of insulation.
- Laying mineral wool. Mineral insulation materials, when wet, partially lose their properties. To prevent condensation from forming in the mineral wool, the entire thermal insulation layer of the cold attic floor must be permeable to air and water vapor:
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Vapor barrier. First, you need to lay a vapor-permeable waterproofing membrane on top of the rough ceiling. Its peculiarity is that it freely allows water vapor molecules to pass through, but does not allow bound liquid water molecules to pass through. The membrane panels must overlap each other by at least 150 mm; |
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Installation of insulation. Place sheets or rolls of mineral wool in the spaces between the wooden beams. If it is very soft, then it does not need to be squeezed or squeezed much. Lay another layer of vapor-permeable membrane on top of the mineral wool. To prevent it from moving over time, it must be stapled to the beams and walls, throughout the entire area and along the perimeter of the attic. |
- Installation of foam plastic. Polymer-based insulation does not have breathable properties, so it does not allow air and moisture to pass through. There is no point in using a waterproof membrane in this case:
| Illustration | Description of work |
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Laying foam. Foam or extruded polystyrene panels can be laid between the cross beams, directly on top of the sub-ceiling boards. I advise laying them in two layers, so that the joints of the sheets are located in different places and do not intersect with each other. |
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Polyurethane foam. To prevent the insulation sheets from moving to the sides, they can be glued to the sub-ceiling using a special glue for polystyrene foam or polyurethane foam. Thus, it is necessary to fill the entire area of the attic floor with insulation. If there are gaps and cracks between the sheets of foam plastic, then they must also be blown out from a balloon with polyurethane foam. |
- Clay with wood shavings. Insulating the attic floor with a sawdust-clay mixture does not require any additional materials, and is also quite simple:
| Illustration | Description of work |
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Preparation of the solution. To make the sawdust-clay solution plastic, the clay must be soaked in water 2-3 days before starting work. To prepare the solution, you need to take 3-4 volume parts of sawdust, and 1-2 parts of dry red clay without large solid particles and foreign impurities. Mix the soaked clay with water until a liquid, flowing solution is obtained; Add sawdust to the resulting mixture and mix thoroughly until smooth. To protect against mold formation, a small amount of copper sulfate can be added to the prepared solution. |
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Laying sawdust-clay mixture. Lightly moisten the supporting beams and boards of the rough ceiling with liquid clay milk. After this, fill all the gaps between the beams with sawdust-clay mortar and leave for several days until completely dry. |
- Expanded clay backfill. I want to say right away that expanded clay does not have very good heat-insulating properties, therefore, in individual construction, such insulation of floors is rarely used. At the same time, it is considered inexpensive, unpretentious and the easiest to install:
| Illustration | Description of work |
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Preparatory work. Expanded clay pellets do not absorb moisture, and therefore are not afraid of water ingress or condensation. Therefore, they can be used both with and without a waterproof membrane. To prevent condensation from seeping through the ceiling into the house, I still recommend laying a waterproofing membrane under the pellets; |
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Filling of pellets. Expanded clay pellets should be poured on top of the rough ceiling boards and evenly distributed in a thick layer over the entire area of the attic. No covering material is required on top of expanded clay. |
To prevent expanded clay pellets from bunching up and spreading throughout the attic, a retaining plastic geogrid is used. It needs to be stretched in the spaces between the load-bearing beams, and then expanded clay should be poured into its cells.
Stage 5: Arrangement of the floor in the attic
Many residents use the cold attic in their private home as a storage room for storing long items, seasonal items and all sorts of unnecessary rubbish. In order for a person to safely walk on the insulated floor, the attic must be equipped with a durable subfloor.
The choice of material for installing the floor in the attic will depend on the type of insulation used:
| Illustration | Features of application |
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Mineral wool and polystyrene foam. These materials themselves are very soft. To prevent them from being destroyed or wrinkled while walking, the top floor covering must be sufficiently rigid. In such cases, OSB or plywood sheets with a thickness of at least 18 mm should be laid on the load-bearing beams. You can also use unplaned edged boards with a thickness of 25 or 30 mm. |
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Extruded polystyrene. It has higher rigidity, so it can withstand significant loads. To prevent it from being pressed when walking, it is enough to put a light flooring of thin boards or plywood 5-9 mm thick on top of it. |
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Under the weight of a person, they will crawl in different directions. To prevent this from happening, you need to lay 10 mm thick plywood sheets or light wooden ladders made of boards on top of the beam floor. |
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Sawdust-clay insulation. After the solution hardens, it becomes hard like cement. A person can move freely on its surface, even without installing additional flooring. |
When installing rough flooring in the attic, you should always leave gaps 15-20 mm wide between boards or sheets of plywood. This is done so that moisture and condensation can freely evaporate from the insulation.
Conclusion
Using this operating algorithm, you can easily insulate the attic floor in your own home. More visual information on each method of insulation can be viewed in the attached video in this article, and I suggest leaving all your comments and questions in the comment form.
August 27, 2016Specialization: Capital construction work (laying a foundation, erecting walls, constructing a roof, etc.). Internal construction work (laying internal communications, rough and fine finishing). Hobbies: mobile communications, high technology, computer equipment, programming.
If you live in an apartment building, then you have hardly ever thought about insulating the attic. Moreover, you would hardly have guessed that there was such a technical room in the building, unless, of course, you ran to the roof as a child.
However, in a village house or country cottage (which I am currently building for my son), the roof space plays a huge role. Often an open expansion tank of the heating system, ventilation pipes, and chimneys are installed there. And sometimes they equip living quarters - attics.
Therefore, I will not talk for a long time about how important thermal insulation measures are for this room, but will simply tell you how to insulate the attic of a private house using the example of my own son’s country house.
I think the technology described will be useful to everyone who is building or is planning to build a home outside the city with their own hands.
Materials for thermal insulation
Attics have been insulated for as long as I can remember. My great-grandfather and grandfather used hay and straw, sawdust and shavings for this purpose, and some in their village used dry leaves from trees.
Dad was already a more “advanced” builder and cold - in a private house and at the dacha he insulated the attic with expanded clay and old soldier’s blankets. By the way, expanded clay granules are also used in modern construction.
Now I will not tell you which option is better from the above, since I can offer more technologically advanced and effective thermal insulation materials for insulating the attic.
However, before this, I will note what technical characteristics must be inherent in the heat insulator so that it can be used for the described work:
- Light weight. The material after installation should not place a large load on the attic floor, roof trusses and load-bearing walls.
Otherwise, more durable building materials will have to be included in the project during construction, which increases the amount of the final estimate.
- Safety. The material used for insulation should not cause harm to human health.
Therefore, both the floor of a cold attic and the roof must be insulated with heat insulators that do not release hazardous chemical compounds into the air. Especially if you plan to arrange a living room there in the future.
- Easy to install. The less effort you need to spend on installing thermal insulators, the better, right?
In addition, there is not much space in the under-roof space of some houses, so it is not very convenient to work there. I always try to buy materials that do not require the use of complex equipment when laying them.
- Low thermal conductivity coefficient. The better this indicator is, the smaller the layer of thermal insulation material should be used. Accordingly, the internal space of the attic will not be reduced much.
Again, I think this is important, since I plan to make an attic in the attic at my son’s dacha. But I think you are not very interested in laying thermal insulation 20-30 cm thick.
- Hydrophobic properties. In attics, the air often has high humidity, which reduces the efficiency of the heat-insulating layer.
I advise you to choose materials that are either treated with water-repellent compounds, or those that do not change their technical characteristics as a result of getting wet.
- Fire safety. The roof is where there is a risk of fire due to improper installation or a clogged chimney pipe.
Therefore, when choosing a material, I would give preference to those varieties that do not ignite under the influence of open fire and do not support combustion.
Of course, I was unable to choose the ideal insulation that 100% meets all the listed requirements. But I’ll still tell you about those with whom I had to work.
So, I insulated the attics:
- polyurethane foam;
- polystyrene foam;
- mineral wool;
- expanded clay.
I'll tell you about them in more detail.
Polyurethane foam
The raw material for the manufacture of this heat insulator is plastic. Insulating an attic with polyurethane foam is a pleasure, but this requires special equipment. The fact is that the insulator is applied by spraying, for which compressors are used.
But you don’t need to buy screws, adhesive mixtures, lathing, and so on. And the polyurethane foam itself is applied very tightly, leaving no gaps through which cold air can penetrate into the under-roof space.
After hardening, the insulation becomes rigid, therefore it further strengthens the structure. The material has antiseptic properties; mold, mildew and other microorganisms do not multiply on its surface.
If you need to insulate a ventilation pipe in the attic, you can also use polyurethane foam. Just not sprayed, but in the form of ready-made shells with a protective layer of aluminum foil. They simply need to be secured to the pipelines using adhesive tape or plastic ties.
The biggest disadvantage of the material in question is its high price. However, if you consider the total cost of the work, you can save money, because additional hydro- and vapor barrier is not required in this case.
Styrofoam
This insulation, as well as polystyrene foam, which is similar in technical characteristics, is widely used for insulating rooms under the roof. I personally prefer polystyrene foam produced by extrusion. It is more durable, does not burn, has a low thermal conductivity coefficient and is not damaged by rodents.
The cost of insulation is quite affordable, and anyone, even the most inexperienced summer resident, can install it in the attic. Polystyrene is processed with hand construction tools and secured with dowels.
Mineral wool
Fibrous heat insulators are a universal material. Mineral fiber-based insulation comes in rolls, slabs, in the form of a dry mixture, and so on. They are perfect for insulating attic floors and roofs.
The basalt fiber from which mineral wool is made has a very high melting point. Therefore, this insulation can be used for installation on chimneys, the surface of which can become very hot.
There is one point here. The insulation is not waterproof and can lose its heat-protective properties when wet. To avoid this, when insulating, it is necessary to install hydro- and vapor barrier membranes. Or buy those varieties of mineral wool that are treated with special water-repellent compounds.
The bottleneck of some types of mineral insulation is environmental friendliness. In the manufacture of basalt mats, a certain amount of formaldehyde resins is used, which can be harmful to human health. Especially during the installation process.
Expanded clay
Granules of this material, as I already told you, were used by my father when insulating his first dacha. Expanded clay has a low thermal conductivity coefficient and weighs little. However, it is free-flowing, so it can only be used to insulate the floor of the roof space.
But the installation process itself does not require any tricks. You just need to pour it on the floor, and then protect it well from moisture with a moisture-proof membrane. If you are going to later equip the attic, you can cover it with a screed on top, and then lay a decorative covering.
Do-it-yourself insulation of the attic space
We’ve sort of decided on the most popular thermal insulation materials, now I’ll tell you how to properly insulate the under-roof space so that you can build an attic there in the future.
Let's deal with the question of how to lay insulation under the sheathing, because this method will allow you to stuff your chosen decorative material on top without any problems.
In my son’s attic, I decided to use mineral wool, but I’ll tell you right away about polystyrene foam, since the working technologies are similar, and foam plastic is easier to work with if you are a novice builder.
The entire insulation process consists of several stages:
- Preparation;
- waterproofing;
- laying the heat insulator;
- vapor barrier;
- arrangement of sheathing and installation of decorative cladding;
- insulation of utilities;
- floor insulation.
I'll tell you about each stage in more detail.
Preparatory activities
Let's start, as usual, with preparation, because it is unlikely that your attic is already ready for construction work.
After all, in almost 100% of cases this room is used as a trash storage facility, where all unnecessary things are demolished (and sometimes taken from the apartment). The attic of my son’s dacha was clean, since the house was new, but in my home, while clearing out the rubble, I found old books, clothes, several family heirlooms (which my wife did not consider such) and much more.
In addition, if you have tried to insulate before, I advise you to get rid of all traces of this process. For example, remove sawdust, scraps of felt, construction debris, and so on from all crevices. Believe me, I have insulated attics more than once and I know how important it is.
By the way. And drive away all the spiders from the attic, and then clear the room of cobwebs. After all, you will be building an attic for yourself or your children, and not for any insects.
Last moment. Bring the necessary tools into the attic and provide lighting. It’s unlikely that you have sockets there, so you’ll have to run an extension cord with a light bulb. Although these measures seem obvious to you, since I had to return to the city for an electric one, since not a single extension cord at the construction site reached from the distribution panel to the attic.
Waterproofing
A waterproofing membrane is needed in order to protect the thermal insulation layer itself and the room under the roof from excess moisture. This is especially important if the roof was laid a long time ago (for example, you are insulating the attic of an old house) and the roofing materials used are not the most modern.
The moisture-proof film is installed directly on the rafter structure. It needs to be stretched and overlapped so that after finishing work a sealed layer is formed. You can fasten the material with a construction stapler with staples.
Laying insulation
Thermal insulation material, as I already said, must be mounted on a pre-assembled sheathing. However, if you want to save a little money, there is no need to construct a separate frame. Its role will be perfectly played by the roof rafter system.
In the latter case, in order to press the material and be able to install decorative sheathing, you will only need to install a light counter-lattice at some distance from the surface of the heat insulator. Then you will get a small ventilation gap that removes excess moisture from the insulating layer.
So, the scheme of work for laying insulation is as follows:
- Mineral wool rolls must be cut so that their width matches the distance between the rafter supports. After this, lay it under the roof surface, gluing it to the surface or temporarily securing it with wooden slats.
- To make installation easier, you can use mineral mats. Their width should be slightly greater than the distance between the rafters, so that after installation they will snap into place and not fall out.
- The foam must be cut as accurately as possible so that it fits closely to the installation site. The gaps between the insulation panels will greatly reduce the effectiveness of insulation measures, so they need to be filled with foam.
Vapor barrier
After laying the insulation, you need to install a vapor barrier membrane. It will protect the insulating material from penetration of moisture generated during human activity.
For vapor barrier, special films are used that prevent the heat insulator from getting wet, but do not prevent air infiltration through the enclosing structures. As a result, a microclimate that is comfortable for living will be formed in the attic, if you look at it from the point of view of humidity.
So, after installing the insulation, it is necessary to attach a vapor barrier to the rafter supports (which act as sheathing). This should be done using a stapler, carefully pulling the film.
The edges of the material overlap each other to prevent the mineral wool from getting wet. To further insure yourself against surprises, I recommend sealing the seams with adhesive tape.
Vapor barrier films allow air to pass in only one direction. Therefore, before installation, make sure that you have turned the membrane to the desired surface.
Counter-lattice
Having finished with the films, you can begin to complete the finishing operations of the walls (or the roof, depending on how you look at it). I will use for this, but in the same way you can fasten OSB boards, drywall, lining, and so on.
Here, too, there is an opportunity to significantly save on the purchase of materials and reduce the time for carrying out all work. The fact is that the main parts of the sheathing will be powerful rafter legs, and all you have to do is make cross members that will serve as additional stiffeners for the sheathing.
The material for the transverse frame can be a wooden strip or galvanized profile. The essence will not change. The parts just need to be screwed from above to the rafters so that they are located at right angles to them. The step between adjacent elements depends on the decorative finish; I made it 30 cm so that the cladding does not sag under load.
The decorative finish itself also depends only on your imagination. I'm going to glue the wallpaper on top for now to save money, and then I'll come up with something more beautiful. You can do the same.
Just before gluing the wallpaper, do not forget to putty the seams between the sheets of plywood and perform other necessary operations (primer, etc.).
Insulation of utilities
If you do not plan to create an attic, you definitely need to insulate the ventilation ducts in the cold attic, as well as, if there are heating, water supply and smoke exhaust pipes (the term you came up with).
Of course, you can use mineral wool for this, wrapping it around the pipes, wrapping it with roofing felt and securing it with wire. But why complicate your life if you can buy ready-made shells for pipes of the required diameter (made of polyethylene foam, polyurethane foam, polystyrene foam, and so on). They just need to be snapped onto the pipe and secured with tape to be sure.
The cost of such insulators is low, so you definitely won’t go broke.
Insulation of the attic floor
The floor is a horizontal surface, so it can be easily insulated with bulk material. For example, expanded clay. But since I started working with mineral wool (foam plastic), I won’t buy expanded clay, I’ll limit myself to what I have at my disposal.
So, the attic insulation technology is as follows:
- First you need to clean the surface of dust, accumulated debris, foreign objects, and so on.
- Then install the support joists. I make them from wooden blocks with a section of 20 by 10 cm. You can select the height of the logs based on the thickness of the thermal insulation material you have.
- The entire surface is covered with a layer of waterproofing. Be sure to ensure the tightness so that the mineral wool does not get wet, as this may affect its technical characteristics.
- Cotton wool is placed on the waterproofing layer. Choose a material that is specifically designed for insulating horizontal surfaces. For example, Izover KT37.
- The vapor barrier membrane is again stretched on top, onto which the facing material is stuffed. I used plywood, which I plan to cover with linoleum.
If you do not plan to use the attic as a living space, then you can not insulate the roof, but only insulate the floor. In this case, you need to pay attention to some features:
- Wood for joists and cladding must be treated with hydrophobic, fire-retardant and antiseptic compounds to maximize its service life.
- For entry, it is better to use an insulated hatch to the attic, since it is this structural element that is often the source of large heat losses.
Now we can say with confidence that the insulation of the floor (or ceiling from the cold attic side) has been completed in full. And in order to achieve maximum efficiency of thermal insulation measures, I still advise making an insulated hatch with a ladder, as described in the video in this article.
Conclusion
As you can see, there is nothing scary or difficult here. If you liked the material or have any questions, you can ask them in the comments. I would also be grateful for stories about how you insulate the attic in a private house with your own hands.
August 27, 2016If you want to express gratitude, add a clarification or objection, or ask the author something - add a comment or say thank you!