The charm and benefits of the attic space will come to naught if the walls freeze and become covered with black fungus. In addition to the interior decoration, insulation of this room is one of the main tasks. What insulation is better for the attic? To make the right choice, you need to carefully understand its types and properties.
Based on the stage at which thermal insulation is planned, there are two ways to insulate an attic. The external method is considered the most optimal. and roofing is often carried out immediately, during the construction and cladding of the house. External insulation helps save internal space. Not suitable for insulating frame buildings.
Internal insulation is carried out both in addition to external insulation (rarely), and when, for some reason, external insulation cannot be performed. Regardless of which insulation method is chosen, it is worth considering:
- purpose of the attic space. You need to decide how often and during what period of the year you plan to use this territory;
- climatic conditions of the region. The insulation material must meet all requirements. It is important to take into account such phenomena as severe frost, sudden temperature changes, high humidity;
- attic design - number of windows, roof slope, wall thickness, etc. All these factors will help determine the level of insulation, its thickness and strength.
It is best to entrust external thermal insulation to professionals who are well aware of all the intricacies of their work. And here internal works you can do it yourself. Therefore, we will take a closer look at the second method. Most often it occurs in a circular pattern - roof, facades, floor. Insulation of one thing is less common. Today we have a huge selection of insulation for the attic - for every budget. We hope that our article will help you decide what is the best way to insulate your attic.
You need to approach the purchase of materials with feeling, sense, and arrangement. Having decided on the manufacturer and seller, before finally choosing insulation for the attic, it would be a good idea to familiarize yourself with the certificates of conformity. Remember that the further success of the event depends on the quality of the purchased insulation.
To clearly understand what material to insulate the attic with, you should take into account such characteristics as:
- Thermal conductivity of the material;
- Moisture resistance;
- Resistance to temperature changes;
- Durability;
- Fire safety. The material must contain substances that slow down the spread of fire (fire retardants);
- Environmental Safety.
Particular attention should be paid to the density of the material. Its structure must be strong and light at the same time. High-quality insulation should not change shape when used. The presence of defects and cracks indicates poor quality material. Using this in the future will lead to the need to redo all the work.
Let's look at the most common materials for attic insulation. Let's note the advantages and possible disadvantages of each. When choosing, it is important to navigate the diversity and take into account absolutely all the nuances.
It would seem, what other insulation is needed for the attic? But there are also more modern materials. They are much easier to use, are strong and durable, and perform their function as efficiently as possible. In addition, you do not need to purchase them Additional materials. These are the so-called liquid and bulk insulation materials.
Insulation for an attic roof: how to choose and which one is better Why do you need to insulate the attic?
Before examining in detail how to insulate an attic from the inside, it makes sense to consider the structural features of the pitched roof covering. It is a multilayer system consisting of the following elements:
- vapor barrier;
- insulation;
- ventilation-air gap;
- waterproofing;
- external roof.
Some homeowners, trying to save on material, exclude one of the layers, but this mistake can be costly later. The fact is that, according to the laws of physics, heat always rises, and if the roof is poorly insulated, it will leak out onto the street, which will cause the cost of heating the house to be significantly higher.
It is quite simple to identify a poorly insulated attic in winter: if at subzero temperatures the snow does not lie on the roof, but melts, this means that heated air penetrates through the roof layer.
It is worth saying that the negative consequences of insufficient insulation of the attic will be felt not only in winter, but also in summer: the summer sun heats the roofing to high temperatures, and heat penetrates into the room.
Which insulation for attic roof is better?
On the construction market there is a huge amount of thermal insulation materials with similar properties that can be used to insulate the attic.
Criterias of choice
When choosing insulation for an attic roof, you should pay attention to several main factors:
- coefficient of thermal conductivity;
- fire resistance;
- moisture resistance;
- environmental friendliness of the material.
The thermal conductivity coefficient is the main criterion for a heat-insulating material, which should be taken into account when deciding how to insulate an attic roof. This coefficient reflects the ability of the material to release heat to the outside or transmit it from the outside. The lower the value of the thermal conductivity coefficient for a heat insulator, the better its thermal insulation properties.
Fire resistance is the ability of a heat insulator to withstand high temperatures (fire). In contrast to the thermal conductivity coefficient, the quality of the thermal insulation material is better at maximum fire resistance values.
Moisture resistance is an indicator that reflects the ability of a material not to transmit or absorb moisture. Living in a house will be comfortable only if the heat insulator does not emit carcinogenic substances. There are heat insulators that are made from natural materials; they are distinguished by the best environmental friendliness. All these indicators should be taken into account before insulating the attic from the inside.
Which insulation is best for the attic?
Taking into account the characteristics described above, you can begin to select the type of insulation, and then the manufacturer. Let's consider the most popular insulation for attic roofs, these include:
- mineral wool;
- linen or cotton fabric insulation (a modern analogue of glass wool, has a fibrous structure, breathable, environmentally friendly);
- glass wool;
- extruded polystyrene foam.
Mineral wool
From this list best characteristics Mineral wool is different: this porous heat insulator is made from mineral raw materials, which means it is highly environmentally friendly. In addition, this material is easy to work with, and with its help you can insulate the attic yourself. One of the disadvantages is the need for careful waterproofing, since the material absorbs moisture and is susceptible to rotting.
Mineral wool is fire resistant, and the thermal conductivity coefficient is in the range of 0.35-0.47. Insulating the attic from the inside with mineral wool allows for good heat conservation and good sound insulation.
Glass wool
It has the same properties as mineral wool, but is more durable. However, it has a low fire resistance coefficient and is quite toxic when burned. Its cost is lower than other thermal insulation materials, so it is used quite often for insulating technical premises.
Mineral and glass wool are also very different attractive price, therefore, insulating the attic from the inside with these materials will not require significant investment.
Extruded polystyrene foam
Durable heat insulator, made in the form of plates with a porous structure. Repels moisture without absorbing or letting it pass through, therefore it is often used as external (facade) insulation load-bearing walls buildings and attics, with a broken roof structure. Significant disadvantages This heat insulator is highly flammable, releases toxins during combustion and oxidation from heat, and is airtight.
Environmentally friendly and natural materials
Modern solutions aimed at maintaining health and environment, contain a minimum chemical fibers and are non-toxic when burned. Such building materials include domestic and foreign new products for insulation, such as:
- Ecolen;
- Ecowool;
- Cotton fabric insulation.
The main differences between these materials are that they allow air to pass through, while providing high-quality heat and sound insulation. They are hypoallergenic and filter odors well. In addition, laying such insulation for an attic roof is much easier, since Ekolen and other fabric insulation do not emit toxic substances and practically do not disintegrate into fibers, you will not need PPE OD (products personal protection respiratory organs) during work.
When laying ecowool through a sprayer, you must first cover the surface of the attic with film, leaving a hole that can be insulated later. It is also recommended to cover the floor and walls, especially if the room has already been used as a living space and will not be used for production. major renovation.
Do-it-yourself insulation of an attic roof from the inside video
Insulation of the attic roof: installation stages
So, the thermal insulation material has been selected, now you can insulate the attic roof from the inside. This work consists of several stages:
- preparing a site for installing insulation;
- installation of material;
- fastening the heat insulator.
The insulation is laid in a cellular structure in the space between the rafters, so the width of the insulation mats must correspond to the pitch of the rafters. The heat insulation is laid from the lower edge of the roof arch, while the heat insulation mats are laid overlapping. This technology allows us to minimize heat loss and reduce material waste.
With sudden changes in temperature outside the roof and inside the room, condensation occurs. To remove this moisture, you need to take care of the design of the ventilated space. This space is created by screwing the insulation onto self-tapping screws to the rafters of a wooden counter batten, the height of which will create the ventilation space.
To ensure the highest possible thermal insulation, it is necessary to exclude any cold bridges, so another thinner, continuous layer of material is laid on top of the rafters. The only drawback this method- the fact that visually the rafters become hidden, and subsequently the installation of new ones to them structural elements(most often facing) becomes difficult. The way out of the situation will be to mark the location of the rafters with a marker. If problems arise at any stage of the project, the video will help you sort out controversial issues and perform insulation as efficiently as possible.
A vapor-proof film, which is attached over the insulation, will help protect the structure from moisture coming from the room. The next step is to secure the structure using lathing. At the final stage, reflective thermal insulation is applied, on top of which finishing can be carried out.
Do-it-yourself attic roof insulation video
Finishing the ceiling in the attic
Finishing the ceiling in the attic is not only aesthetic, but also practical significance. Finishing the ceiling with fiberboard or plywood is one of the simplest and most inexpensive finishing options. In addition, these materials have a thermal conductivity coefficient of 0.2. This means that the ceiling will become an additional barrier to the cold.
The French came up with the idea of using the attic as a living space; they made it not just a room, but a place of relaxation. Achieve the same effect in own home you can use a stretch ceiling, which will help hide structural elements attic space and will give it greater attractiveness. In addition, a suspended ceiling can be very practical.
The fact is that no matter how well you insulate the attic, the sound insulation of this room will still be much inferior to the main rooms (the thickness of the roof is significantly inferior to the thickness of the walls of the house). Therefore, in rain or hail, the attic can be a little noisy. A suspended ceiling will help reduce this disadvantage.
Bottom line
Using these instructions, you can ensure that the once unattractive attic can be confidently called the French word attic. Not only will this room not be inferior to all other rooms, on the contrary, at any time of the year and in any weather there will be a desire to be here.
If the roof country house forms a spacious attic space, it can be used to expand the living space. The attic room can serve as a bedroom or office, a sports room, a cinema or a billiard room. To use extra bed all year round, needed good thermal insulation. Insulating the attic will not require large material costs, especially since the work can be done with your own hands. It is only important to choose the right one thermal insulation material and carry out the installation correctly.
Requirements for thermal insulation materials
The same technology that is used in the construction of frame houses is suitable for insulating the attic, however, increased demands are placed on the materials and quality of work. How well the thermal insulation will be done attic space, affects both the conditions of comfortable living and the durability of the roof. This is due to the fact that the walls of the attic room form the gables and roof slopes - those surfaces that heat up the most in the summer heat. In winter, on the contrary, blown by cold air currents, they cool down the fastest. If the thermal insulation is of poor quality, the roof will let heat out. One should not think that the danger of such a situation lies in a banal increase in energy costs for heating the attic. Warm slopes will provoke snow melting, and this is fraught with many more serious troubles - from mechanical damage to the top covering by the resulting ice to the appearance of fungi and mold that destroy the roofing pie and wooden structures of the rafter system.
High-quality thermal insulation will make the attic comfortable to live in both the summer heat and winter cold.
When choosing a material for insulating an attic, you should remember that not only the thickness and number of layers of thermal insulation, but also the ease of installation depends on this. Based on the specifics of using insulation, the following requirements are imposed on them:
- Ability to withstand peak temperatures. The material must be frost-resistant and not destroyed when high temperature, maintaining its characteristics even after numerous cycles of freezing-thawing or heating-cooling.
- Durability. The service life of thermal insulation should be no lower, or even higher, than other materials used on the roof. This is due to the fact that replacing a roofing pie is much more difficult than, for example, a top covering made of metal tiles or ondulin.
- The lowest possible thermal conductivity coefficient. It is best to take insulation with a value of no more than 0.05 W/m×K.
- Maximum moisture resistance. Since condensation may appear in the under-roof space, the material should not absorb moisture and lose its properties when wet.
- Fire safety. Thermal insulation must not burn or support combustion.
- Light weight. The insulation should be light so as not to create an increased load on the roof rafter system. Total weight thermal insulation can be determined by multiplying its density by volume. Experts recommend using materials with a density of up to 50 kg/m3.
- Ability to maintain a given configuration. The insulation is laid in the spaces between the rafters in an inclined position. If you choose a material that can deform under its own weight, then over time it can slide down, forming voids inside the structure. It is necessary to choose thermal insulation that can long time maintain original size and shape.
The type of thermal insulation chosen affects the thickness of the roofing pie. Later we will look at how to calculate the amount of material needed.
What materials are suitable for attic insulation?
You can make your attic suitable for living at any time of the year using various insulation materials. Let's look at their features and highlight their strengths and weaknesses.
Mineral wool
To insulate the attic space, you can use glass wool, mineral wool or slag wool. These materials have the following thermophysical and operational parameters:
- high thermal resistance - up to 1.19 W/(m 2 /K);
- low thermal conductivity - no more than 0.042 W/m×K;
- light weight - from 15 to 38 kg per 1 m2.
Cotton-type thermal insulation is a favorite option for home craftsmen if the roofing pie needs to be installed from the inside of the room. It does not support combustion and has minimum weight, and, importantly, rodents do not grow in its layer. The slab samples retain their shape perfectly, and when laying fiber insulation in the space between the rafters, no precise adjustment is required - the mineral wool is easily distributed without seams or gaps.
Mineral wool is produced in the form of roll and slab materials
The only drawback can be considered increased hygroscopicity. Due to the appearance of moisture between the fibers, the thermal insulation properties of the material drop by more than half, and the material itself begins to collapse. Therefore, mineral wool requires high-quality waterproofing from the roof side and installation of a vapor barrier membrane from inside the attic space.
Polymer thermal insulation
To insulate roof structures, polymer materials are often used - polystyrene foam and polyurethane foam. They retain heat well and, due to their hydrophobicity, are not at all afraid of moisture.
Plain polystyrene foam, also known as polystyrene foam, is one of the most popular insulation materials on the market. building materials. Good performance characteristics- minimal density, low thermal conductivity, moisture resistance and the ability to hold a given shape contribute to the idealization of this material. As a result, it is often used in places where it is strictly not recommended. Firstly, only non-flammable foam plastic of the G1-G2 brand is suitable for insulating residential premises, and not the popular G3-G4, which ignites perfectly and burns out in a matter of minutes. If you choose the latter for insulating the attic, then surviving a fire in it will be unrealistic. Secondly, installing ordinary polystyrene foam is not an easy task, since it is difficult to cut and crumbles easily. Thirdly, this material is subject to aging and begins to quickly deteriorate over time. And in conclusion, it should be noted that polystyrene foam is a favorite material among rats and mice, so it is used only where it will be covered with a layer concrete screed or hidden behind plaster.
Polystyrene foam is a type of gas-filled plastic that can be used to insulate an attic space.
Extruded polystyrene foam (EPS) is almost completely devoid of the disadvantages of polystyrene foam, which is well suited for thermal insulation of an attic room from the outside. To do this, insulation boards are laid directly under roofing material, on top of the rafter system elements. Extruded polystyrene foam contains fire retardants, so it burns poorly. Compared to foam plastic, EPS has higher strength and rigidity, which makes it much easier to install. Like other polymer materials, extruded polystyrene foam is waterproof, does not allow steam to pass through, and has good energy-saving properties. This makes it the best option for thermal insulation mansard roof outside. By the way, very little EPS is required - a 100-mm layer will be enough to insulate an attic space in most regions of our country.
Extruded polystyrene foam is best suited for external roof insulation
Polyurethane foam
Polyurethane foam (PPU) is a gas-filled plastic that is applied in liquid form to inner surface stingrays When set, the material forms a rigid foam with excellent physical characteristics:
- heat transfer - up to 0.027 W/m×K;
- thermal resistance from 1.85 to 9.25 W/(m 2 /K);
- thermal insulation density - from 30 to 86 kg/m 3 ;
- weight - from 11 to 22 kg.
To apply polyurethane foam, a special installation is used in which the liquid mixture foams when air or CO 2 is supplied.
To insulate a roof with polyurethane foam, you will have to turn to specialists - without special equipment and skills are indispensable here
This method of installation largely determines the advantages of the insulation, since when the under-roof space is blown out, there are no cracks, gaps or cold bridges left in the form of open elements of the rafter system. Polyurethane foam does not support combustion and does not change shape. It does not collapse over time and resists moisture well. By the way, the last factor causes low vapor permeability - the insulation does not allow the roof to “breathe,” which can lead to increased humidity in the attic space.
To ensure that the air in the attic space is fresh and light, and the wall surfaces are not covered with mold and mildew, when insulating the roof with polyurethane foam, you should definitely consider a high-quality supply ventilation system.
Ecowool can be considered one of the best materials for thermal insulation work at home. This insulation consists of more than 80% cellulose fibers, so it has low thermal conductivity and is well suited for filling gaps between rafters. Since cellulose in its pure form burns well and is destroyed by fungi, borax is added to its composition as a fire retardant and boric acid to protect against damage by biological organisms, including rodents.
Basic physical properties of ecowool:
- thermal conductivity - from 0.037 to 0.042 W/m×K;
- density depends on the degree of laying and varies from 26–95 kg/m3;
- flammability - group G2 according to GOST 30244;
- vapor permeability - up to 03 mg/mchPa.
In terms of its performance properties, ecowool is close to mineral and polymer thermal insulation, surpassing them in many factors. So, unlike mineral wool, it absorbs moisture without significantly reducing thermal conductivity. With an increase in humidity by 1%, a basalt slab will lose a tenth of its thermal insulation properties, while ecowool, when saturated with moisture to 25%, will increase thermal conductivity by no more than 5%.
Ecowool in the form of slabs of various thicknesses is suitable for insulating the attic.
It is also important that when the cellulose insulation dries, it completely restores its original characteristics. At the same time, it can serve as a kind of buffer, capable of maintaining a comfortable level of humidity in the room. Ecowool allows for seamless installation, therefore it forms a monolithic layer without gaps or cold bridges. Its breathability is almost two times lower than that of mineral insulation, and at the same time it remains elastic enough to dampen sound waves. When using ecowool, the attic will be best protected from external noise. And finally, it is impossible to remain silent about the environmental friendliness and safety of this material. It does not contain a single chemical compound that could evaporate and release substances harmful to humans.
How to calculate the thickness of thermal insulation
To calculate what layer of insulation will be needed to insulate the attic, builders use the formula from SNiP II-3–79 δ in = (R - 0.16 - δ 1 /λ 1 - δ 2 /λ 2 - δ i /λ i) × λ ut, in which R is the thermal resistance of the slope, wall or ceiling (m 2 × ° C / W), δ is the calculated thickness of individual structural elements in meters, and λ is the thermal conductivity coefficient of the insulation (W / m × ° C) for structural layers used.
In private house building, the formula is simplified to a simple equation δ ut = R × λB, where the last factor characterizes the thermal conductivity of the insulation used in W/m×°C. The minimum thermal resistance of walls, roofs and ceilings depends on the region in which construction is being carried out.
Table: thermal resistance values depending on the region of construction
| City | R (m 2 ×°C/W) | ||
| For floors | For walls | For coatings | |
| Anadyr | 6,39 | 4,89 | 7,19 |
| Biysk | 4,65 | 3,55 | 5,25 |
| Bryansk | 3,92 | 2,97 | 4,45 |
| Velikiy Novgorod | 4,04 | 3,06 | 4,58 |
| Derbent | 2,91 | 2,19 | 3,33 |
| Ekaterinburg | 4,6 | 3,5 | 5,19 |
| Irkutsk | 4,94 | 3,76 | 5,58 |
| Kaliningrad | 3,58 | 2,71 | 2,08 |
| Krasnoyarsk | 4,71 | 3,59 | 5,33 |
| Maykop | 3,1 | 2,8 | 3,5 |
| Moscow | 4,15 | 3,15 | 4,7 |
| Murmansk | 4,82 | 3,68 | 5,45 |
| Nalchik | 3,7 | 2,8 | 4,2 |
| Naryan-Mar | 5,28 | 4,03 | 5,96 |
| Nizhny Tagil | 4,7 | 3,56 | 5,3 |
| Omsk | 4,83 | 3,68 | 5,45 |
| Orenburg | 4,49 | 3,41 | 5,08 |
| Permian | 5,08 | 3,41 | 4,49 |
| Penza | 4,15 | 3,15 | 4,7 |
| Saint Petersburg | 4,04 | 3,06 | 4,58 |
| Saratov | 4,15 | 3,15 | 4,7 |
| Sochi | 2,6 | 1,83 | 2,95 |
| Surgut | 5,28 | 4,03 | 5,95 |
| Tomsk | 4,83 | 3,68 | 5,45 |
| Tyumen | 4,6 | 3,5 | 5,2 |
| Ulan-Ude | 5,05 | 3,85 | 5,7 |
| Chelyabinsk | 4,49 | 3,41 | 5,08 |
| Chita | 5,27 | 4,02 | 5,9 |
The thermal conductivity characteristics of any thermal insulation material can also be found in the tables.
Table: thermal conductivity coefficients of materials
To determine the thickness of the insulation, it is not at all necessary to count everything manually. You can use an online calculator, which is easy to find on the Internet. All you need in this case is to enter the values climate zone, attic area, type of insulation and scope of its application. The program will do all other calculations for you.
Insulating the attic from the inside
The simplest and in a convenient way roof insulation is thermal insulation from the attic side. Almost all known thermal insulation materials are used for these purposes. Mineral or glass wool is most often used - it does not affect high price these insulation materials. Extruded polystyrene foam is used a little less often, the installation of which causes more difficulties. And unfortunately, ecowool or polystyrene foam blowing is still very rarely used - the relatively high price and complexity of installing thermal insulation play a role here.
When insulating an attic from the inside, not only the walls, but also the floor are insulated
The durability of the materials used and the comfort inside the attic depends on how accurately the technology of thermal insulation measures is followed. The most important role here is played by how correctly the roofing “pie” is laid. If we consider the structure from the inside out, it consists of the following elements:
- finishing with sheets of plasterboard, plywood or OSB, clapboard, etc.;
- vapor barrier;
- thermal insulation material;
- waterproofing;
- counter-lattice and lathing with a ventilation gap;
- roofing material.
It should be noted that vapor barrier will be needed only when cotton wool materials are used for insulation - in this case it will prevent the penetration of moist air from the attic space. When using polyurethane foam or expanded polystyrene, there is no need for a diffusion membrane.
As for waterproofing, it is needed in any case, since it will serve as an additional barrier to protect the roofing pie and wooden elements of the rafter system from moisture coming from outside. If fiber insulation is used for thermal insulation, then superdiffusion membranes are used that are capable of transmitting water vapor in one direction. During installation, they are oriented in such a way as to ensure the removal of moisture from the cotton materials. In addition, to improve ventilation between the waterproofing and the roof, they install ventilation gap height from 5 to 10 cm.
When insulating with mineral wool, it is necessary to use a vapor barrier film
The entire process of roof insulation can be divided into several stages:
- preparatory work;
- preparation of thermal insulation material;
- laying insulation in place;
- fastening thermal insulation;
- finishing activities.
You should remember about insulating the attic space, starting from the design stage, not forgetting to take into account the features thermal insulation works at all stages of construction. You should decide from the very beginning what the attic walls will be like. If they act as inclined surfaces roofs up to the ceiling, then the roof slopes are insulated. In the event that vertical wall structures are installed, thermal insulation is installed on the affected areas of the roof, walls and adjacent areas of the floor.
Thermal insulation is installed in used areas
Work order
Before you begin thermal insulation of the attic, the insulation cake should be protected with a layer of waterproofing. This work must be done before laying the roofing material, otherwise it will not be possible to achieve complete tightness of the heat-insulating carpet. They begin to lay the film membrane directly on top of the rafters. The work is carried out from the bottom up, overlapping the previous canvas by 15 cm and gluing the joint with special tape. There is no need to tighten the film; it is better to leave a little slack. Deflection up to 20 mm per 1 linear meter there will be enough material so that the membrane waterproofing does not break with the onset of winter frosts. To attach the film to the rafters, it is best to use a construction stapler. If such a tool is not at hand, then the waterproofing can be nailed with galvanized nails with wide heads.
You should think about protecting the thermal insulation pie from moisture at the stage of roof construction.
To ensure normal ventilation of the space between the film membrane and the roofing material, lumber with a thickness of at least 25 mm is used as lathing. They are attached to the rafter legs using corrosion-resistant screws or galvanized nails 50–70 mm long.
To avoid accidental damage to the waterproofing film, holes are made in the sheathing in advance.
If the roof is covered with a soft roof, then a solid base made of particle boards, OSB or moisture-resistant plywood is mounted on the sheathing. Metal tiles, slate and other rigid roofing materials are attached directly to the sheathing elements.
Then installation is carried out from the attic side. To avoid making mistakes, you should follow the order of work:
- The thermal insulation material is unpacked. Slab and roll insulation laid out on a flat surface and left for a short time so that its fibers straighten.
- The mineral wool panel is cut into pieces, the width of which is 2–3 cm greater than the installation pitch of the rafter legs.
The standard width of rolled thermal insulation is 1.2 m, so for ease of installation, you should choose the same or halved distance between the rafters. In the latter case, the insulation is cut lengthwise, producing two sheets 0.6 m wide.
- Cut insulation boards are laid in the spaces between the rafters. Initially, the thermal insulation will be retained due to the installation “by surprise”, so each sheet is first pressed in the center, and then its edges are tucked in so that the insulation does not protrude beyond the rafters.
- The mineral wool is covered with a vapor barrier membrane. As in the case of waterproofing, strips of material are laid horizontally, from bottom to top, with an overlap of at least 10 cm. The joints are taped, and the film itself is secured to the rafters with staples.
- The bottom sheathing is made from lumber 2.5 cm thick. In the future, plasterboard structures or other finishing material will be attached to it.
The insulation layer is covered with a vapor barrier membrane, on top of which the sheathing slats are stuffed
Sometimes it is necessary to equip an insulated attic in a house with already installed roof. In order not to dismantle the roofing material, waterproofing membrane can be installed from the side of the room. To do this, the rafters are wrapped in film, and the material itself is attached to the sheathing. The disadvantage of this solution is that the wooden roof structures remain unprotected if moisture begins to leak inside for some reason.
Video: thermal insulation of the attic floor with mineral wool
Features of insulating an attic roof from the outside
If the design of the attic space assumes the presence wooden beams on the walls or its dimensions do not allow using a single centimeter of space, then the roof is insulated from the outside. It is best to do this at the stage of roof construction, since otherwise you will have to remove the roofing material.
Insulation of the roof from the outside can only be done with rigid thermal insulation. The best material in this case is extruded polystyrene foam. As noted above, such a coating does not require vapor barrier, so the insulation cake consists of fewer layers:
- slab thermal insulation;
- waterproofing membrane;
- sheathing with ventilation gap;
- roofing material.
The main advantage of roof insulation from the outside is the uniformity of the thermal insulation layer. An undoubted advantage is the absence of cold bridges and the possibility of inspecting and repairing rafters without dismantling the roofing material.
The method by which the attic is insulated from the outside will increase the internal space of the attic and use the rafters as decorative elements interior
Work order:
All that remains to be done is to lay and secure the roofing material. Rigid types of coverings are attached directly to the sheathing, so the distance between the beams should be taken into account at the stage of its installation. Under soft roof equip a solid base made of OSB or plywood, which is protected with a layer of waterproofing. In this case, there is no need to install a waterproofing membrane on top of the insulation.
Video: everything you need to know about attic insulation
Thermal insulation of an attic room, in addition to actually preserving heat inside, allows you to solve a number of other problems. High-quality insulation will prevent overheating of the roof in summer time, which means the room will be as comfortable as in any other room. In winter frosts, the thermal insulation cake will prevent snow from melting and ice from forming, and during rain or hail it will serve as protection from noise. It is only important to take into account the features of various insulation materials and carry out the work competently, taking into account the rules and installation technology.
Share with your friends!Arranging a living space in place of an attic has long ceased to be a rare occurrence. All more owners houses are interested in how to properly carry out repairs so that life “under the roof” is no less comfortable than in the house itself. Let's consider how to insulate an attic if the roof is already covered, what materials are best suited for this purpose and what nuances you should pay attention to.
An attic is not just a lived-in attic. There are some standards that distinguish these two premises from each other. First of all, the attic roof must have a slope. In addition, the height of the room established by the standard must be at least 2.5 m.
Focusing on attractive appearance, many decide to arrange an attic. But in reality, you have to deal with some nuances, which it is advisable to familiarize yourself with before starting work:
- the materials that were used to build the attic directly determine further heat loss in this room. Therefore, their choice should be approached very responsibly;
- No less influential are the correctly selected engineering solutions, which make it possible to ensure top floor all necessary communications;
- The shape of the roof plays a significant role. It can be single-pitch, gable or broken;
- in order to hide load-bearing elements roofs, you will have to use your imagination;
- the attic can be located not only on the territory of the house, but also extend beyond its boundaries, supported by columns.
Each of these aspects has its own influence on the approach that will be required for high-quality roof insulation. But the main role still belongs to two main materials - heat and water insulation. On the one hand, the space under the roof is in the coldest zone of the building. On the other hand, a strong difference between the temperature inside and outside often causes condensation to appear, which has a destructive effect on materials.
The best materials for do-it-yourself attic insulation
There are many suitable options for internal insulation of the attic. But your choice must be made based on the characteristics of the region of residence, as well as the design features of the specific roof with which you will be working. Let's look at what options exist today and what features are typical for them.
Insulating the attic with polystyrene foam: the pros and cons of the material
Polystyrene foam is one of the most famous insulation materials, which occupies its niche among inexpensive thermal insulation materials. Its price is indeed significantly lower than many others, but this is far from its only advantage:
- polystyrene foam does not absorb moisture at all. If the material is pre-treated with an impregnation specially designed for this purpose, then the water will simply flow down over the surface;
- light weight is another advantage, which greatly facilitates transportation and installation, and also reduces the load on the roof;
- the thermal conductivity of polystyrene foam is very low, so it copes with its direct functions more than fully;
- Styrofoam is easy to cut and attach. This allows you to work with it without any problems even if you lack any experience.
Interesting! In terms of cost, this method can only be compared with insulating the ceiling with expanded clay, although now this method is used less and less.
Based on these characteristics, we can conclude that polystyrene foam is an almost win-win option when it comes to insulating the attic from the inside. But insulating walls with foam plastic from the inside also has disadvantages, and sometimes they turn out to be much more significant than the advantages:
- the vapor permeability of foam is at a very low level. As a result, the room is often stuffy and hot. This also leads to increased humidity, which causes the development of fungi and mold on wooden roofing elements;
- despite its artificial origin, this material is often damaged by rodents;
- Over time, wood tends to shrink, which leads to the formation of gaps between the foam elements. It is impossible to fix this, and the only way to solve the problem is to completely replace the thermal insulation material.
Many believe that the listed disadvantages outweigh the advantages and insulating the attic with polystyrene foam is not justified. But one cannot help but admit that this is one of the most budget options, which causes a minimum of hassle, and if the installation technology is followed, it may well become an alternative to more expensive solutions.
Insulating the attic with polystyrene foam: advantages, disadvantages and features
Extruded polystyrene foam is very similar to polystyrene foam. Their specifications almost identical, with the exception of one significant aspect - installation technology. If polystyrene foam needs to be laid between the rafters, then polystyrene foam is placed on top, which eliminates the risk of cracks and gaps.
Helpful advice! Some manufacturers offer customers slabs with stepped joints, which makes the joints even stronger and more reliable. This fixation of elements together is an ideal option for insulating an attic roof.
Among other advantages of roof insulation with polystyrene foam, one cannot fail to note its low weight, which is perfectly combined with high strength and resistance to external influences. In addition, the service life of this material is quite long, provided that all the technology for insulating the attic with penoplex is followed.
Expanded polystyrene is not prone to rotting or decomposition, which is also important in the case of work on the roof. Any finishing coating can be applied over it, which will give an attractive appearance and provide additional protection.
Working with polystyrene foam yourself is easy: a variety of adhesive mixtures and mastics are suitable for fixing it. And in some cases they even use a construction stapler. So there is no need to purchase any expensive additional elements for installation.
But behind all these positive characteristics We must not forget about the only, but rather serious, drawback of insulating polystyrene foam from the inside of walls and roofs - the material has an increased level of flammability. For owners, this means the need for a more careful and thoughtful installation of all communications, in particular electricity.
Of course, manufacturers are trying to reduce this drawback to a minimum, but today we can say with confidence that this question remains open, and every owner who has chosen to insulate the walls from the inside with penoplex is obliged to take care of their safety.
Interesting! It is no coincidence that this material is most often chosen for insulating balconies. Expanded polystyrene has very low thermal conductivity, and at the same time on the balcony it practically does not have to come into contact with electricity.
Insulating the attic from the inside with mineral wool: a worthy alternative to penoplex
Mineral wool is another thermal insulation material that is used everywhere and is widely known for its properties. It got its name because of its fibrous structure, similar to medical cotton wool. You can buy it in rolls, which makes transportation and installation even more convenient.
Low thermal conductivity goes well with the ability to not absorb moisture. Although, if this happens, the material dries quickly without losing its appearance and technical characteristics.
Mineral wool belongs to the category of environmentally friendly and safe materials, which becomes noticeable even if the upper part of the roof is covered with metal tiles, which are prone to strong heating when exposed to sun rays. In addition, mineral wool also serves as a sound-absorbing barrier, and unlike polystyrene foam, it is not at all of interest to rodents and various insects.
Insulation of the roof from the inside with mineral wool must be done taking into account the fact that this is a fairly elastic material, even despite its soft fibrous structure. It is quite capable of being held between the rafters, provided it is properly fixed.
Helpful advice! In the process of cutting mineral wool for laying sheets between the rafters, it is necessary to leave a margin of approximately 2 cm. This will allow them to be held and not fall out even if there is no additional elements fastenings
Insulating the roof from the inside with glass wool: is it worth using this material?
According to its characteristics, glass wool is similar to mineral wool, but in in this case the fibers that make up the material differ longer, which generally increases the elasticity of the material. Strength indicators and soundproofing abilities are also slightly higher. But when in contact with moisture, glass wool is inferior to mineral wool, absorbing more water.
The use of glass wool for insulation of residential premises does not lead to any negative consequences for the health of residents. No toxic substances are used in the production process. In addition, glass wool is characterized by low flammability.
When working with the material, safety regulations must be followed to avoid glass wool fibers getting into the air. Its small particles can cause irritation of mucous membranes, and therefore the use of a respirator and safety glasses is a must.
Helpful advice! Sometimes glass wool fibers can cause skin irritation, so it is recommended to wear closed clothing and even gloves when working with it.
Do-it-yourself insulation of an attic roof from the inside using stone wool
Stone wool is the most expensive option among similar materials. But at the same time, it is the safest for human health and, in terms of reliability, significantly exceeds all other options. Here are some of its main advantages:
- The thermal conductivity coefficient of this material is one of the lowest;
- stone wool remains completely environmentally friendly even when heated;
- the layer of this heat insulator is also an excellent noise-absorbing barrier;
- the level of vapor permeability is very high;
- the material practically does not burn;
- no mechanical loads can deform stone wool or affect its characteristics;
- the material has a long service life;
- You can purchase stone wool in the form of slabs, which are easily cut into pieces of the required length and attached to the ceiling surface.
Due to the high cost of stone wool, they often try to replace it with mineral wool or glass wool. But such a replacement cannot be called complete, since this affects the quality of insulation quite seriously. Many users claim that the price of the material is quite justified, and provided that the installation technology is followed, it very quickly pays off the incurred costs.
Related article:
Types of insulation for roofs and ceilings. Mineral and synthetic insulation for roofs. Insulation of the attic roof.
In addition, it is quite possible to carry out all the work on insulating the attic roof from the inside with your own hands. Video instructions can demonstrate the procedure for carrying out the work, and recommendations from specialists will help you avoid common mistakes.
Insulating the attic with ecowool is one of the most effective ways to combat the cold
Ecowool is a pre-crushed material that is first blown into the cracks, and then, using the same method, a layer is placed between the ceiling and the rafters, using a device specially designed for this. This is an expensive procedure, but it allows you to completely eliminate all risks of drafts and ensure the most effective insulation.
Ecowool consists of 80% completely natural material - paper, the properties of which are very similar to those characteristic of wood. Given its natural origin, ecowool reduces the level of heat loss no less effectively than other materials.
One of the components that is part of ecowool is borax. According to its characteristics, it is an antiseptic natural origin, which makes it possible to provide wooden elements roofs effective protection from the formation of fungus and mold.
Ecowool is applied thin layer, but at the same time it provides a decent level of not only heat, but also noise insulation. The material retains its characteristics even after decades of use. So the not too low cost is the only drawback of this material, which is fully justified by its excellent properties.
Insulating the attic with polyurethane foam: basic technology and material features
Foamed polyurethane foam is the most modern of all the listed methods for insulating an attic. Its main difference is the complete absence of joints or gaps that could become a source of cold air. In addition, the service life of this material is one of the longest, up to 30 years.
Foamed polyurethane foam is not subject to shrinkage, even if wooden roof the house gradually begins to deform over time. Its solid structure completely eliminates the risk of moisture absorption, which eliminates the need to install an additional vapor barrier layer.
But there are also aspects that significantly complicate the process of using polyurethane foam as roof insulation with inside. This primarily concerns the application procedure, which requires complex and expensive equipment. Its purchase is almost never justified, so it is usually rented.
Another aspect - complex technology application, which requires certain experience in this field and does not allow beginners to independently cope with the task efficiently.
Helpful advice! The ideal option is to invite a team of workers who will come with their own equipment and in just a few hours will do high-quality insulation of the attic of your house.
Insulating the attic from the inside with your own hands using penofol
Penofol is a kind of foamed polyethylene - a technology that occupies its niche among the methods of modern insulation of walls and houses. Along with high sound insulation rates, it is also worth noting the fact that penofol has high-quality coating made of aluminum, which can be applied on one or two sides.
Here are a few more arguments in favor of using penofol for attic insulation:
- the material does not pose any threat to human health or the environment;
- its thermal conductivity is extremely low;
- the closed system of air bubbles characteristic of this material serves as an excellent barrier to steam penetration.
This method is also not cheap and requires significant financial investments. But, as practice shows, it is better to spend money on quality material and thereby provide comfortable living conditions for many years to come.
Combining materials is not at all uncommon. Materials with compatible characteristics can be used together for insulation. For example, mineral wool and polystyrene foam go well together. The first is placed between the rafters, and the second is placed closer to the edge of the roof. This combination will allow you to achieve the desired effect and significantly save on the purchase of materials.
Can provide reliable thermal insulation in combination with other materials
As you can see from the descriptions, each insulation has its own advantages and disadvantages. The only question is to choose the most suitable option, which will satisfy the idea of correspondence between price and quality of the material.
One of the most common mistakes that owners make is a rash choice in favor of the cheapest option for attic insulation. Videos and articles can demonstrate the positive aspects of a particular solution, but the choice must be taken into account all the nuances and characteristics. Attempts to save on thermal insulation material may lead to the fact that after some time of operation, you will have to carry out renovation work or even completely replace all the material.
Insulating the attic from the inside with your own hands: video and stages of work
Each material has its own fastening characteristics and should be used exclusively in accordance with the manufacturer’s recommendations. But if we talk about the general procedure for carrying out work, then there are mandatory stages that are carried out almost always, regardless of the material chosen.
The first layer of waterproofing material is laid out, which should protect the insulation from the destructive effects of moisture. The film is overlapped so that one layer overlaps the other by 10-15 cm. The material is secured using a construction stapler, and the joints are additionally taped.
Then, if necessary, a sheathing is created. For it, you can use wooden slats, the width of which is 8-10 cm. They need to be attached to the rafters, positioned parallel to each other at a distance of 50-60 cm. It is very important to check each element separately using building level. This will prevent any roof defects from occurring in the future.
A heat insulator is placed on the rafters or sheathing and secured in a suitable manner. For example, if we are talking about using any type of cotton wool sold in the form of rolls, then the material is cut into pieces the right size to lay them between the rafters. In this case, the thickness of the insulation should be such as to correspond to the width of the log. It is especially important if you decide to insulate the walls from the inside with mineral wool plus drywall. In this case, all free space must be filled with insulation.
The top layer of this “pie” is a layer vapor barrier material, which can be used as polyethylene film, glassine or roofing felt. As with waterproofing, the selected material is overlapped. True, in this case it is better to fasten it using thin wooden slats, placing them in increments of 40-50 cm. All joints must be taped.
Helpful advice! If you need to lay several layers of thermal insulation material, between each of them you need to lay vapor barrier film. This is especially true for cold regions.
As a final step, all that remains is to take care of a suitable finishing coating, which can be attached to the sheathing or, in the absence of it, directly to the bars. It is worth taking into account the weight of the used decorative panels, since installation of the heaviest of them may require preliminary installation of a frame made of a metal profile.
The main mistakes made in the process of insulating the attic
The final result of the work, which is done by hand, directly depends on how accurately the technology and all the prescribed rules are followed. It is worth paying particular attention to the procedure for laying the waterproofing layer, since materials that are capable of absorbing moisture subsequently dry out, which often causes cold in the room.
- if the roof slope does not exceed 13°, this will cause precipitation to remain on the surface. The result is rust and leaks. All this can negatively affect the condition of the insulation, so it is important to make sure that the angle of inclination is large enough before starting work;
- installation of thermal insulation material on the walls and roof is not all the necessary work. It is also necessary to take care of insulating windows (using Swedish technology). To do this, it is best to invite specialists to ensure that leaks are avoided. Especially if it is necessary to install windows at an angle;
- in order to provide the thermal insulation material with ventilation and the ability to dry out if it gets wet, it is advisable to leave a gap of approximately 2-3 cm between the material and the roof;
- you absolutely cannot miss at least one of required layers steam or waterproofing materials;
- If the thermal insulation material is thicker than the rafters, then their height can be increased by filling additional slats yourself.
These simple recommendations can help in the work process, significantly improving the quality of insulation. However, if for any reason there are doubts about the strength and experience, it would be better to invite a specialist. Of course, you will have to pay for this, but in this case you will not have to redo everything twice.
Insulating the attic gable from the inside is far from the most difficult task that a home owner may face. Often, owners want to place a balcony on the top floor, the insulation technology of which also has its own characteristics.
As with walls, a wide variety of materials can be used to insulate the ceiling on a balcony, although it is worth noting that loggia insulation technology is often used here, which has not been mentioned before. It will help you to understand in detail the features of this process. step-by-step instruction“Do-it-yourself insulation of a balcony from the inside.”
Do-it-yourself insulation of the attic from the inside with mineral wool: video instructions
As a clear example, it is recommended to watch a training video where the technology of insulating walls from the inside with mineral wool is presented in detail. This will allow you to familiarize yourself in detail with all the nuances and avoid the previously mentioned common mistakes.
The question of which insulation is best for the attic is relevant for those who have decided to equip a living space under the high pitched roof of a private house. The attic differs from an ordinary room in the house due to increased heat loss. This is explained by the fact that it usually does not have permanent external walls without window openings, and on both sides and on top the room is separated from the street only by a roofing system of small thickness.
Mineral wool insulation
Criteria for choosing insulation for the attic
High-quality insulation makes the attic suitable for year-round residence. When choosing a heat insulator, you need to pay attention to the performance characteristics of the materials, including comparing:
- noise insulation properties;
- ease of installation;
- moisture resistance;
- resistance to biological degradation;
- lifetime;
- efficiency;
- environmental friendliness;
- fire safety.
But the main quality by which insulation material is evaluated is its thermal conductivity coefficient, on which the ability to retain heat in a room depends.
From the point of view of ease of installation and use of insulation, preference should be given to universal materials. If the same thermal insulator can be used for walls, roof and floor, the insulation of all structures will last the same period.
Sound insulation properties are a particularly important parameter if the roofing is made of metal (seam roofing, metal tiles, corrugated sheets). Gusts of wind, rain and hail make such a roof “sound”, and staying in the attic will cause discomfort.
Slab insulation famous manufacturer Since the roof frame is usually made of wood, it is advisable to use insulation that is fire resistant and flame retardant. Otherwise, an accidental fire will cause the entire attic and roof to quickly become engulfed in fire.
To ensure that condensation does not form on the wooden structures of the rafter system and gables and that the insulation does not lose its thermal insulation properties due to moisture penetration, it is necessary to insulate the attic space with a vapor- and moisture-proof material, or to use reliable hydro- and vapor barrier. This affects the speed and complexity of installing the insulating layer and influences preferences when choosing a material.
Insulation thickness
Table 1. Dependence of insulation thickness on thermal conductivity coefficient
The manufacturer indicates the thermal conductivity coefficient on the packaging of the material. This indicator depends on the production technology and the density of the insulation. The table below shows the average values:
Table 2. Thermal conductivity coefficients of some insulation materials
Polyurethane foam and ecowool are modern materials that can be used as a heat insulator for attic spaces, but their installation requires the use of specialized equipment and the invitation of specialists. Other popular heat insulators are available in the form of slabs or rolled materials of varying densities and thicknesses.
The insulation is cut along the width of the span between adjacent rafters (or the gap between the sheathing slats on the walls) and inserted at random. If the calculated thickness of the heat-insulating layer exceeds the width of the rafter leg, bars of a suitable cross-section are placed on the rafters from the room side.
The most effective is considered to be two-layer insulation - after the gaps between the rafters are filled with heat insulation, another layer roll material(possible with a foil-coated vapor barrier outer surface) is attached over the rafters with continuous butted strips. This will eliminate the occurrence of cold bridges.
Laying thermal insulation between the rafters Let's take a closer look at the main pros and cons of popular insulation materials that are suitable for thermal insulation of attic roofs and gables.
Fiber roll and slab insulation
- glass wool;
- mineral wool;
- stone (basalt) wool.
Their key advantage and at the same time disadvantage is the ability to pass steam. Theoretically, wet warm air the attic will leave through the breathable internal lining, thermal insulation and roofing system, which will help maintain a favorable microclimate in the room. In practice, the following difficulties exist:
- an increase in the humidity of fiber insulation leads to a sharp decrease in its thermal insulation properties;
- insulation (especially glass wool) that has absorbed moisture becomes wrinkled and deformed, forming cold bridges;
- The wood of the rafter system begins to rot from contact with moisture.
To avoid these problems, it is necessary to install a vapor barrier on top of the insulation from inside the room. And between roofing covering and thermal insulation must be laid with waterproofing material.
Roofing pie with waterproofing over insulation Air exchange through fibrous insulation will only take place if the waterproofing and vapor barrier layer is made of special gas-permeable membranes. The vapor barrier should allow air to pass through, but retain moisture coming from the room. A gas-permeable waterproofing barrier must release moisture from the insulation and prevent water from penetrating into it.
Membrane materials are much more expensive than conventional or reinforced film, roofing felt or glassine. But these investments will pay off due to the durability of not only the insulation, but also the roof truss system.
Superdiffusion membrane If you use film as a vapor barrier, this will reduce the cost of construction, but this will reduce to zero the important advantage of fiber insulation - gas permeability. Perforated film should not be used, as it allows steam to pass through and will accumulate in the insulation.
Performance characteristics of fiber insulation
Glass wool. To her positive qualities can be attributed:
- fire safety (2nd degree of fire resistance);
- environmental safety (does not contain resins);
- unattractive to mice (they do not build nests and passages);
- affordable price.
The main disadvantage is that when working with the material, caustic glass dust is formed; installation of the heat insulator requires care and the use of protective equipment. In addition, over time, glass wool tends to deform and wrinkle, especially when moisture penetrates.
Mineral wool. The material contains fibers of various origins (manufacturing materials - clay, stone, quartz sand, glass, etc.). Mineral wool is characterized by a multilayer heterogeneous structure with air lenses. Due to this, the material dampens sound waves well. Choosing mineral wool (primarily Isover, Ursa) is recommended for those who have decided to make metal roofing.
This heat insulator is fire-resistant, does not rot, and is easy to install. But rodents can settle in it, whose nests, passages and waste products reduce the performance properties of the insulation.
Basalt wool. Consists of fibers obtained by melting rock. Withstands heat up to 1000 degrees, does not spread combustion. You should choose basalt wool carefully, checking quality and safety certificates: some manufacturers, in an effort to reduce the cost of products, use resins that emit toxic substances.
Basalt wool Basalt wool is resistant to fungus, but can be damaged by rodents. This is a good sound insulator and easy to install. But when choosing a material for insulating a rafter system, you should take into account the fairly large weight of stone wool slabs.
If you have to choose a fiber insulator, pay attention to the density of the material. The heat insulator should not lose its shape even after prolonged use. For mineral, basalt wool, the density indicator should be about 40-45 kg/m3.
Polymer materials for insulation
We choose a polymer heat insulator for the roof and walls of the attic. This can be polystyrene foam, extruded polystyrene foam (these two types of insulation are available in the form of sheets and slabs of various thicknesses), as well as polyurethane foam, which is applied to structures by spraying.
The advantages of polymer insulation include low weight and low thermal conductivity. Such thermal insulation will not overload the rafter system and will successfully cope with the task of retaining heat.
The disadvantages of polymer insulation include extremely low vapor permeability. There is no gas exchange through insulated structures, so you cannot do without a well-thought-out ventilation system in the attic.
Insulation of the attic with polyurethane foam Thermal insulation made of extruded polystyrene foam (penoplex) and polyurethane foam will not allow heat and steam to pass through to the roof rafter frame, therefore, there is no need to install a vapor barrier on the room side. Despite the fact that the dew point at internal insulation gables will shift towards the heat insulator, moisture, dangerous for wood, will not condense.
All joints and junctions of foam insulation must be filled polyurethane foam and (after removing excess foam) taped with reinforced tape so that the insulation layer is airtight.
Manufacturers produce penoplex of various densities. For pitched roof and attic walls, where heat loss is high, it is advisable to use slabs with a density of 30-35 kg/m3.
If you decide to choose inexpensive foam plastic, it is better to install insulation according to the same principle as fiber board materials. Unlike extruded polystyrene foam with a continuous closed-cell structure, polystyrene foam consists of many individual granules pressed into a slab. Technological pores remain between the structural elements, which are capable of allowing steam to pass to wooden structures.
A suitable foam density is 35 kg/m3; at a break, the material should not crumble into individual balls. Since polystyrene foam smolders when ignited, releasing toxic substances and is easily chewed by mice, it is not the best material for internal insulation.
Polymer insulation for the attic should not be considered as a soundproofing material for the roof - it will not save you from the sound of raindrops. But if you insulate the floor with it, it will reduce the vibration load from steps, creating acoustic comfort in the rooms under the attic.
The selected insulation option will last for many years if you purchase good material and take into account all the details of its installation.
