What Is The Best Insulation For The Attic: Choose The Best Materials For Insulation Of The Attic Roof

A mansard is a landscaped attic that is often used as a living room or additional technical room. It is different in that it requires increased thermal insulation, since it has a large area of contact with the cold atmospheric environment.

Depending on the purpose of using the attic, select insulators that differ in thermal conductivity, density, flammability. Let's understand what is better to insulate the attic, so that it from a cold attic into a habitable or storage room.

Content of the article:

  • Warm attic - extra living meters
  • Overview of insulation materials for roofing
    • Option #1 - glass wool
    • Option #2 - mineral wool
    • Option #3 - ecowool
    • Option #4 - foamed polystyrene
    • Option #5 - extruded polystyrene foam
    • Option #6 - sprayed polyurethane foam
    • Option #7 - PIR boards
  • Area floor insulation in the attic
  • Conclusions and useful video on the topic

Warm attic - extra living space

However big the room is, There is always a need for another room - a guest bedroom, a playroom, a gymnasium, or just a handy storage room.

According to the normative documentation, an attic is a room formed by the façade and the roof deck. According to the sanitary regulations, the distance from the floor to the line of intersection of the wall with the roof should be at least 1.5 m, and to the ceiling - 2.5 m. In this case, an area with a \"high\" ceiling (2.5 m or more) must occupy from 50% of the total area of the attic.

Obviously, in private housing there are deviations from the standards. For example, factors such as the shape and size of the roof may influence the configuration of the attic space: homes with high roofs have higher attic ceilings but narrower floor areas.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

One of the good uses of the attic space is as a small living room for adult family members to relax or children to play. Here you can find a little privacy for reading or doing crafts

In order to increase the size of the attic, various methods are used: increase the height of the lower story with a sloping roof, make the facade walls higher.

But for all the advantages of an additional comfortable room there are nuances that increase the cost of construction and finishing work:

  • installation of windows;
  • fitting of ventilation;
  • water and thermal insulation.

The last point is also important because you have to insulate literally everything: the floor, gables, walls, often consisting of two parts - the facade and the roof. In this case, insulating materials have the same requirements as those for insulation for residential premises. In addition to suitable technical characteristics they must be absolutely safe.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

Example of how the shape and height of the roof may influence the size of the attic - therefore the features of the underroof space must be considered when planning the living space

Overview of thermal insulation materials for roofing

In the market today you can find everything from the tried and tested glass wool to natural and foiled materials, which are still less common in practice. Consider the best way to insulate the walls and floor of the attic from the inside, so that the attic was warm, and in the near future did not have to make repairs.

Option #1 - glass wool

Glass wool has gained popularity due to its low cost, so if you want to save on insulation, you can use roll mats or more convenient to install the plates. The raw material is specially purified quartz sand and waste from the glass industry.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

The low weight of glass wool makes it easy to install and the load-bearing structure of the roof is not increased

In addition to its affordable price and light weight, it offers the following advantages:

  • elasticity, which allows the boards or mats to be laid tightly against each other and rafters;
  • flexibility, useful when insulating difficult roof areas;
  • unattractive to rodents, which is due to the absence of natural materials in the composition.

Disadvantages, however, are also sufficient. For example, they include high hygroscopicity, requiring the use of a vapor barrier on the inside and ventilation to evaporate moisture - on the outside.

Due to the fragility of glass fibers is destroyed, and the smallest particles of it are spread in the air, creating a dangerous environment for health. In addition, questionable companies use formaldehyde as a binder, so it is better to use a more expensive but safer material.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

If you want glass wool to last, not to get wet from condensation and not to shrink in the first years after installation, buy products from proven manufacturers, which may include \"Isover\" or \"Ursa\"

For example, the \"pitched roof\" from \"Isover geo\" line is not only safe for residents, but also refers to non-combustible materials.

Option #2 - mineral wool

Unlike glass wool, mineral wool is made from the melt of igneous rocks, which form a less brittle, more durable and resilient material during processing. Accordingly, the performance properties of this insulation are higher.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

Basalt wool slabs have a smooth, uniform structure that makes them easy to install. At the same time, the material particles do not disperse and do not cause a negative reaction to the body

Moisture absorption is lower than that of glass wool, but moisture is still absorbed, so it is not necessary to refuse vapour barrier during installation works. Vapor permeability in the normal range, and if you create the right conditions for the evaporation of moisture from the surface, the material will last a long time.

Brand products do not contain harmful substances in their composition, which is guaranteed by the sanitary certificate. If you doubt the safety of insulation, ask to see the documentation when buying.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

The resilience of the material is demonstrated by the fact that the material increases in volume by half or two times after removal of packaging, while maintaining its performance characteristics at 100%

Modern basalt thermal insulation is easy to lay, this is accompanied by some developments of manufacturers. For example, Rockwool boards have a spring-loaded edge area that ensures a snug fit, reliability and stability.

The main drawback of the popular brands among builders - Tekhnonikol, PAROC, Isoval, Rockwool - is the price.

Option #3 - ecowool

The real discovery was the organic-based material - ecowool. The cellulose fibers, which are obtained by processing wood, cardboard, recycled materials, demonstrate excellent thermal insulation qualities.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

The composition of the material is as follows: 82-85% cellulose, another 15-18% are binders, antiseptic additives and flame retardants. The inclusion of protective components protects the insulation against biological decay and combustion

For many technical characteristics ecowool is \"on the heels\" of mineral counterparts:

  • thermal conductivity - 0.038-0.043 W/m×С°. Thermal conductivity - 0.038-0.043W/m×°C;
  • combustibility - G2 (self-extinguishing, slightly flammable);
  • layer density - 45-75 kg/m3.

The name \"ecowata\" speaks for itself - the material is environmental friendly, contains no hazardous toxic substances. However, thanks to the antiseptic treatment it does not attract rats and is protected against rotting.

The disadvantage of ecowool is its high degree of hygroscopicity, so the installation estimate must include besides the roll or sprayed material waterproofing polyethylene films or polymer membranes.

There are two ways to lay ecowool when insulating an attic: \"dry\" and \"wet\".

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

If the roof on the inner side has a negative slope, the technology of blowing dry insulation into the space created between the roof structure and the vapor barrier film or inner sheathing

The \"wet\" method of applying ecowool on the roof elements from the inside uses an adhesive solution that ensures maximum adhesion of the material to the base and increases the strength of the thermal insulation layer.

The main disadvantage of insulation is the availability of special equipment for laying. Installers must have special skills, without initial experience it is better to choose easier to install materials - for example, mineral wool in slabs.

Option #4 - foam

Inexpensive but questionable material for insulating attic spaces. Let's try to understand why it is undesirable and even dangerous to use foam plastic in the process of thermal insulation works.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

Foam plastic continues to be used due to the whole complex of attractive features: it has low weight, costs much less than other insulators, easy to install and transport, has good thermal insulation qualities

But the shortcomings of the material become a strong argument against its use.

The disadvantages are the following:

  • often foam does not meet the claimed characteristics, as it is produced everywhere without taking into account any technical requirements;
  • it is a flammable material, emitting toxic substances in a fire - as we know, people die in the first minutes after a fire not from the fire, but exactly because of poisoning by combustion products;
  • foam is quickly destroyed - breaks down into separate granules, so that its thermal insulating qualities are lost.

Manufacturers who are serious about the quality of their products take measures to improve them. However, even the well-known brands of boards are inferior to other materials in terms of performance. By the way, in European countries foam plastic is forbidden for usage in habitation, while our compatriots keep on saving money and putting their families at risk.

Option #5 - extruded polystyrene foam

The other thing is extruded polystyrene boards which is different both in production technology and in its performance characteristics.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

The foaming and gas filling process results in a homogenous structure of small insulated cells, a material of high water and thermal insulation and high strength

EP is more expensive than plastic foam, but the advantages of the material force one to overlook the price difference and to prefer it.

The advantages of extruded polystyrene foam include:

  • thermal conductivity coefficient - 0.030 ±0.032 W/m×°C on average;
  • very low degree of hygroscopicity;
  • maintained board geometry that does not change over time;
  • durability due to protection against water ingress;
  • flammability class - G2, characterized by self-extinction.

Unfortunately, in case of fire foamed polystyrene also produces toxic substances, even if not in the same extent as foamed plastic - do not forget about it.

Thanks to the sophisticated manufacturing technology there are almost no fakes in the market - only serious enterprises can afford to produce insulation.

All disadvantages are rigidity and lack of flexibility. Unlike resilient mineral wool, EP boards are difficult to adjust to certain sizes so that after installation there are no gaps between them. Usually, the gaps between them are filled with assembly foam or other sealant.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

The boards are often installed not between rafters, like mineral wool, but above or under them. Sealed with sealant at the edges they form a continuous band

This method is often used when one wants to create a loft style interior: the beams that are openly located under the layer of insulation and inner linings look more than picturesque.

There are leaders among manufacturers of extruded polystyrene foam. For example, the products of the brand \"Penopleks\" are widely known, the name of which has already become a proverbial. Quality boards are characterized by the fact that they do not require the mandatory use of waterproofing and are quite suitable for creating a continuous roofing crate.

The rules of work with extruded polystyrene foam are described in this material.

Option #6 - sprayed polyurethane foam

The sprayed foam insulation on the inside of the roof is a great way to create seamless, durable insulation without cold bridges and seams requiring filling. One of the best quality \"sprays\" is polyurethane foam, which creates an effective thermal insulation layer.

Benefits of sprayed insulation:

  • Heat transfer coefficient - 0.03 W/m×°C or less;
  • no vapour barrier required;
  • good adhesion to various surfaces;
  • no previous preparation;
  • minimal load on rafter structures.

The thin but dense layer created by cured FPU is also an excellent acoustic protection, important for a loft used as a bedroom.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

Polyurethane foam insulation is not dangerous for people and animals after curing: it does not release toxic substances into the air, does not deteriorate, does not provoke mold and mildew

Polymer foam insulation, besides other advantages, has a corrosion resistant effect: metal parts treated with FPU do not rust, receiving additional protection. Polyurethane foam is also impermeable to moisture, so it is considered an excellent waterproofing material.

The disadvantages are high cost, the need for spraying equipment. It is not possible to insulate by oneself without special training, that is why one more expense item is the services of a team of trained installers.

Option #7 - PIR boards

Not so long ago a material appeared in the market that combines the positive qualities of popular insulators: thermal conductivity of polyurethane foam, durability and hydrophobicity of extruded polystyrene foam, fire resistance of mineral wool. These are PIR boards - products made of polyisocyanurate foam having a rigid structure with small cells filled with gas.

The main achievement of PIR board producers is considered to be the thermal conductivity coefficient reaching 0.022 W/m×°C.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

With a density of only 40 kg/m³ the insulation has a relatively high strength of 120 kPa and temperature resistance ranging from -70 °C to + 110 °C

In addition to conventional boards, foil products are also produced that are further protected against moisture by a thin metalized layer. The boards are connected to one another with tongue and groove joints so that large seamless areas can be created on even surfaces.

The leaders among insulation manufacturers have already adopted new developments and are producing PIR boards under their own brands. For example, products from the company \"Tekhnonikol\" are becoming popular, and the manufacturer specializes in the production of insulation for all types of building structures.

What is the best insulation for the attic: Choose the best materials for insulation of the attic roof

Polyisocyanurate foam plates have standard, convenient for installation dimensions. For example, \"Tekhnonikol\" products are 1200*600mm products with thickness of 25-150mm

Widespread distribution of products superior in technical characteristics to analogues is hindered only by high cost. 13-15 thousand rubles per cubic meter of material - this is really expensive compared to mineral wool or polystyrene foam.

In addition to the listed best types of insulation for the attic also use mats of natural wool, expanded clay and even wood-fiber boards, but these materials are not as common because of unsuitable for some reason characteristics or have a complicated installation technology.

Ways to insulate the floor in the attic

Whatever warm the walls in the attic, it is necessary to insulate the floor, especially if the room will be used as a bedroom or playroom. It should not be forgotten that this is also the insulation of the ceiling of a one-storey house or the upper floor in a 2-3-storey building.

When insulating the attic floor it is necessary to remember two conditions:

  • the material must be light and not create a load on the ceiling;
  • the thermal insulation characteristics must be high.

Glass wool, ecowool, mineral wool, extruded polystyrene foam, PIR boards can be used to meet these requirements. Thermal insulation is laid under the final cladding, for which usually choose treated boards.

The advantages of insulators:

Image Gallery

Photo of

Eco-wool-when sustainability comes first

Glass wool - cheap and easy

Basalt wool - warm and dry

Polystyrene foam for a flat floor

Exact advice, What material is better to finish and insulate the attic, it is difficult to give advice, since much depends on the climate in the region, the size of the attic space, the characteristics of the roof covering and the rafter structure. Not the last place also occupy the financial capacity of the owner of the housing.

We also recommend to read the step by step instructions on insulating the attic with their own hands. For more - follow the link.

Conclusions and useful video on the topic

An example of insulating the attic with mineral wool:

Technology of blowing thermal wool:

A universal material - rock wool. Full review from the manufacturer Technonikol:

When choosing insulation, do not forget that the attic is a living space, which should not only be warm, but also safe. If possible, buy materials that comply with sanitary norms, with a suitable flammability class and absence of toxins in the composition.

And the best characteristics of thermal conductivity, stability and hygroscopicity guarantee comfortable use of the room for a long time.

Which of the insulators for the loft did you give your preference and why? Are you satisfied with the result? Please share your opinion with the visitors of our site. Leave your comments in the box below.


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