Which insulation for the attic roof is better to choose -

10-08-2018

Roof

The arrangement of the attic with the right approach solves the problem of shortage of living space in a residential house. But in order to use the all-season heat insulation under the roof, high-quality thermal insulation will be required, especially if the construction site is located in central Russia or even further north.

The market for building materials offers to solve this traditional and new ways. In order not to get lost in the abundance of materials, our article will tell you what insulation is better suited for the attic roof and the pediment, how to choose and install it.

Heat transfer in the attic

Attic thermal insulation is a relatively new construction technology, which became popular after the heating reached the roofing rooms. In the attics, which are not heated, insulation is not so important. After all, the air gap between the ceiling and the slopes covered with a snow cap perfectly retains heat in the living rooms. The installation of the heating system in the attic floor changes the situation in the opposite direction: the heated air rises to the ridge and transfers its heat to the roofing material, due to which the snow from the roof melts. To reduce energy loss, it is necessary to provide for the insulation of the mansard roof and the pediment in one of the most popular ways:

Thermal insulation mansard roof inside. This method consists in laying sheets of thermal insulation material between the roof rafters. This is a more cost-effective method of insulation, however, after the completion of the construction of the roofing structure, this is the only possible solution to the problem of energy losses. To achieve a greater effect, insulation should be mounted from the inside, complete with a vapor barrier.
Thermal insulation outside. Experienced roofers consider this method more rational, since when laying the insulating material cold walkways are not formed. Warming the mansard roof outside occurs during the installation of the roof: a layer of insulation is placed on the vapor barrier membrane, fixed with a construction stapler over the rafters. After that, the insulation is protected with a waterproofing film, the sheath is nailed and the roofing material is mounted.

Compared with the insulation from the inside, the outside is less protected from moisture. In addition, in order for the weight of the roof and the snow not to damage the integrity of the layer, materials that can keep the shape well are chosen for external insulation.

General material requirements

Although the quality and method of installation to some extent affect the efficiency of insulation of the mansard roof and pediment, the main thing is to correctly determine which material will cope better with this task. The builder claims that good insulation should have the following qualities:

Resistance to external factors. For insulation of the gable and the mansard roof, it is important that the thermally insulating material withstand sudden changes in temperature, repeated defrosting cycles, freezing, without cracking, without changing its shape and structure.
Low hygroscopicity. Insulation for the gable and roof of the attic has a low hygroscopicity, that is, it does not absorb moisture. Since an increase in humidity reduces the efficiency of thermal insulation by half, it increases the weight of the roof structure and leads to the formation of mold and rot.
Low thermal conductivity. Materials with low thermal conductivity do not heat up and “seal” the heat from inside the room, reducing heating costs of the attic.
Security. For gables and roof trim use insulation with a high class of fire safety, non-flammable and does not support combustion. In addition, it is better to use materials that are not harmful to health and do not cause allergies.

Comparative characteristics of thermal insulation materials

The thickness of the insulation layer of different materials

When deciding which material is better to use for roof insulation, note that the thickness of the layer is selected depending on the climatic conditions in the construction region - for central Russia it is recommended to use insulators with a thickness of at least 150 mm.

Types of materials

Mineral insulation materials

This category includes fiberglass insulation, produced in the form of a roll or slab, called mineral wool. They are made from glass industry waste and metallurgical production. But for warming the attic, builders recommend basalt-based stone wool. Its working temperature is 800-900 degrees, it does not burn and does not sustain combustion, it has high thermal insulation and sound insulation characteristics.

Usually, stone wool is used for warming the gable and the roof from the inside, since the plates, and especially the rolls, have a rather soft structure, crushed under the weight of the roofing material. The thermal conductivity of this type of insulation is 0.035-0.04 W / m, but during operation and accumulation of moisture, this value increases by half after 3 years of use. Therefore, for effective thermal insulation requires protection of mineral wool from moisture with the help of waterproofing and vapor barrier.

Polymer insulation materials

Recently, builders began to make extensive use of materials based on polystyrene foam to insulate the gables and roofs from the inside or outside. This method has become the most popular method for the reconstruction of old houses. It possesses the following operational qualities:

A light weight. Insulation layers based on polystyrene foam weigh a few grams, so they do not increase the load on the roof system.
Низкая гигроскопичность. Styrofoam абсолютно не впитывает влагу, поэтому не страдает от сырости, плесени, не теряет свои термоизоляционные качества в процессе эксплуатации.
Does not conduct heat and sound. These properties make expanded polystyrene indispensable for houses located in the passage area of busy roads and buildings with resonating roofing materials (metal tiles, corrugated flooring), which increase noise during rain.
Fire resistance Insulation based on polystyrene foam does not burn, but slowly melts, therefore it is considered safe.
Easy installation. A wide range of material thickness from 10 to 500 mm facilitates its use for self-assembly. Also for its installation does not require a special tool, and you can cut the seams with a knife or saw.

The only drawback of polystyrene is fragility. During installation and operation of the sheets are easily damaged, crumble. But this problem is solved by the use of extruded polystyrene foam, which is blown with special equipment under the film between the rafters of the roof.

Natural insulation materials

Those who primarily value environmental safety, as well as the natural origin of materials, should take a closer look at natural insulation for roofing. They are made from the fibers of industrial crops - hemp, flax. In addition to cellulose, ecowool contains 12% of antiseptic and fungicidal additives and 7% of fire inhibitors. Operational characteristics of natural insulation compared to mineral:

Low thermal conductivity. The thermal conductivity of ecowool is lower than that of mineral materials, they are 0.032 W / kg.
Ecowool absorbency is two times less than that of mineral heat-insulating materials based on glass, basalt, slag.
The flammability class is G1-G2, that is, in fire-fighting terms, ecowool is less safe than mineral-based insulation.
Ecowool has a looser structure than the mineral one, its density is 30-75 g / cub. m
Natural types of thermal insulation materials absorb sound better by 10%.

Experienced builders say that eco wool is the best material for warming inside log, frame, log houses with an attic, because its characteristics are close to the properties of natural wood, its use reduces heating costs by 30%.