Mineral wool insulation

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In this article, you will learn about the advantages and disadvantages of mineral wool insulation. Consider several popular misconceptions that are associated with the properties of mineral wool, whether it is harmful to health. In the article you will find a method for selecting the class and thickness of mineral wool insulation.

Mineral wool insulation

The first step is to dot the “i” s, dispelling several popular misconceptions that exist in the field of near-construction reasoning. There are a number of myths about mineral wool, which significantly complicate the procedure for choosing this material..

Myth number 1. Reliable manufacturer

It is certainly pleasant to deal with “Ursa”, “Knauf” or “Rockwool”. The well-known name and the mention of a reliable country, be it France, Finland or Germany, inspire confidence when choosing a good insulation. At the same time, the fact that technical wool is produced using a single technology, on similar equipment from identical raw materials, falls out of sight..

Here it is appropriate to recall the main function of mineral wool – reliable thermal insulation, which is achieved by keeping stable air between the fibers. Even a bunch of cut hair is capable of this, if properly organized. The principle of blowing cotton wool and thermochemical reactions have not changed over 150 years of its existence, therefore, modern mineral wool insulation of the same brand and class really does not differ much..

Video about mineral wool insulation

Of course, this is not a reason to purchase dubious products at suspiciously low prices. Do not forget about the striving of our compatriot entrepreneurs for unreasonable savings. However, large manufacturers, especially joint Russian-European enterprises, keep the quality at the level.

Factory technology for the production of cotton wool – step-by-step video

Myth number 2. To select mineral wool, a heat engineering calculation is required

Undoubtedly, calculations are a useful thing, sometimes even necessary. However, this procedure is quite expensive if you hire a company, and it is difficult to carry out calculations on your own without appropriate education and experience. There is a high probability of making a small error of 0.01 units or coefficient, which will devalue subsequent calculations.

Mineral wool insulation

The good news is that over 150 years of its history, mineral wool has been 100% studied and classified according to three criteria, combining which, you can select the necessary parameters of the layer and material. All heat engineering calculations will be reduced to these parameters:

  1. Form – plate or mats.
  2. Brand (density) – measured in kg / m3.
  3. Layer thickness.

You can select these parameters, guided by the wide experience of using wool insulation, as well as the manufacturer’s recommendations.

Myth number 3. Mineral wool – harm to human health

It is difficult to deny that a substance produced using chemical reactions will not be completely passive. In the technological process, there is a moment of introduction of formaldehyde resins, which evaporate after molding and packaging. Their vapors are indeed carcinogenic and harmful. The particles of stone raw materials themselves are also harmful. But the evaporation rate and actual particle concentration are so negligible that they are simply overlooked in product descriptions..

Modern mineral wool is called environmentally friendly because the amount of carcinogens (and any other harmful substances) is ten times less than the maximum permissible concentration (MPC) threshold, not only in a working (“cold”) state, but also under strong heating (wool itself does not lit). These and many other harmful resins are found in chipboard (furniture), OSB (bases and surfaces), in all types of plastics, including window.

Frightening articles that mention Greenpeace, environmentalists and phrases like “… in Europe have long been abandoned …”, “… all over the world have switched to harmless heaters …”, etc. are unfair marketing designed to draw attention to an alternative product ( PPR, liquid polyurethane foam, insulating plaster, etc.). When choosing a heater, remember that absolutely passive substances do not exist in nature and industry..


  1. Choose mineral wool from manufacturers available in your area. Pay attention to the proximity of the factories – if the production is far away, you risk overpaying up to 15% for transport (included in the price).
  2. Layer thickness and grade can be selected from experience. It all comes down to the number of layers of factory thickness of 50 or 100 mm.
  3. Mineral wool is a modern, harmless material. To argue otherwise is tantamount to saying that the car itself is obsolete, citing the 1921 Ford-T as an example..
  4. Mineral wool is not a panacea and not an ideal material. All other heaters have their own merits..

Mineral wool insulation

Mineral wool is available in two formats – slab and roll (mats). The packaging must have a two-digit number from 11 to 66 – density, that is, the main indicator of the constructive value of cotton wool. Rigidity and bearing capacity directly depend on it. In different cases, different indicators are relevant. Consider the main cases of using mineral wool in private construction and repair in order of increasing density.

Noise insulation of floors

For this purpose, mineral wool mats of the lowest grade are suitable – 11-14. This is due to the fact that there are no temperature and humidity fluctuations in the internal floors of the building..

Mineral wool insulation

Noise insulation of partitions

For this, mats of higher density are suitable – from 30 to 37 gk / m3 or plates with the same performance. This is due to the requirement for vertical stability of the non-bearing layer of insulation, which are imposed on partitions. It should just stay in the cell under stable temperature and humidity conditions..

The layer thickness in these cases is determined by design capabilities. The ideal option is to fill the entire thickness of the slab.

Roof insulation up to 45 °

The closer the slope is to the horizon, the lower the density is required to maintain the stability of the layers. The thickness of the insulation is usually equal to the width of the rafters (150-200 mm). In any case, you should never save on roof insulation – we are talking about blocking 40% of heat losses that pass through the roof. The money saved for one layer will be overpaid for heating within 2–3 years. You can use mats and boards with a density of at least 30 kg / m3.

Mineral wool insulation

Insulation of the roof over 45 °, mansard roof, outer walls of a frame house

Usually, insulation in these cases is made from the inside, by installing mineral wool between the edges of the frame. In this case, the sheet should stay in the cell for some time without filing. If the sheet falls out under its own weight, a denser, stiffer insulation is required. Plates not lower than 37-42 kg / m3.

External insulation of a ventilated facade with dowelling

In this case, the cotton wool must be dense enough to withstand the dowel pressure. Sufficient density 37-42 kg / m3. For a wall of 1–1.5 bricks, 100 mm mineral wool is enough.

Mineral wool insulation

External insulation under the “wet” facade

The highest requirements are imposed on this type of plates not only in terms of thermal conductivity, but also in terms of rigidity. The structure of the sheet must withstand the weight of the finishing layers, so the density is required at least 42 kg / m3. often the packaging of such cotton wool is marked “FASAD”. For a wall of 1–1.5 bricks, 100 mm mineral wool is enough.

Internal thermal insulation of baths, saunas

Inside the room there is no need to “scatter” centimeters of the layer, and a thin heat reflector comes to the rescue, which is factory-glued onto sheets (rolls). This negates the possibility of vertical shrinkage of the material. Foil insulation with a density of 14-37 kg / m3 has sufficient resistance to thermal conductivity and a thickness of only 50 mm, but at the same time it is much more expensive. In other words, in this material 50 mm of cotton wool is replaced by foil with a thickness of about 0.5 mm..

When choosing mineral wool, remember that about 50% of problems with insulation occur due to errors or negligence during installation. Since these are hidden works, their control must be strengthened. The insulation should be in the structure in its natural position – even and smooth. Creases, bumps, waves, wrinkles, overlapping seams are popular causes of rockwool malfunction and sagging. Observing the installation rules and operating standards, you will ensure a long and calm life for yourself and your home.

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