Insulation of the roof from the inside with mineral wool

The popularity of mineral wool insulation is explained by the rather high thermal insulation properties, ease of installation and relatively low cost. To some extent, the result from their use is slightly lower than the sellers and manufacturers promise, but even this is enough for many of those who are building a house with their own hands to choose this material for roof insulation.

Currently, the main methods of insulation using mineral wool are:

Inter-rafter insulation.
Complete roof insulation.

Let's talk about both options.

Selection of material

When purchasing products, first of all listen to the manufacturer.

Very often, when buying a particular roof covering, an instruction is attached to it, which should indicate what materials it is in good contact with. For example, metal tiles or corrugated board, however, like all other metal coatings, become a place for moisture accumulation and you can remove it in two ways.

The first method is to prevent moisture from entering the roofing cake. For this, waterproofing and vapor barrier products are used. As for the second, everything here will depend on the created system of natural ventilation. Understanding what suits you best will help the answer to the question: "what will be your roofing cake?" By design features, the roof can be:

Cold.
Here, the attic space can only be used as a storage room. By the way, in most cases, the villagers do this.
Warm.
If you decide that the attic space will be insulated, then you can think about a residential attic. The structure of the roofing cake will be much more complicated, more materials will be spent on its arrangement, but all this will be leveled out by additional residential squares.

Once you have decided on the purpose of your attic, you can start thinking about waterproofing products or how to get quality ventilation.

Vapor barrier materials

The most popular vapor barrier material is a special film that protects wood and insulation from the effects of steam, which turns into condensation as a result of temperature changes. The negative impact of moisture on the elements of the roofing structure can be ignored once again - suffice it to say that it significantly reduces the service life of the roof and the effectiveness of the heat-insulating material.

The vapor barrier membrane is attached to the roof or slab before the thermal insulation materials are installed. In rooms where heating has been carried out, the vapor barrier must be installed only under the finishing layer. To protect structures that are constantly in temperature contrast conditions, a vapor barrier layer must be placed on both sides. The exception is concrete floors, which do not require such protection.

For arranging the vapor barrier layer, a film with different characteristics can be used. The simplest option is a nonwoven film, but a foil membrane is a much more efficient option. The last option, as its name implies, has a thin foil layer on one side, which prevents heat from escaping outside the structure.The roof vapor barrier installed from the inside of the house is connected with special tape, which ensures a tight connection.

How to install waterproofing under a cold roof

Typically, cold roofs are created from a standard set of materials and structures, namely:

Lathing and counter-lathing. This system can be created both from lumber and from metal, the main thing is that the ventilation ducts do their job well. In the case of using wood, the counter-lattice will create an air gap that will allow gusts of wind to blow excess moisture out of the roofing cake.

Waterproofing product. For cold systems, it is best to use special membrane films that protect wood and metal products from all types of precipitation. They can be mounted on top of the crate itself, before installing the roofing material or under the crate, so that moisture does not come from inside the living quarters. However, you can combine the two methods and get a closed roofing cake, reliably protected from moisture on both sides.
Finish coating. In this case, a metal tile or profiled sheet will be used.

IMPORTANT: This kit is often used on outbuildings or on simple roofing systems in private houses. This is a great option if you want to save a ton of money and time.

Types of mineral wool

Varieties of mineral wool for roof insulation

Depending on the material that serves as raw material for the manufacture of mineral wool, there are 3 types of mineral wool:

Glass wool.
Basalt or stone wool.
Slag wool.

Glass wool

In the production of glass wool, the same materials are used as for the manufacture of ordinary glass. Under the influence of high temperature, all components are melted and then in special centrifuges they are blown up with steam to form thin glass filaments. Then the fiber is treated with binding materials and after drying it is given the desired shape.

Glass wool for roof insulation

The thickness of the glass wool fibers can be from 5 to 15 microns.

Advantages of glass wool:

Retains its properties at temperatures from -60 ° C to + 450 ° C.
Has a high level of sound absorption.
Has a high thermal conductivity.
It has high strength and elasticity, which makes it easy to insulate the roof with your own hands.
Relatively low cost compared to other heaters.
The ability to shrink several times, which saves money on the transportation of glass wool.
High fire resistance as well as mold resistance.

However, many people refuse to use glass wool due to the serious disadvantages of this material.

When working with mineral wool, special equipment is required

Disadvantages of glass wool:

The need to work in special clothing, goggles, a respirator and gloves to protect the entire body from the ingress of fibers on the skin. Glass wool can cause serious irritation, so you cannot neglect safety precautions when insulating yourself with your own hands!
Low heat resistance compared to other heaters.

Basalt or stone wool

For the manufacture of basalt wool, rocks are used. The production of such insulation is very similar to the production of glass wool. The thickness of the basalt wool fibers can be from 3 to 5 microns.

Basalt wool for roof insulation

Benefits of basalt wool:

Has a high level of sound absorption.
Has a high thermal conductivity.
Compared with glass wool, it has a higher temperature resistance, does not deteriorate in the range from -180 ° C to + 700 ° C.
Strength and resistance to deformation.
Basalt wool fibers do not cause such strong irritation as when working with glass wool.

In view of these advantages, roof insulation from the inside with mineral wool is carried out using basalt or stone wool.

Disadvantages of basalt wool:

Higher price.
Due to the presence of phenol-formaldehyde resins in the binders, phenol is released at temperatures above 700 ° C. But in view of the fact that this temperature of mineral wool does not reach in use, this can hardly be attributed to serious disadvantages.

Slag wool

Previously, slag wool was often used, but now, in comparison with other heaters, only a low price remains of its advantages.

Slag wool for roof insulation

The disadvantages of slag wool include:

Low thermal conductivity.
Short service life, after 10-15 years the properties of cotton wool will be lost.
Like glass wool, the fibers are brittle, so the wool is unsafe to install.

How to install waterproofing under a warm roof

Now, let's take a look at the layers of the insulated roofing cake.

The lathing and counter-lathing are made of wood.
Vapor barrier material. If in a cold attic it was not important which insulation product to use, then here its choice should be approached more rationally. When buying a material, first of all, pay attention to its ability to withstand temperature extremes. As an example, we can cite a situation when it will be quite cold outside, but it is hot in the attic and a large temperature difference can be a serious test for a waterproofing product. Next, study its vapor permeability, if it is absent, then it will protect the thermal insulation boards from moisture well.
After laying the insulation, an additional lathing is created. It is created for an air gap, so small blocks can be used to create it.

Next comes the thermal insulation material. Since metal roofs collect moisture in the attic, it is best to use hydrophobic materials. They are not afraid of water, therefore, their service life in these conditions will be as long as possible. Foam glass and polystyrene can be considered striking representatives of this category. It is worth noting that if you cannot afford such materials, then you can use proven mineral slabs.
A waterproofing material is laid on top of the thermal insulation. It will act as a protection against precipitation and condensation.

It is worth noting that it is possible to insulate a metal roof from the inside.

But this way you will reduce the volume of the attic space and complicate the work, since the installation of thermal insulation material will become inconvenient.

How to insulate the roof so that there is no condensation

Thermal insulation begins with the installation of a waterproofing film with a slight sag perpendicular to the rafters. The joints of the material are glued with tape to eliminate gaps. After this stage, 50 mm bars are stuffed onto the rafters and a sheathing of boards is placed. In the case of insulation of the finished roof, the waterproofing film is fixed with a stapler under the rafters, gluing the joints of the film with construction tape.

Photo. Insulation of the roof of the house from the inside

It is advisable to pre-treat the rafter system with an antiseptic. Thermal insulation is placed between the rafters by a spur; slats are usually used as a rough filing. If the insulation mats are laid in several layers, then to create the desired thickness, the joints of the upper layer completely overlap with the lower row. In other words, the lower layer of insulation is offset or perpendicular to the first row.

Next, a vapor barrier film is placed, which is placed with a smooth surface towards the insulation. The rough surface of the vapor barrier retains moisture vapor, so it is laid in the direction of a warm room.If you put the vapor barrier film on the contrary, then it will not remove moisture from the thermal insulation, and condensation will form on its surface. The film is also attached with a stapler, gluing all the joints.

Next, wooden bars or a metal profile are attached to the rafters, on which the sheathing is mounted. If the finishing of this room is not provided, then you can hem the rafters with boards treated with an antiseptic. Do not forget that do-it-yourself roof insulation will save up to 25% of heat in the house, and on metal roofs it will exclude the formation of ice and condensation in winter.

Roofing material as waterproofing

For quite a long time, roofing material has been used as a waterproofing product. During this time, he underwent significant changes that only improved his performance. If the old bituminous material could lie on the roof for only 2-3 years, then the modern roofing material will lie there for about 15 years and practically nothing will happen to it.

Despite the fact that this material is used throughout the construction field, it is still not worth using it as a waterproofing product. The reason for this lies in the properties of the bitumen itself. This material does not tolerate severe frost, and it can only be arranged in cold attics. At low temperatures, the material becomes brittle and crumbles at the slightest deformation. Therefore, a bituminous roll product is used as an independent waterproofing layer only in extreme cases.

The bituminous canvas must be placed under the crate without fail. After the laying work is completed, a metal covering is arranged on top of the wooden structure. This is the only way to obtain a relatively high-quality roofing cake that can be left unrepaired for 10 years.

Alternatively, it is best to use a membrane waterproofing, or in extreme cases, a three-layer film. This material consists of polypropylene material, in which two layers perform protective functions, and the middle one plays the role of reinforcement. Thanks to the micropores of the membrane, moisture does not linger in the attic and is released naturally.

Membrane products can be used in both warm and cold roofing systems. Determination of the direction of micropores can be attributed to the difficulties in laying. If you lay it on the wrong side, then the moist air will flow from the outside, and not vice versa.

Of course, so that developers do not make mistakes, manufacturers indicate the right side in the instructions. When laying material from a roll, the top layer will be insulating, i.e. by rolling out the material, you are already laying it on the right side. If you liked the film waterproofing, then carefully read the next paragraph.

What materials are suitable for roof insulation

A lot depends on the correctly selected type of insulation for the roof, for example, how well the heat will keep in the building, whether the finish inside will remain, and so on. There are many heaters on the market today, but the most popular are:

Basalt wool - has water-repellent characteristics, does not condense and does not change its qualities during operation. It is environmentally friendly and fireproof, has excellent performance in sound and heat insulation. It is used as insulation for external and internal works on the roof. However, it needs additional vapor barrier in rooms with high humidity.

When insulating with basalt wool, it is necessary to lay a layer of vapor barrier from the side of residential premises
Expanded clay - used for insulation of different types of roofs. On flat roofs, it is laid out on the outer surface or floor slab, compacted, and then screed is made, which leads to a significant increase in the load on the entire structure.On pitched roofs with expanded clay, the ceilings of the attic floor are covered.

Expanded clay is poured into the space between the floor logs of the attic and closed on top with a vapor barrier membrane
Foamed glass - the material is resistant to deformation, water, steam, does not burn, durable, and also biologically resistant. It is used for thermal insulation of any type of roof. It has poor adhesion, therefore, during installation, it is necessary to use polymer acetate glue.

Before applying the foamed glass, the roof surface is treated with a special adhesive
Ecowool is an environmentally friendly insulation made from waste paper. Its excellent sound and heat insulation properties help to insulate the roof well. Microorganisms and various rodents do not live in ecowool, as it is treated with special bioprotective substances and fire retardants. It is an inexpensive and lightweight material. Disadvantages - the need to use special equipment during installation and special preparation for installation.

To apply a layer of ecowool, a special technique is needed.
Sawdust is breathable, clean and non-allergenic. However, it rots, is flammable, and besides that, rodents can live in it. It is used mainly for ceiling insulation and provided that the attic will not be used.

Rodents start in the sawdust, so they are rarely used and only in non-residential premises.
Izolon, penofol is a material with a porous structure, very thin (several millimeters) and very light. It is capable of reflecting up to 95% of solar energy, therefore it is used as a hydro- and heat-insulating material. Isolon is produced not only in sheets, but also in rolls.

Izolon is very easy to install and reflects heat thanks to the foil surface
Minvata is produced from dolomite, slag or other rocks using a special technology. The material is safe, its moisture resistance is low, so it is not used in rooms with high humidity (baths, saunas, steam rooms). When used in private residential buildings, mineral wool must be protected with a vapor barrier from the side of the room.

It is imperative to lay a vapor barrier on top of the mineral wool.
Polyfoam is the most popular type of insulation, since it has a low cost and is easy to install. The material is made thanks to the foaming of polystyrene, which is resistant to moisture, is simply cut with an ordinary knife, has low thermal conductivity and is easy to install. But the foam is fragile, capable of sustaining a fire and emitting toxic substances at the same time, therefore it is used mainly in non-residential premises.

Polyfoam emits harmful substances during combustion, therefore it is not recommended to use it in residential premises
Penoplex is a comfortable and strong and durable material, not susceptible to moisture and decay, has low water absorption and excellent resistance to compression. It is not subject to decomposition and is fireproof.

Penoplex does not absorb moisture and does not support combustion

The roof can also be insulated with polymeric foam materials such as polypropylene foam, polyolefin foam, foam insulation, and so on. However, they are not so common and are quite expensive.

Photo gallery: roof insulation methods

Ecowool does not allow heat and sound to pass through, and is also processed with special substances, so rodents do not live in it

Mineral wool must be protected from moisture with a layer of waterproofing

Polyurethane foam does not require a waterproofing layer and lathing for fixing the insulation

To achieve the maximum degree of thermal protection, it is necessary to insulate not only the roof, but also the overlap between the attic and the residential floor.

Sprayed insulation can be applied under the existing structure of the battens

Varieties of film waterproofing

For waterproofing roofs on outbuildings or houses with a cold type of roof, the cheapest membrane products are suitable, as for insulated ones, it is most advisable here to use the highest quality diffusion material. Of course, the price tag for such a membrane will be much higher, but this will provide you with a long operating period for the entire roofing system.

The most expensive material in the field of waterproofing is considered to be anti-condensation film. The density of this product is significantly higher than that of its counterparts. It has a rough surface, which is the reason why moisture does not accumulate on this material. Such a film is most often found on complex roofing systems, where the durability of the roof is an important parameter, even if the coating is metallic.

Anti-condensation films have a good degree of fire resistance,

and as tests have shown, it does not burn even on an open fire. Thanks to this, the material can be considered safe and used in public construction.

Why is it necessary to carry out roof insulation

The implemented project for the arrangement of roof insulation from the inside and outside allows for a high level of heat saving, which guarantees a set of practical benefits associated with various spheres of human life:

reducing the cost of purchasing energy resources required for heating or cooling premises;
effective maintenance of a normal and comfortable temperature regime in the house and prevention of heat loss;
maintaining an optimal microclimate inside the house, without excessive waterlogging and condensation.

Thanks to an integrated approach to the arrangement of the insulation system, the optimization of the use of energy resources in the cold and warm seasons is achieved, in the summer the house remains pleasantly cool, and in the winter it is always warm and cozy.

Insulation of a metal roof

Before installing thermal insulation products, it is worthwhile to understand why it is generally installed and how to make this layer effective. First of all, make sure that the plates do not come into contact with the waterproofing layer, this can lead to a complete loss of all positive qualities.

After the rafter frame is assembled, you can proceed with the waterproofing device. As a rule, it is attached to the base with a stapler and pressed against the crate. It is worth noting that if you use metal products as a coating, then the minimum distance between the insulation and the roof should be 5 millimeters. This will allow the air masses to dry the surface from excessive condensation.

In no case should waterproofing materials be stretched, otherwise it will tear very quickly during operation. When installing roll insulation, loosen the tension and let it sag by a maximum of 2 millimeters, this is quite enough.

An insulated roofing system must necessarily have high-quality natural ventilation. The clean air inlet is usually located under the eaves. The height of such a gap is made different and depends on the volume of the attic, but the minimum value is 5 centimeters.

Insulation of roof slopes with mineral wool or expanded polystyrene

For the insulation of roof slopes, already familiar materials are used - mineral wool or expanded polystyrene. It is desirable to give preference to materials based on mineral wool - they are distinguished by a higher fire safety. Note that the insulation of the roof from the inside with mineral wool is currently the most popular. If foam is still used as a heater, then it is advisable to choose extruded products that are not very good as a heat-insulating material, but do not burn at all.

Roof slopes can be equipped using different technologies, but their design always includes a heat, hydro and vapor barrier layer, as well as a counter lattice that creates a ventilation gap and is used for additional fastening of materials.

Roof mounting technology involves the following actions:

Waterproofing is laid on the assembled and installed truss system. Most often, high-density polyethylene is used as a waterproofing material, which can protect the roof from both moisture and gusty winds. The waterproofing of the roof is laid from the inside of the house with an overlap of about 20 cm and is attached to the rafters with a construction stapler.
A counter-rail is installed above the film along each rafter. This element forms a small gap between the film and the roof covering, due to which the structure is constantly ventilated.
For laying a soft roof, sheets of moisture-resistant plywood are attached above the counter-batten. Before insulating a metal roof, or a roof made of other solid roofing materials, you will need to create an ordinary crate with a well-calculated distance between its elements.
After the lathing is assembled, you can start installing the roofing.