Varieties of mineral wool and options for mounting material on various types of roofing, pros and cons of fiber-based coating, rules for choosing components, installation technology. Roof insulation with mineral wool is the creation of a shell for comprehensive protection of the house from cold, overheating, precipitation. The composition of the thermal insulation coating includes, in addition to the main element, steam and waterproofing materials, a screed to protect against mechanical stress. You can learn about the rules for forming a warming "pie" from this article.
Features of work on roof insulation with mineral wool
Mineral wool is a fibrous heat insulator made from rocks of mountain origin. The entire free space of the material is filled with inert gas, so the product has excellent insulating properties.
There are three types of mineral wool:
- Stone wool … It is made from basalt. Its fibers are short, so the panels are stiff and do not recover after compression. Blocks retain their shape under high mechanical stress and are most often used for insulating flat roofs. It is recommended to install the insulator on the roof at an early stage of construction.
- Glass wool … Made from the same materials as glass. Its fibers are long, the plates are soft, elastic, very loose. The product is superior to the stone one in terms of thermal insulation characteristics. The sheets are easily held between the rafters of the sloped roof without additional fastening. The main difference between glass wool and basalt wool is its low weight and good sound absorption. It is often used to repair heat-insulating coatings and on dilapidated structures. It costs less than basalt products.
- Slag wool … Produced from blast furnace waste. It is inferior in heat-insulating characteristics to stone and glass, but it costs much less. It is mainly used on auxiliary buildings.
When insulating a roof, mineral wool is placed between the rafters. Glass wool is elastic and able to hold on its own due to its elasticity. Basalt is more rigid, and for fastening it is necessary to mount a crate.
A rectangular insulation of various sizes or roll products with a width of 1, 2 or 0.6 m is mounted on the roof. The maximum roll length is 10 m. The thickness of the samples is selected depending on the climatic conditions of the area in which the house is located. Usually, sheets with a thickness of 150-200 mm are used. If winters are harsh, the layer should be thicker, so the panels are laid in several rows.
Mineral wool fibers repel water, but between them there are voids that quickly fill with water. If the moisture in the insulation is more than 2% of its own weight, its effectiveness will decrease by 50%. Therefore, the insulating "cake" must necessarily contain waterproofing and vapor barrier materials that protect products from moisture: they are closed on both sides with special membranes that do not allow water to pass through.
Mineral wool fibers can harm the body, they are especially dangerous for the respiratory system and eyes. Cotton wool is irritating when it comes into contact with the skin. To protect yourself, follow the simplest safety rules - work in respirators, goggles, and long-sleeved clothing. Keep this material out of the reach of children. After work, collect its remains - do not let it scatter all over the yard. Please note that of all types of insulators, glass wool is considered the most dangerous.
Advantages and disadvantages of roof insulation with mineral wool
The protective layer based on mineral fibers stands out for its excellent characteristics, due to which the insulator is often used on the roof.
The main advantages of mineral wool include the following properties:
- Does not burn or melt, does not emit toxic fumes.
- The material is quickly processed, which speeds up the installation process.
- Mineral wool of low density weighs little, it can be used to insulate the roofs of dilapidated buildings.
- The insulator protects living rooms from noise.
- Samples of various sizes can be found in the markets, which allows you to choose the best option for a particular roof.
- The material scares off mice and other rodents.
- The product is resistant to mold and mildew.
- The coating has a long service life.
- Vata does not change its qualities with temperature fluctuations.
- The product is considered a budget insulator due to its low cost.
Fibrous sheets have a number of disadvantages. These include:
- Low tensile strength.
- Mandatory use of additional materials to protect against moisture.
- The ability to absorb water, which leads to the loss of basic properties. This primarily concerns glass wool.
- It is easy to make a mistake in estimating the elasticity of the slabs. They can fall out of the frame, which will damage the integrity of the entire layer.
Roof insulation technology with mineral wool
Warming is carried out in two stages. On the first, surfaces are leveled (if work is carried out on a flat roof) or treated with protective equipment (if a pitched roof is being repaired). The preparatory work also includes the selection of the grade of the fibrous material and the determination of its thickness. Next, the heat insulator is mounted according to the selected installation method.
The choice of mineral wool for roof insulation
Mineral wool functions under extreme conditions, so only high-quality insulators can show good results. When purchasing products, use our recommendations.
During the insulation of the pitched roof, the mineral wool is placed between the rafters. In this case, the dimensions of the sheets are important. Choose the width of the glass wool blocks a few centimeters more than the distance between the beams. The products are soft and resilient and are able to stay in their original place without additional fixators. Do not mount narrow panels - gaps will increase heat loss.
It is recommended to insulate the sloped roof with sheets with a density of 75-160 kg / m3… The denser specimens are very heavy and require additional fastening. The thickness of the panels should be 1/3 less than the height of the rafters.
Standard sheets of stone wool cannot be fixed in this way. The panels do not regain their shape after compression, therefore they do not hold on their own. To fix them, fasten them to the slats from the side of the attic to the crate. For roof insulation, buy special sheets with soft edges. The special structure holds heavy specimens in the same way as glass wool.
It is recommended to lay stone wool on a flat roof, it is denser and withstands a large mechanical load. However, other types of insulator can be used if their density is more than 160 kg / m3.
If there are no slabs of estimated dimensions, buy sheets of lesser thickness and stack them in several rows. Usually, panels are mounted in this way if the estimated thickness of the coating exceeds 150 mm.
It is impossible to check the quality of the material upon purchase, but it is possible to determine the condition of the insulator if you follow our recommendations:
- Do not buy wet products. Water reduces the basic characteristics of the slabs and causes rotting of wooden beams and battens.
- Sheets must be stored in a dry place. If the product is stored outdoors, the product must be wrapped in an airtight plastic wrap.
- Buy mineral wool in company stores. In this case, the chance to buy a fake is minimal.
- Examine the product information on the label. It should contain recommendations on the use of the product, the main characteristics, the manufacturer, the date of release of the product.
- If you are on a budget, keep in mind that the price of a product is influenced by the degree of popularity of the manufacturer, the stiffness of the sheets, the type of mineral wool, and the uniformity of the density of the blocks.
- The products of German manufacturers are considered to be of the highest quality: in this country they take the certification of insulators very seriously.
Insulation of a sloped roof with mineral wool
The attic roof is insulated in two ways - by filling the gap between the rafters or by attaching cotton wool over the slats (top or bottom). The second option is considered more reliable, because in this case, the sheets form a covering that is not separated by beams. But most often the material is placed inside the frame, which reduces the operating time.
It is recommended to insulate the pitched roof during the construction of the house, together with the thermal insulation of the walls of the house. At this stage of the construction of the dwelling, the rafters can be placed taking into account the dimensions of the mineral wool and not modifying it. Make sure that the dimensions of the panels are 2-3 cm larger than the distance between the beams.
The work must be performed only in dry weather, therefore, in the fall, the roof cladding is installed first, and the insulator is placed in its regular place from the attic side. Insulation of the roof with mineral wool from the inside is also carried out in old buildings.
Let's consider in detail the method of laying the material into the frame:
- Cover the stacks and slats with a special liquid to protect them from rotting, burning, and insects.
- Measure the gaps between the beams, add 2-3 cm and trim the sheets to the required dimensions. The specimens should enter with little effort into the regular place and be fixed in this position without additional means.
- Fill all the space in the frame with mineral wool.
- Carefully inspect the coating, if any cracks are found, fill them with cotton wool scraps.
- Check that the sheets are securely fixed. If necessary, additionally fix the panels in any other way.
- Cover the wooden structure from the street side with a waterproofing film with an overlap of 15-20 cm on adjacent cuts and on the walls. Roll out the membrane from the attic floor to the skates. Do not stretch the canvas, it should hang down a little.
- Seal the joints with special adhesive tape. The sheet will retain water in the event of a roof leak, but will not impede the movement of moisture from the insulating layer, if it is present there.
- Fit the battens and counter battens under the roofing. Make sure that after the installation of the outer cladding there is a gap of 50 mm between it and the foil for ventilation.
- Install slate, shingles or other material.
- Attach a vapor barrier membrane to the rafters from below, which will protect mineral wool and wooden structures from humid air from living quarters. Lay the film with an overlap of 15-20 cm on adjacent pieces and on the walls. Do not stretch the canvas, the allowable deflection is within 1 cm. The best option for protecting the insulation from the inside of the room is a reinforced three-layer foil membrane.
- It is not necessary to cover the inside of the insulator with decorative panels.
High density slabs are heavy and will not be able to self-support between the beams. In this case, before installation, it is necessary to make a crate of rails on which they will rest.
Thermal insulation of a flat roof
Rigid mats are used to insulate a flat roof. For these purposes, stone wool is best suited, but high-density glass wool also does an excellent job. Do not use soft samples. They sag when walking on a roof, from snow or strong winds, which can lead to rupture of the vapor barrier.
In order not to disturb the waterproofing, the sheets are covered with a cement-sand screed. The additional layer increases the load on the floor, so the decision to use a screed is made depending on the strength of the structure.
The most common are two ways of insulating a flat roof with mineral wool - one-layer and two-layer. The first option involves the use of a single layer of insulator.
Work on the installation of mineral wool in one layer is performed in the following sequence:
- Clean the roof from foreign objects, dirt, old coating.
- Check that there are no gaps and depressions. If found, fill the cavities with cement mortar or putty.
- Place a long ruler against the base and make sure there are no gaps underneath. Shoot down the protruding parts.
- If uneven areas occupy a large area, fill the entire overlap with cement-sand mortar with a slope of 2-5 degrees with respect to the horizon. Wait for the surface to dry and continue working.
- Prime the surface.
- Waterproof the roof. Reinforced concrete slabs are usually protected with coating agents. The most popular substance is bituminous mastic. Wooden surfaces are covered with film materials such as thick polyethylene.
- Apply bituminous mastic to a small area of the roof and distribute it evenly over the surface. Place a sheet of rock wool on top and press down well to the base. Install the second block in the same way and press it against the first. Lay the panels with an offset in the horizontal plane so that the joints do not line up.
- On top, waterproof the insulation with roofing material and bitumen. It is not recommended to walk on such a roof, it will bend. To increase the rigidity of the coating, before laying the roofing material, the mats are covered with a layer of cement-sand screed.
A two-level roof covering is created from mineral wool of various densities. Thick sheets of low density are stacked at the bottom - 100-125 kg / m3, on top - thin samples, but more dense - 180-200 kg / m3, they are more expensive. The upper blocks should overlap the joints of the lower row. Before laying the outer panels, the bottom row is covered with bitumen mastic. Cover the insulation layer with bituminous sheets for waterproofing.
How to insulate a roof with mineral wool - watch the video:
The creation of a protective layer based on mineral wool is considered the best option for thermal insulation of the upper part of the house. To achieve a good result, little is required - to carry out the technology of installing insulation and to take work seriously.
