Insulation of flat roofs is carried out according to the canons, which are noticeably different from the thermal insulation of pitched roofs. In flat versions, there are no parts of the rafter system, so the installation must be carried out according to a different principle. Before work, it is necessary to study the requirements for the quality of thermal insulation materials and decide on the type of roof device.
Requirements for materials for thermal insulation
It is advisable to insulate a flat roof using materials with low thermal conductivity. When choosing any insulation for the roof, it is necessary to take into account that the period of its operation will depend on many reasons, including temperature and humidity conditions, diffuse and capillary humidification, mechanical influences. A good heat insulator must retain its properties for a long time, remain moisture resistant and environmentally friendly, maintain resistance to chemical and biological components, and also comply with fire and sanitary standards.
A good insulation for a flat roof must be extremely durable, have the required level of resistance to tearing and compression, not delaminate or change the structure. Before purchasing materials, you should first of all get acquainted with the accompanying documentation for them and buy thermal insulation, the quality of which is confirmed by all the necessary certificates.
Roofing options
A flat roof can be installed in two versions: operational and non-operational. Each of them has its own characteristic features regarding installation.
Operational
Installation of operational type roof insulation is carried out taking into account that the roof will be used daily throughout the year, for example, as a terrace. Such a roof can be inverted or classical, the difference between them lies in the location of the roof insulation layer. In the first case, it will be located under the waterproofing layer, in the second - above it.
When installing the operational option, a special screed or reinforced concrete floor is laid under the waterproofing. This procedure is carried out so that the roof can withstand heavy loads that are unevenly distributed over its surface. A maintenance roof will be more expensive.
Not operational
A non-operational roof does not need additional maintenance, since it is used only for its intended purpose as a roof. It is not designed for loads other than snow, so it does not need a rigid base under the waterproofing layer. The cost of this option will be lower, but the service life, wear resistance, durability and strength are less compared to a service roof.
Types of thermal insulation
A flat roof device with any insulation can be single-layer or consist of two layers.The technology and installation methods for both options are the same in basic parameters, but also have some differences.
Single layer
This scheme is widely used during the repair or construction of garages, warehouses or industrial buildings from scratch. One-layer technology is used to mount insulation for a soft roof under the screed, as well as options for other purposes. The insulation layer must be made of a material of uniform density. If the roof is in use, it is additionally covered with a concrete screed.
Double layer
For new buildings, a two-layer scheme is most often used when installing a thermal insulation system. It consists of two levels: lower and upper. The material used at the bottom is considered basic and must have a thickness of 70-170 mm in combination with the ultimate thermal resistance. Thanks to the top layer, the load is evenly transferred to the flat system. Its material is noticeably thinner than the lower one - the thickness is no more than 30-50 mm. Thanks to this redistribution, the weight of the insulation and the entire system is noticeably reduced.
Vapor barrier value
Areas that are in active contact with cold and warm air from inside the building must be protected from steam, as they are designed to separate cold and warm zones. Due to excessive moisture in the inner parts of the roofing material, the structure can begin to rot, mold mass, fungi and corrosion of metal elements form in it.
To prevent steam from entering the thermal insulation layer and the accumulation of water inside the material and structures, a vapor barrier or a vapor barrier is used. It is a variety of films and materials that protect the thermal insulation and roof structure.
Materials for insulating a flat roof
Insulation for hard or soft roofs can be different. Materials are used that differ from each other in their qualities, installation options and prices.
Expanded clay
Expanded clay is considered one of the cheapest and most affordable options, like polystyrene or expanded polystyrene. With its help, it is not so easy to level the surface and make a smooth slope, as well as achieve a uniform screed thickness for the entire roof plane. Working with such material can increase construction costs and duration.
Perlite sand
Perlite sand is also an affordable option for insulation, it is a fairly budget material. It is not able to compete with modern polymer parts and fiber-based insulation. Sand is also not easy to level the roof surface, in addition to this, it will need additional protection from external influences.
Mineral wool
Mineral wool is often used to insulate the outside of the roof. Since it is not strong enough, an additional screed is used to strengthen it. Due to the prefabricated or wet screed, the load will be evenly distributed, the roof surface will become solid and will have the required rigidity. Experts advise choosing the strongest slabs made from basalt rocks.
Basalt fiber
Insulating the roof with rigid basalt fiber slabs is for those who want to maximize the life of the roof. Plates do not cause difficulties during the installation process, are distinguished by optimal heat-insulating properties and have an increased level of fire safety. Their main disadvantage is increased hygroscopicity. If the layer is damaged and cracks form in it, moisture will begin to penetrate inside. In the process of getting wet, the basalt insulation for the roof will lose its basic properties.
Foam glass
Foam glass is resistant to high temperatures, increased strength, resistance to ultraviolet rays.It does not corrode, retains its shape for a long time due to a reduced coefficient of expansion due to high temperatures, and also has the longest possible service life. The main disadvantage of foam glass is its high price.
The nuances of fixing insulation on a flat roof
Regardless of the choice of material, you need to firmly fix it on the base. To do this, you can apply one of two available methods:
- Bonding on bitumen. This is a rather expensive and complicated process, it is worth choosing it if you have a concrete base, so as not to purchase expensive dowels additionally.
- Mechanical method based on dowels. These elements are equipped with wide caps, with the help of which the fasteners do not pass through the waterproofing surface and do not affect the tightness of the roof.
According to the construction rules, the waterproofing carpet is attached to the insulation in the same way with which it was fixed to the base. If the insulation consists of two layers, the slabs are laid out "in a razbezbezh", the joints of the lower tiles should cover the upper ones. Compliance with this rule makes it possible to avoid the formation of "cold bridges". To fix all the plates, at least two dowels are used.
If the elements are mechanically fixed, it is recommended to use polymer-bitumen materials as vapor insulation. Due to their elasticity, the holes will be tightened evenly.
