Do you notice that no matter how you turn on the stove, it’s cold in the house? The solution to the problem will be the insulation of the roof using the right materials. I will talk about what materials can be used for thermal insulation of various types of roofs. In the end, you can decide what is right for your home.
What you need to know about roof insulation
When choosing the best roof insulation, you need to decide on the type of roofing system and only after that decide which option is suitable and which is not. At the moment, flat and pitched (inclined) roofs are relevant.
On each of the listed systems, thermal insulation behaves differently, and therefore it is necessary to consider the advantages and disadvantages of materials in relation to the roofs on which they will be used.
| Name of insulation | Thermal conductivity (W/m °C) | Density (kg/m³) | Water absorption (%) |
| Extruded polystyrene foam | 0,034 | 38.40 | from 0.4 |
| Expanded polystyrene of low density (polystyrene) PSB-S 15 | 0,043 | 15 | 1 |
| Sprayed polyurethane foam | 0,027 | from 14 to 80 | 0,5 |
| Penoizol | from 0.028 to 0.047 | up to 75 | up to 20 |
| Mineral wool | from 0.039 to 0.043 | 160 | 1,3 |
| Expanded clay backfill | 0,09 | non-static | 0,5 |
| Expanded clay concrete screed | 0,140 | 500 | 10 |
| Ecowool | 0,042 | 28-60 | up to 20 |
| Sawdust | no more than 0.093 | 230 (bulk density) | up to 20 |
The table lists those characteristics of materials that determine their suitability as roofing thermal insulation.
Overview of thermal insulation for flat roofs
Flat roofs are of two types:
- Exploited;
- Unexploited.
The difference between the two varieties is that you can go to the operated roofs, while non-operated structures are not designed for this. This means that a different mechanical load will be applied to the insulation laid with your own hands on different types of roofs, and this must be taken into account when choosing thermal insulation.
| Illustrations | Description of materials |
 | Extruded polystyrene foam. Such insulation in the domestic market is represented by products of the Penoplex and TechnoNIKOL brands. The heat-insulating material is a plate with a flat or curly edge.
The most common sizes of plates: thickness - from 20 to 100 mm, width and length 0.6 × 1.2 m. Properly selected extruded polystyrene foam is so strong that it can be used to insulate exploited roofs. To do this, paving slabs or a special geomembrane with soil backfill are laid on top. |
 | Low density expanded polystyrene (polystyrene). Styrofoam can be used as a substitute for extruded polystyrene foam, but only on unused roofs.
Foam boards will provide low thermal conductivity, but the density of the material is low. To move along the insulated roof, it will be possible to use wide walkways knocked together from boards. Why is polystyrene used as insulation for roofs if the plates are afraid of mechanical stress? It's simple - the price of the material is affordable and this is relevant if, with a limited budget, you need to insulate a roof with a large area. |
 | Sprayed polyurethane foam. Two-component polyurethane foam (PPU) has been used as a roofing insulation for the last ten years.
The insulation is characterized by excellent adhesion to various materials, and therefore can be sprayed both on pre-prepared surfaces and on the old roofing. The sprayed polyurethane foam during polymerization increases in volume several times and provides thermal conductivity, as low as that of expanded polystyrene. PPU spraying can be used as a finishing layer, that is, there is no need to apply additional roofing coatings. |
 | Mineral (stone) wool.
The instruction for insulation of non-exploited roofs provides for the use of stone wool slabs with a density of 120-160 kg / m³. If the exploited roof is insulated, plates with a density of 160 kg / m³ are used. Which minvata is better? The brand does not matter, since the characteristics of the material depend only on the density of the boards. The higher the density, the better. How to choose mineral wool? For the convenience of work, you need to buy plates with a thickness of 50-100 mm. In addition, you need to choose plates for the roof that you are going to insulate. For example, the ROCKWOOL brand for flat roofing produces a product line - "RUF BATTS". Stone wool slabs are laid on a pre-laid waterproofing, and a cement-sand screed with wire reinforcement is laid on top of them, or a continuous sheathing of slab materials for subsequent roll coatings. |
 | Expanded clay backfill - cheap, lightweight and at the same time durable insulation.
Expanded clay is poured as a continuous layer on a flat roof and a thin reinforced cement-sand screed is laid on top of it. Due to its low weight, expanded clay backfill is the best option if you need to insulate the roof in an old house. |
 | Expanded clay concrete screed - excellent thermal insulation, which is characterized by low weight and high strength.
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Overview of thermal insulation for pitched roofs
| Illustrations | Type of sloping roof according to the method of insulation |
 | Warm. In such structures, slopes are insulated, due to which the attic space will be warm and can be used for living. |
 | Cold. In such structures, the slopes are not insulated, and thermal insulation is laid out or applied to the ceiling from the side of the attic. Such a scheme does not provide for the use of an attic space for living. |
| Illustrations | Thermal insulation for a warm roof |
 | Mineral wool. Mineral wool slabs are laid in the gap between the rafters, with the bottom side on the crate.
To ensure low thermal conductivity of the slope, the insulation layer in the roofing cake should be at least 150 mm. Mineral wool is characterized by high moisture absorption. Therefore, the insulation is protected from the attic with a vapor barrier film, and from above - with a vapor diffusion membrane.
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 | Styrofoam. This material is good for zero moisture absorption, so it does not need to be protected with vapor and waterproofing. The foam layer in the truss system should be 150-200 mm. There are no requirements for the density of the material, since it will not be affected by mechanical loads. |
 | Polyurethane foam spraying. Two-component polyurethane foam (PPU) is applied to the crate of the truss system from the inside of the attic or outside the slope.
Insulation completely envelops the wood and, increasing in volume at times, reduces the thermal conductivity of the roof.
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| Illustrations | Thermal insulation for cold roofs |
 | Ecowool. This insulation is made from recycled paper, antiseptic additives and flame retardants. As a result, ecowool does not rot and is characterized by moderate flammability.
Ecowool is applied to the ceiling manually or mechanically. Machine application allows you to achieve maximum layer density. |
 | Sawdust. To use sawdust as a heater, they are mixed with lime. The addition of lime prevents the material from rotting.
The advantage of sawdust is its low price. But there are much more disadvantages - rodents nest in sawdust, sawdust absorbs moisture, sawdust burns. |
 | Expanded clay backfill. Expanded clay is poured into the gap between the lag, flush with their surface. If you plan to make the attic exploitable, on top of the expanded clay backfill, you can fill the crate along the logs.
Expanded clay absorbs moisture, so before laying it, you need to lay a vapor barrier on the ceiling. |
 | Styrofoam. This insulation on the floor can be laid in the form of plates or covered in the form of granules. Plates have a higher density than granules, but their junction with the logs must be treated with mounting foam.
If granules are poured, a crate must be filled over the lag, which will press the insulation. |
 | Mineral wool. This insulation is laid between the lag on the vapor barrier in 2-3 layers, so that the total thickness is 150-200 mm.
As an alternative, latex wool is suitable - a more modern insulation with zero phenol content. |
 | polyurethane foam. PPU is sprayed over the entire ceiling in several layers so that the thickness of the insulation after polymerization is 200 mm. |
 | Penoizol. Penoizol is sprayed in the same way as PPU. But, due to the environmental safety of the material, you can work with it without a respirator. |
Summing up
Now you know how you can insulate different roofs. Each material is good in its own way, you need to choose depending on the operating conditions and technical parameters of the roof. I also recommend watching the video in this article, I'm sure you will be interested.
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