Thermal insulation of the roof: select the insulation and calculate its thickness

The roof is a major component in maintaining the comfort and energy efficiency of your house. Not only does proper thermal insulation lower energy costs, but it also aids in maintaining a comfortable interior temperature. Crucial elements in this process are determining the appropriate insulation’s thickness and making that choice.

The efficiency of insulation materials varies, as does their suitability for various climates and roof types. Your decision should be guided by elements like durability, environmental impact, and R-value (thermal resistance). By being aware of these factors, you can make sure the insulation you choose fits your requirements.

When calculating insulation thickness, it’s important to take into account things like building codes, the intended energy efficiency, and the local climate. Although thicker insulation often performs better thermally, cost and effectiveness must be carefully considered.

This article will examine different types of roof-compatible insulation, go over how to measure your insulation’s thickness, and offer helpful advice on how to insulate your roof properly to improve your home’s energy efficiency.

Which insulation to choose

The construction market offers a wide range of thermal insulation materials, and it’s not always clear which is best to select. We will discuss the most well-liked of them to help you make up your mind. Among them are:

  • Mineral (stone) cotton wool.
  • Mineral cotton wool based on quartz melt.
  • Foam polystyrene.
  • Extruded polystyrene foam.
  • Poliuretan foam.

We’ll talk more about these materials’ composition, benefits, and drawbacks later.

Mineral (stone) cotton wool

In a specialized oven, basalt is melted to create stone cotton wool. It’s commonly referred to as basalt in this context. Melted stone is formed into thin threads, which are then connected and baked at 200°C. Insulation plates are formed by cutting hardened material.

The main advantage of stone cotton wool is low thermal conductivity. The lower it is, the better the material holds the heat in the house. Thermal conductivity of stone cotton wool – only 0.035-0.042 W/(m · K). This is a very good indicator. For example, 200 mm of such insulation holds heat as reliable as the concrete wall 3.5 meters thick. Other advantages of stone cotton wool include its high vapor permeability and low hygroscopicity. This means that it passes wet air well and does not get wet. It is important to note that the gravity class of stone cotton wool is NG. This means that it does not burn and does not contribute to the spread of a fire.

Mineral cotton wool based on quartz melt

While mineral wool derived from a quartz melt resembles stone in appearance, it is not the same composition. Such cotton wool is manufactured from processed glass, limestone, and quartz sand. At very high temperatures, these components melt and become woven into the fibers. Then they are cool and connected. The material obtained is formed into rolls or plates.

Quartz wool has a thermal conductivity of 0.038–0.046 W/(m · K), which is the same as that of stone. Similar to basalt insulation, quartz melt material "breathes" well and doesn’t get wet in damp air. He does not distinguish between toxic substances and does not burn. The two are different in that quartz wool is typically made in rolls and has a higher degree of elasticity. Typically, stone cotton wool is formed into plates.

Polistyle foam (PPS)

The process of steaming involves placing microgranules of polymer material in a form and reacting them with water vapor. This creates polystyrene foam. This causes the granules to enlarge and fill with air. Because air bubbles cannot transfer thermal energy, polystyrene foam has a low thermal conductivity of 0.037–0.042 W/(m · K).

The benefits of polystyrene foam include its low weight, affordable price, and resistance to moisture in addition to its good thermal insulation qualities. Significant drawback: vapor permeability is nearly nonexistent. This implies that mold and moisture may grow on the interior décor of a building if the polystyrene foam insulation beneath the roof is not properly arranged. The fueling of polystyrene is another drawback. Such material is easily ignited and simultaneously emits toxic substances because it is a member of the G3 combination group.

Extruded polystyrene foam (EPPS)

Such insulation has a low weight and looks similar to polystyrene foam. The method used for EPS is extrusion, which involves mixing foaming agents with high-pressure polystyrene granules before they are squeezed out of the extruder. Because of this, EPPS has a stronger structure and is more densely packed.

The benefits of extruded polystyrene foam include a ten-fold improvement in resistance to wetting over regular polystyrene foam and a low thermal conductivity of 0.029 W/(m · K). High combustibility and low vapor permeability are drawbacks. Because EPS doesn’t pass steam, mold could grow on the roof’s interior cladding. Extruded polystyrene foam falls into class G4 for combustibility. This indicates that he burns well and simultaneously releases harmful substances, just like regular polystyrene foam.

Poliuretan foam

A foamy combination of polyol (multi-tower alcohol) and polyisostal (hydroxyl) is known as polyurethane foam. This type of insulation is made in cylinders and sprayed on with a sprayer while the roof is being warmed.

One of polyurethane foam’s primary benefits is its incredibly low thermal conductivity, which ranges from 0.019 to 0.035 W/(m · K). Furthermore, it seals even the tiniest cracks when applied, guaranteeing the roof’s dependable thermal insulation. It does not distinguish between harmful substances and has a high resistance to moisture. Polyurethane foams share the same shortcomings as PPS and EPS: they have low vapor permeability and are flammable (G3).

Its thickness can be computed by selecting a heater for the roof and determining its thermal conductivity. We’ll talk about how to accomplish this later.

We look at important factors to take into account when choosing and calculating the thickness of insulation for your roof in the article "Thermal insulation of the roof." A number of considerations must be made when selecting insulation, including material type, R-value (thermal resistance), and climate suitability. Knowing how to calculate the thickness of insulation in your home will guarantee maximum comfort and energy efficiency. In order to assist you in making wise choices and guarantee that your roof properly conserves energy in addition to providing protection, we delve into realistic approaches and factors.

How to calculate the thickness of the insulation

It is important to clarify that when we discuss the thickness of the roof heater, we are referring to the overall thickness of all of its layers. Such a thickness is contingent upon two numbers:

  • The ability of roofing to resist heat transfer. It depends on the location of the house. Heat transfer resistance in your city can be found in the table below.

  • The heat conductivity of the insulation. We talked about this indicator earlier. Each insulation has its own thermal conductivity, so we give all values ​​in one table.

This holds true for stone cotton wool as well as other heaters in slabs and rolls, such as polystyrene foam, extruded polystyrene foam, and mineral wool made from quartz melt.

Factors to Consider Guidance
Insulation Type Choose based on climate and budget. Common types include fiberglass, foam board, and spray foam.
R-Value Determine the required thermal resistance. Higher R-value provides better insulation.
Roof Structure Consider thickness constraints. Ensure insulation doesn"t compress in confined spaces.
Vapor Barrier Essential to prevent moisture buildup. Install on the warm side of insulation.

Maintaining comfort and energy efficiency in your home depends on the insulation you choose for your roof. You can make an informed choice if you are aware of the insulation qualities and the climate where you live.

Assessing the R-value required for your area should come first. The effectiveness of the insulation in preventing heat flow is indicated by this value. R-values may need to be higher in colder climates and lower in warmer ones.

Next, think about the kind of insulation that will work best for your budget and roof structure. There are advantages and disadvantages to rigid foam boards, fiberglass, and spray foam in terms of price, ease of installation, and functionality.

In order to determine the appropriate thickness of insulation, you must weigh the available space in your roof structure against the desired R-value. In doing so, sufficient thermal resistance is guaranteed without sacrificing headroom or ventilation.

To maximize the effectiveness of insulation, proper installation is essential. Make sure all openings are closed and insulation is spread equally to avoid heat loss or moisture accumulation, which over time can cause damage and decreased effectiveness.

The performance of your roof insulation can be maintained over time by routinely checking it and making any necessary adjustments. As technology develops, take into account updates or modifications to lessen your impact on the environment and increase energy efficiency.

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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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