6 Best Insulation Materials for Concrete Basement Walls

Concrete walls are commonly used structural materials in the construction field. They have certain quality stability, load-bearing performance, and durability. However, in terms of energy saving and heat preservation, traditional concrete walls have obvious disadvantages. Therefore, some insulation materials are usually needed to improve the thermal insulation performance of concrete walls.

This article will introduce the factors that affect the thermal insulation performance of concrete walls, the materials that can be used to improve the thermal insulation of basement concrete walls, and the techniques for concrete wall construction. This knowledge will help you decorate your house more.

Necessity of thermal insulation for concrete basement walls

Since concrete is a high-density material with poor thermal insulation performance, it will conduct low temperatures outdoors to indoors in cold seasons, causing the basement to become cold and damp. In hot seasons, the basement is also prone to condensation due to temperature differences, causing moisture and mold problems. Therefore, it is necessary to insulate the concrete basement walls.

By insulating the basement walls, not only can the basement temperature be kept stable and the living comfort be improved, but it can also effectively prevent moisture penetration, extend the service life of building materials, and ensure a healthy environment in the basement.

3 factors affecting the thermal insulation performance of concrete walls

1. Material thermal conductivity

Concrete itself has high thermal conductivity and heat energy can be easily transferred from the outer wall to the inner wall, thus affecting the thermal insulation performance of the wall.

2. Wall structure and thickness

The greater the structure and thickness of a concrete wall, the better its thermal insulation performance will generally be. This is because thicker walls can provide more insulation and reduce heat conduction.

3. External environmental factors

The thermal insulation performance of concrete walls is also affected by external environmental factors, such as external temperature, climate conditions, solar radiation, etc.

4 Ways to Improve the Thermal Insulation of Concrete Walls

To improve the thermal insulation performance of concrete walls and create a more comfortable basement space, you can take the following 4 measures to improve the thermal insulation of your basement walls.

1. Use insulation materials

Adding insulation materials such as extruded polystyrene boards, sprayed polyurethane foam, fiberglass insulation boards, rock wool (mineral wool), polystyrene foam boards, and composite insulation boards to concrete walls can effectively reduce the thermal conductivity of the wall and improve insulation performance.

2. Strengthen the sealing of the wall insulation layer

The wall insulation layer should have good sealing to prevent the exchange of cold and hot air and reduce energy loss.

‌Methods to enhance the sealing of the wall insulation layer include increasing the wall thickness, selecting wall materials with low thermal conductivity, and taking thermal insulation measures.‌

3. Choose the right wall structure and thickness

Using the right concrete wall structure and thickness can also improve its thermal insulation performance to a certain extent.

During the design and construction of the basement wall, you can choose the right wall structure and thickness according to the specific situation to achieve the ideal thermal insulation effect.

The thickness of the basement concrete wall depends on many factors, including the building's structural requirements, waterproofing requirements, whether it is a civil defense basement, etc. The thickness requirements vary according to different specifications and standards. The commonly used basement concrete wall thickness is between 140mm and 600mm.

4. Consider external environmental factors

According to different geographical locations and climatic conditions, take corresponding measures, such as increasing the thickness of insulation materials, adding waterproof layers, etc., to improve the thermal insulation performance of the wall.

6 Best Insulation Materials for Concrete Basement Walls

When choosing insulation for concrete basement walls, it’s important to consider moisture and mold resistance, durability, and thermal performance. Below are 6 common basement wall insulation materials, each with different benefits and suited to different needs and circumstances.

1. Extruded Polystyrene Board (XPS)

‌Extruded polystyrene board (XPS board)‌ is a rigid foam plastic board made of polystyrene resin as raw material, adding other raw materials and polymers, heating and mixing, injecting catalysts, and extruding and pressing.

The board has many closed bubble structures inside, with high compressive strength, good waterproof performance, chemical corrosion resistance, and strong anti-aging ability.

Features

XPS board has excellent compressive strength, low water absorption, and good thermal insulation performance. It can effectively block water vapor penetration, prevent mold from forming on the wall, and keep the temperature of the basement stable.

Applications

Commonly used as external and internal insulation in basement walls, it can be installed directly onto concrete walls and subsequently covered with a vapor barrier and plasterboard.

2. Spray Polyurethane Foam (SPF)

‌Spray polyurethane foam‌ is a heat-activated polymer that is mixed on-site with two components using special equipment. It is a thermal insulation foam.

This foam uses isocyanate and polyether as the main raw materials. It is a high-molecular polymer foamed on-site by high-pressure spraying under the action of various additives such as foaming agents, catalysts, and flame retardants.

Polyurethane foam has two types: soft foam and hard foam. The hard foam has both thermal insulation and waterproof functions. Its thermal conductivity is low, only 0.022~0.033W/(m·Κ), which is the lowest thermal conductivity among all thermal insulation materials.

Features

Spray polyurethane foam is a highly effective thermal insulation material that forms a seamless insulation layer on complex surfaces, providing excellent moisture and sound insulation.

Its closed-cell structure helps prevent water vapor penetration and provides excellent R-value (thermal performance index).

Applications

Spray polyurethane foam (SPF) is ideal for basement walls, especially those with complex shapes or difficult-to-cover areas. After spraying, the surface can be directly coated with materials such as drywall.

3. Fiberglass insulation board

Fiberglass insulation board is a board made of glass fiber as a reinforcing material through a special process.

Fiberglass insulation boards can also be customized according to specific application scenarios. For example, antistatic materials can be added to make an antistatic fiberglass board, which is used in environments that need to prevent static electricity accumulation. This board not only maintains the excellent performance of fiberglass board but also has the function of preventing static electricity accumulation and discharge.

Features

Fiberglass is a traditional and economical insulation material with good thermal insulation effect and fire resistance, but it needs to be installed with a moisture barrier to prevent moisture intrusion and is suitable for keeping the wall dry when used in basements.

Applications

Fiberglass insulation panels are typically installed between walls with wood framing and must be used in conjunction with materials such as damp-proof membranes and drywall to prevent moisture-induced mold problems.

4. Rockwool (mineral wool)

‌Rock wool (mineral wool)‌ is an inorganic fiber product made of natural rock or slag as the main raw material, which is melted at high temperatures and made by centrifugal or blowing processes.

The raw materials for producing rock wool include natural rocks such as basalt and diabase, or industrial waste residues such as metallurgical slag and fly ash.

These raw materials are melted at high temperatures, and then the melt is ejected into fibers under the action of a high-speed rotating centrifuge or blowing equipment. These fibers are solidified to form rock wool products.

The chemical components of rock wool mainly include silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, etc. These components give rock wool good chemical stability and high-temperature resistance.

In addition, to enhance the formability and performance of rock wool, a small number of binders such as phenolic resin are usually added.

The difference between rock wool and mineral wool is mainly reflected in the acidity coefficient, which refers to the ratio of the sum of the acidic oxide content to the sum of the alkaline oxide content in the product.

Generally speaking, products with an acidity coefficient greater than 1.6 are called rock wool, while mineral wool usually refers to products produced with slag as the main raw material.

Because rock wool has a larger acidity coefficient, its chemical stability and high-temperature resistance are usually better than mineral wool.

Features

Rock wool has excellent fireproof, heat-insulating, and sound-absorbing properties. It also has certain moisture-proof properties and can maintain stable performance in humid environments. It is suitable for basement areas that require additional fire protection.

Applications

Rockwool (mineral wool) is suitable for installation in the internal framing of basement walls and also needs to be used with a damp-proof membrane to ensure long-term insulation.

5. Polystyrene foam board (EPS)

Polystyrene foam board is a lightweight polymer, mainly made of polystyrene resin with a foaming agent added and heated at high temperatures.

Features

EPS foam board is another affordable insulation material with good thermal insulation performance and moisture resistance, but its compressive strength and durability are not as good as XPS board.

Applications

Polystyrene foam boards can be used for interior and exterior insulation of basement walls and require a vapor barrier to be added during installation to improve performance.

6. Composite insulation board

‌A composite insulation board‌ is an insulation board made of multiple materials, mainly composed of two parts: the base layer and the insulation layer.

The base layer usually uses inorganic materials such as high-strength cement and gypsum to ensure the basic strength of the board; the insulation layer uses high-efficiency insulation materials such as polystyrene foam, rock wool, phenolic resin, etc. with low thermal conductivity to ensure good insulation effect of the board.

Features

Composite insulation board is composed of a layer of high-efficiency insulation material (such as XPS, EPS, or mineral wool) compounded with gypsum board or other decorative board materials, providing integrated insulation and decorative effects and simplifying the construction process.

Applications

Composite insulation panels are particularly suitable for use in basement walls, providing a quick and easy insulation and decorative solution.

Basement Wall Insulation Selection Guide

When choosing basement wall insulation materials, consider the basement's humidity level, local climate conditions, and project budget.

If the basement is severely damp, materials with good moisture-proof properties, such as XPS board or spray polyurethane foam, are preferred. For an economical solution, fiberglass combined with a moisture-proof membrane is also a good choice.

Concrete wall construction technology

During the construction of concrete walls, the following key technologies need to be noted:

1. Concrete pouring technology

When pouring concrete walls, it is necessary to ensure the quality and uniformity of the concrete to avoid problems such as cracks.

At the same time, control the appropriate pouring temperature and humidity to improve the density and strength of the concrete wall.

2. Accurate wall size control

The wall size control must be accurate to ensure that the thickness of each wall is uniform to achieve a better insulation effect.

3. Coordination of construction processes

Concrete wall construction needs to be coordinated with other processes, such as floor construction and roof construction, to ensure the flatness and coordination of each construction link to avoid affecting thermal insulation performance.

4. Wall anti-leakage

During the construction process, attention should be paid to the anti-leakage treatment of the wall, such as choosing a suitable waterproof coating or installing a waterproof layer to prevent water from penetrating and affecting the thermal insulation performance of the wall.

Conclusion

In summary, the thermal insulation performance of concrete walls is closely related to construction technology. The thermal insulation performance of basement concrete walls can be effectively improved by selecting appropriate thermal insulation materials, strengthening the sealing of walls, rationally designing wall structures and thicknesses, and paying attention to key technologies during construction.