Rock wool is widely used in various engineering projects due to its excellent fire resistance, thermal conductivity, and stability in building energy conservation, industrial insulation, HVAC ductwork, and structural fire protection.

Different usage scenarios, temperature levels, and energy-saving standards have different requirements for rock wool thickness. Therefore, correctly selecting the rock wool thickness is a crucial step in ensuring energy conservation, fire resistance, and long-term performance.

This article will provide a clear and actionable guide to selecting rock wool thickness from multiple perspectives, including engineering applications, regulatory requirements, and thermal calculation logic, helping you quickly determine the appropriate specifications.

I. Why is Rock Wool Thickness Important?

The impact of rock wool thickness on engineering performance is mainly reflected in the following three aspects:

1. Thermal Insulation Performance

The main function of rock wool is to reduce heat loss; therefore, the greater the thickness, the stronger the insulation capacity. In cold northern regions or buildings requiring high energy efficiency, the thickness will be increased accordingly.

2. Fire Resistance and Thermal Insulation

Rock wool is a Class A non-combustible material. In scenarios such as steel structure fire protection and exterior curtain walls, increasing the thickness can effectively extend the temperature transfer time and improve the fire resistance limit. 3. Sound Absorption and Insulation

In environments such as computer rooms, air ducts, and factories, the greater the thickness of the rock wool, the more significant its sound absorption capacity, especially effective against low-frequency noise.

In short, thickness determines the main performance of rock wool in a project and is a fundamental parameter for selection.

Rock Wool Board

II. Recommended Rock Wool Thickness for Common Scenarios (Long-tail keyword layout: exterior wall rock wool thickness, air duct rock wool thickness)

Below are recommended thicknesses for different scenarios based on engineering applications, which can serve as a reference for selection.

1. Exterior Wall Insulation Rock Wool (Recommended Thickness: 50mm–100mm)

The thickness of exterior wall rock wool is usually affected by national building energy efficiency standards. Common choices are:

50mm rock wool board: Suitable for lower energy efficiency requirements or southern regions;

80mm rock wool board: The most common thickness for residential and commercial buildings in China;

100mm rock wool board: Frequently used in cold northern regions or high-energy-efficiency projects.

In exterior wall systems, the thickness of rock wool is typically selected in conjunction with its thermal conductivity and density to avoid simply increasing its thickness without meeting operational requirements.

2. Fire-resistant Rock Wool for Steel Structures (Recommended Thickness: 40mm–120mm)

The required rock wool thickness varies depending on the fire resistance rating of the steel structure:

Fire resistance rating requirement: 0.5h, Rock wool fireproof thickness: approximately 40mm

Fire resistance rating requirement: 1.0h, Rock wool fireproof thickness: 60–80mm

Fire resistance rating requirement: 1.5h, Rock wool fireproof thickness: 80–100mm

Fire resistance rating requirement: 2.0h, Rock wool fireproof thickness: 100–120mm

3. Duct Insulation Rock Wool (Recommended Thickness: 25mm–50mm)

Duct rock wool is mainly used to reduce heat loss and provides sound absorption:

25mm: Commonly used in air conditioning supply ducts;

30–40mm: Widely used in ventilation ducts and exhaust systems;

50mm: More suitable for chilled water pipes or systems with large temperature differences.

Dual-duct space is limited, therefore, the thickness selection focuses on practicality and ease of construction. 4. Industrial Pipeline Rock Wool (Recommended Thickness: 30mm–80mm)

The thickness of industrial pipeline rock wool mainly depends on the medium temperature:

Pipeline medium temperature: 0–100°C

Recommended rock wool thickness: 30–40mm |

Pipeline medium temperature: 100–200°C

Recommended rock wool thickness: 40–60mm |

Pipeline medium temperature: Above 200°C

Recommended rock wool thickness: 60–80mm and above

The higher the temperature and the longer the transport route, the greater the required thickness.

5. Sound Insulation and Absorption Rock Wool (Recommended Thickness: 50mm–100mm)

Used in recording studios, machine rooms, equipment rooms, etc.:

50mm: Basic sound-absorbing wall surface;

75mm: Machine rooms, structural sound absorption in commercial spaces;

100mm: Large factories, high-noise areas.

The higher the thickness, the more obvious the sound absorption effect.

III. Considerations for Rock Wool Thickness Selection (Long-tail keyword: Rock Wool Thickness Selection)

When selecting rock wool thickness for a project, consider not only the application scenario but also the following key factors:

1. Density Affects Structural Strength and Usage Scenarios

Higher density results in higher structural stability.

For example:

Exterior walls commonly use 80–120 kg/m³

Air ducts commonly use 40–60 kg/m³

Even with increased thickness, low-density rock wool cannot meet the weather resistance requirements of exterior walls.

2. Energy-Saving Requirements Determine the Final Thickness

Different provinces have different building energy-saving standards. Exterior wall thickness is usually directly related to energy-saving design calculations and should not be arbitrarily reduced.

3. Thicker is Not Always Better

Excessive thickness may lead to:

Increased construction difficulty;

Upgraded fixing methods;

Higher costs with less noticeable results;

Insufficient space for air ducts.

A reasonable thickness is the balance between cost and effectiveness.

IV. How to Quickly Determine the Right Rock Wool Thickness for Your Needs?

If you are unsure about the appropriate rock wool thickness, you can refer to the following methods:

1. First, consider the project type (exterior wall, air duct, pipeline, fireproofing)

2. Then, consider the operating temperature or energy-saving requirements

3. Combine density and construction method to determine the final thickness

If you can provide detailed project parameters, such as the usage environment, area, and structural form, Yutsen can provide clear advice within minutes.

V. Summary: There is no standard answer to rock wool thickness selection, but there are standard methods.

The selection of rock wool thickness always revolves around three core principles:

Meeting energy-saving and temperature control requirements

Meeting fire protection specifications

Meeting construction and structural conditions

By comparing scenarios, analyzing parameters, and adhering to specifications, you can easily select the appropriate thickness to ensure the project's performance and durability.