Technical Specification for External Wall Insulation Using Glass Wool Boards
The application of glass wool boards in external wall insulation systems requires strict adherence to technical standards to ensure thermal performance, fire safety, durability, and structural stability. The following outlines the standard construction practices and technical requirements for installing glass wool boards on external walls.
1. Scope of Application
Glass wool board external insulation systems are widely used in residential, commercial, and industrial buildings. They are suitable for both new construction and energy-saving renovation projects. Due to their excellent thermal insulation and fire resistance, they are particularly applicable in high-rise buildings and projects with strict fire safety requirements.
2. Material Requirements
Glass wool boards used for external wall insulation must meet the following criteria:
Density: Typically between 80–150 kg/m³, depending on design requirements
Thermal conductivity: ≤ 0.040 W/(m·K)
Fire performance: Non-combustible (Class A)
Water repellency: Hydrophobic treatment to prevent moisture absorption
Dimensional stability: No deformation under temperature and humidity changes
Auxiliary materials include adhesive mortar, mechanical anchors, fiberglass mesh, base coat mortar, and finishing coat materials. All materials must be compatible and meet relevant building standards.
3. Base Wall Preparation
Before installation, the substrate (wall surface) must be inspected and prepared:
The surface should be clean, dry, and free of dust, oil, and loose particles
Uneven areas must be leveled; deviation should not exceed specified tolerances
Cracks and defects should be repaired in advance
The wall must have sufficient bonding strength
Proper base preparation is essential to ensure strong adhesion and long-term system performance.
4. Adhesive Application and Board Installation
Glass wool boards are typically installed using a combination of adhesive bonding and mechanical fixing:
Adhesive mortar is applied using the point-frame method or full-surface method, ensuring a bonding area of at least 40%
Boards are installed from bottom to top, with staggered vertical joints
Joints between boards must be tightly fitted, without gaps
Any gaps should be filled with insulation strips of the same material
Care must be taken to maintain alignment and flatness during installation.
5. Mechanical Fixing
After initial adhesion, mechanical anchors are installed to secure the boards:
The number of anchors generally ranges from 6 to 10 per square meter, depending on building height and wind load
Anchors must penetrate into the structural wall to a sufficient depth
Fixings should be evenly distributed and installed after the adhesive has set
Mechanical fixing enhances system safety and resistance to wind pressure.
6. Reinforcement Layer Construction
A reinforced protective layer is applied over the insulation boards:
A base coat of polymer-modified mortar is applied evenly
Alkali-resistant fiberglass mesh is embedded into the wet mortar
The mesh should overlap at least 100 mm at joints
A second layer of mortar is applied to fully cover the mesh
This layer provides impact resistance and prevents cracking.
7. Finishing Layer
After the reinforcement layer has cured, the finishing system is applied:
Decorative coatings, renders, or cladding systems can be used
The finishing layer must be weather-resistant, breathable, and compatible with the insulation system
Color and texture should meet architectural design requirements
8. Construction Conditions
Ambient temperature during construction should be between 5°C and 35°C
Construction should be avoided in rain, snow, or strong winds
Direct exposure to sunlight should be minimized during installation
Adequate curing time must be ensured between each layer
9. Quality Control and Inspection
Key quality control measures include:
Inspection of material certificates and performance reports
On-site testing of adhesive strength
Verification of board alignment, flatness, and joint tightness
Checking anchor installation and mesh embedding
Final inspection of surface finish and overall system integrity
10. Safety and Fire Protection Considerations
Glass wool boards are non-combustible, but system design must comply with fire safety codes
Fire barriers may be required at floor levels or around openings
Proper sealing around windows, doors, and penetrations is essential
Workers should use protective equipment to avoid irritation from fibers
Conclusion
The successful application of glass wool boards in external wall insulation systems depends on standardized construction practices, high-quality materials, and strict quality control. By following technical specifications throughout the installation process, the system can achieve excellent thermal insulation, fire safety, and long-term durability, making it an ideal solution for modern energy-efficient buildings.
References
European Insulation Manufacturers Association (Eurima). External Thermal Insulation Composite Systems (ETICS) Guidelines.
EN 13162. Thermal insulation products for buildings – Factory made mineral wool products.
ISO 13789. Thermal performance of buildings – Transmission and ventilation heat transfer coefficients.
GB/T 25975-2018. External Thermal Insulation Systems Based on Mineral Wool.
