Thermal Insulating Plaster with Granuglass – A New Standard in Facade Systems

Exterior plaster with GRANUGLASS

Plaster containing Granuglass Expanded Glass offers a modern and eco-friendly alternative to conventional façade coatings. By using natural expanded perlite instead of recycled glass, we achieve lightweight, durable, and thermally efficient plaster for external applications.

High-Performance, Natural Mineral Filler

Unlike fillers such as Poraver, which are made from recycled glass, Granuglass is a clean mineral material that provides:

  • Stable, homogeneous plaster structure

  • Lower specific weight – easier to apply

  • Enhanced water and frost resistance

  • 100% natural origin – free from heavy metals or colorants

Applications of Granuglass-Based Plaster:

  • ETICS external thermal insulation systems

  • Passive and low-energy buildings

  • Mineral structural plasters with high breathability

  • UV- and pollution-resistant architectural facades

Benefits for Contractors and Architects:

  • Improved adhesion and elasticity

  • Naturally textured finish – perfect for color coating

  • Greater resistance to cracking and weathering

  • Compatibility with both mineral and polymer bonding systems

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Looking for a natural filler for high-performance plasters?
Granuglass Expanded Glass ensures lightweight application, durability, and long-term thermal insulation.

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Technical Specs & Availability

Recommended Granuglass grain sizes:

  • 0.25–0.5 mm (thin-coat textures)

  • 0.5–1.0 mm (thicker structural finishes)

  • Custom blends on request

Available packaging:  BIG-BAGs, bulk deliveries

 

Material characteristics of GRANUGLASS

 

The material is characterised by the following properties:

  • Physical properties of the GRANUGLASS fraction (0.5–1.0 mm)
  • Bulk density: 270 kg/m³
  • Thermal conductivity: 0.080 W/(m·K).
  • Mechanical crushing strength: 1.2 N/mm²
  • Water absorption is very low due to the closed pore structure.
  • Temperature resistance: up to +1000°C.
  • Non-flammability class: A1 (non-combustible material).

 

 

Composition of thermal insulation plaster with GRANUGLASS

 

Basic formula composition::

Component Mass share [%] Function
Portland cement 15-20 Main binder
Hydrated lime 5-10 Improved ductility
GRANUGLASS 0.5-1.0 mm 40-50 Lightweight/insulating filler
Quartz sand 0-1 mm 20-25 Carrier aggregate
Chemical additives 1-2  Property modifiersi
Water 18-22 Hydration

 

 

Detailed composition per 1 m³ of plaster:

  • Portland cement CEM I 42.5 R: 180-220 kg
  • Hydrated lime: 60-100 kg
  • GRANUGLASS fraction 0.5-1.0 mm: 450-550 kg
  • Quartz sand 0-1 mm: 200-250 kg
  • Plasticiser: 1-2 kg
  • Adhesion improver: 0.5-1 kg
  • Water: 200-250 litres

Production process

Stage 1: Preparation of raw materials

  1. Quality control of ingredients:
  • Checking the granulation of GRANUGLASS by sieving
  • Checking the moisture content of the sand (max. 3%)
  • Verification of cement activity 

      2. Weighing of ingredients:

  • Precise dosing according to the recipe
  • Weight control with an accuracy of ±2%

Stage 2: Mixing

  1. Dry mixing (2-3 minutes):
  • Cement + lime + sand
  • Homogenisation in a ribbon mixer

     2. Addition of GRANUGLASS (1-2 minutes):

  • Gentle introduction of expanded glass
  • Avoid excessively breaking up the granules

     3. Introduction of water with additives (3-5 minutes):

  • Gradual addition of water with dissolved additives
  • Mixing until homogeneous consistency is achieved

Stage 3: Quality control of the mix

  • Consistency: by Abrams cone 16-20 cm
  • Density of fresh mix: 1200-1400 kg/m³
  • Temperature: 15-25°C
  • Processing time: 2-4 hours

 

Technical parameters of the finished plaster

 

Mechanical properties:

  • Compressive strength: 2.5-4.0 MPa67
  • Flexural tensile strength: 0.8-1.2 MPa
  • Adhesion to substrate: ≥ 0.3 MPa8
  • Impact resistance: according to category I9

Thermal properties:

  • Thermal conductivity coefficient λ: 0.08-0.13 W/m-K67
  • Thermal resistance for 2 cm layer: R = 0.18-0.25 m²-K/W
  • Non-flammability class: A1 (non-combustible)10

Physical properties:

  • Density: 1100-1300 kg/m³
  • Absorbability: 8-12% by weight
  • Porosity: 35-45%
  • Frost resistance: F50-F1009

Diffusion properties:

  • Diffusion resistance coefficient μ: 8-15
  • Water vapour diffusion coefficient: 0.15-0.25×10-⁶ m²/sec.
  • Application technology

Substrate preparation:

  • Cleaning from dust, grease, old coatings9
  • Moistening of mineral substrate
  • Application of primer (optional)

Application of plaster:

  • Layer thickness: 15-30 mm in one pass10
  • Application method: manual or mechanical
  • Consumption: 16-20 kg/m² at 15 mm thickness
  • Application temperature: +5°C to +30°C

Surface treatment:

  • Levelling with an aluminium trowel
  • Smoothing with sponge or plastic float
  • Surface texture as required

Setting and curing time

  • Initial setting time: 2-4 hours
  • Final setting time: 6-8 hours
  • Curing time: 28 days
  • Maintenance: moist for the first 7 days

Modern thermal insulation plasters with GRANUGLASS

Key Technical Parameters of Mineral Plaster with

Expanded Glass GRANUGLASS (0.5–1.0 mm Fraction)

 

Parameter Typical Value / Range practical significance Source
Bulk density of GRANUGLASS aggregate 270 kg/m³ indicates the lightweight nature of the filler  
Thermal conductivity of aggregate 0.080 W/m·K determines the plaster’s insulation performance  
Aggregate crushing strength 1.2 N/mm² shows the grains resist breakage during mixing  
Dry density of hardened plaster 1.10–1.30 t/m³ 30–40% lower than traditional cement–lime renders  
Thermal conductivity λ₁₀,dry 0.08–0.13 W/m·K improves wall insulation even at 15–30 mm thickness  
Compressive strength (28 days) 2.5–4.0 MPa (CS II–III per PN-EN 998-1) sufficient for exterior render layer  
Adhesion to typical mineral substrate ≥ 0.30 MPa meets ETICS and conventional render requirements  
Water vapor diffusion resistance factor μ 8–15 maintains wall breathability and reduces condensation risk  
Water absorption (24 h) 8–12% by mass (class W₁/Wc1) ensures quick drying and minimizes efflorescence risk  
Frost resistance ≥ 50 freeze–thaw cycles (F50) stability in temperate climates  
Reaction to fire Class A1 (non-combustible) unrestricted use in fire-risk zones  
Recommended single-coat thickness 15–30 mm allows leveling and insulating the façade in one pass manufacturer’s application guidelines

 

 

Main Benefits

  1. Insulation Efficiency – λ ≈ 0.10 W/m·K can reduce the wall’s U-value by up to 25% without additional insulation boards.

  2. Lightweight – dry plaster weighs only 16–20 kg/m² at 15 mm thickness, lowering loads on walls and foundations.

  3. Fire and Frost Durability – fully mineral composition and closed-cell glass structure guarantee A1 fire classification and high frost resistance.

  4. Vapor Permeability – low μ factor ensures moisture escape, reducing biological degradation risk.

  5. ETICS Compatibility – adhesion and strength class CS II–III comply with PN-EN 998-1 for lightweight and medium-lightweight façade renders.

Application Notes

  • Dosage of expanded glass at 40–50% of the aggregate volume achieves the best balance between insulation and strength.

  • Avoid prolonged, high-intensity mixing after adding GRANUGLASS to prevent damage to the spherical grains and performance loss.

  • On low-absorbency substrates (concrete, old paints), use a bonding primer to improve adhesion and layer uniformity.

References
I. Marchewka, E. Downar-Zapolska, W. Pichór, “Thermal, mechanical and moisture properties of polymer plaster modified with lightweight fillers,” Composites Theory and Practice 22 (2022): results for mortars with 14–23 vol % expanded glass.
Primefix “Primelight R20” Technical Data Sheet 03.2025 – lightweight CS II Wc1 render with expanded glass aggregate.

Advantages of GRANUGLASS plaster:

 

  1. Thermal insulation: Significant reduction in the λ coefficient.
  2. Lightweight: Reduces structural load by 30–40%.
  3. Non-flammability: Class A1 with no toxic gas emissions
  4. Frost resistance: Closed-pore structure of GRANUGLASS.
  5. Environmentally friendly: Recycled material.
  6. Durability: Dimensional stability for decades.

Technical notes:

  1. GRANUGLASS has a closed vitreous surface, ensuring low water absorption.
  2. The 0.5–1.0 mm fraction is optimal for thermal insulation plasters.
  3. Avoid excessive mixing after adding GRANUGLASS.
  4. The material is chemically inert and does not react with cement.
  5. GRANUGLASS has a sintering temperature of 1000–1100 °C, ensuring its stability.
This modern plaster combines traditional mineral binders with an innovative thermal insulation filler to offer excellent thermal performance while maintaining the required mechanical properties.