Perinsul, chances are you’re dealing with one of the toughest problems in modern construction: thermal bridging at structural junctions.
Traditional insulation works great in open wall cavities. But what about:
- The base of external walls?
- Floor-to-wall connections?
- Under door thresholds?
- Masonry sitting directly on foundations?
That’s where FOAMGLAS® PERINSUL HL comes in.
This 2026 comprehensive guide explains what Perinsul is, how it works, technical specifications, installation guidelines, certifications, real-world case studies, and why it’s becoming essential in high-performance building design.
1. What Is Perinsul? (FOAMGLAS® PERINSUL HL Overview)
FOAMGLAS® PERINSUL HL is a high-density, load-bearing cellular glass insulation block specifically designed to eliminate thermal bridging at structural junctions.
It’s sometimes referred to as:
- Perinsul® SIB (Structural Insulation Block)
- FOAMGLAS® structural insulation block
Unlike standard foam boards (XPS, EPS), Perinsul is not just insulation. It is engineered to function as a structural component while maintaining thermal performance.
What Makes Perinsul Unique?
Perinsul combines:
- High compressive strength
- Low thermal conductivity
- Zero water absorption
- Non-combustible performance
- Dimensional stability
- Load-bearing capacity
It effectively acts like a structural brick — but with insulation built in.
Material Composition
Perinsul is made from:
- Up to 66% recycled glass
- Natural raw materials
- Closed-cell cellular glass technology
The closed-cell structure makes it:
- Completely impermeable to water
- Resistant to mold
- Resistant to insects and rodents
- Inert and non-degrading over time
Its core mission is to eliminate the “performance gap” in buildings by maintaining thermal envelope continuity at weak structural points.
2. History and Development of Perinsul
The story of Perinsul begins with FOAMGLAS® cellular glass insulation, originally developed in 1937 by Pittsburgh Corning.
Evolution into Structural Insulation
For decades, cellular glass was used primarily in:
- Industrial applications
- Cryogenic insulation
- Roofing systems
As energy-efficient construction standards evolved in Europe during the late 20th century, a major issue emerged:
Thermal bridging at load-bearing wall junctions.
Traditional foam insulation lacked structural capacity. Masonry blocks lacked insulation.
The solution? Structural insulation blocks.
Birth of PERINSUL HL
PERINSUL HL (High Load) was developed to:
- Handle compressive demands of up to three-storey buildings
- Maintain insulation continuity
- Meet strict European building codes
Major Milestones
- 2017: FOAMGLAS® acquired by Owens Corning
- Achieved European Technical Assessment (ETA)
- CE Marking compliance
- Certified under Eurocode 6
- BBA Certification (UK)
- Euroclass A1 fire rating
As buildings shift toward net-zero and passive house standards, Perinsul fills a niche few competitors can match.
3. Technical Specifications (2026 Updated Data)
Perinsul HL is engineered for structural durability and long-term performance.
Here are the key specifications:
| Property | Value / Description | Notes |
|---|---|---|
| Material | Closed-cell cellular glass | Fully moisture-proof |
| Density | 200 kg/m³ | High structural stability |
| Compressive Strength | ≥ 2.9 MPa (2.9 N/mm²) | Supports up to 3-storey buildings |
| Thermal Conductivity (λ) | 0.068 W/mK | Effective insulation |
| Fire Rating | Euroclass A1 | Non-combustible |
| Water Absorption | 0% | No capillary action |
| Vapor Permeability | μ = ∞ | Acts as vapor barrier |
| Recycled Content | Up to 66% | Sustainable construction |
| Dimensions | 100–215 mm width | Custom options available |
Why 2.9 MPa Matters
For comparison:
- XPS insulation: ~0.7 MPa
- Standard EPS: Much lower
- Perinsul: 2.9 MPa load-bearing capacity
That’s more than 4x stronger than many foam alternatives.
Thermal Performance
With a λ-value of 0.068 W/mK, it effectively interrupts thermal bridges that account for:
20–30% of total building heat loss.
4. Features and Benefits of Perinsul
Core Features
Load-Bearing Design
Acts like a structural block while insulating.
Moisture Resistance
Closed-cell glass structure prevents water penetration.
Dimensional Stability
No shrinkage, swelling, or degradation over time.
Non-Combustible
Euroclass A1 rating — no flame retardants required.
Mortar Compatibility
Bitumen-coated surfaces enhance adhesion.
Major Benefits
1. Eliminates Thermal Bridging
Maintains continuous insulation at:
- Floor-to-wall junctions
- Masonry foundations
- Thresholds
2. Prevents Condensation
Reduces cold spots that cause:
- Mold growth
- Damp issues
- Timber decay
3. Long-Term Cost Efficiency
Higher upfront cost than foam alternatives, but:
- Zero maintenance
- No moisture degradation
- Potential for reuse
4. Sustainable Construction
Supports:
- LEED credits
- BREEAM certification
- Passive House compliance
5. Fire Safety
Non-combustible performance without chemical additives.
5. Applications of Perinsul in Modern Construction
Perinsul is designed specifically for areas where insulation continuity is structurally challenging.
Primary Applications
- Base of external walls
- Floor-to-wall junctions
- Below door/window sills
- Under sole plates (timber/steel frames)
- Parapet upstands
- Masonry veneer systems
- Basement slab interfaces
Below-Grade Performance
Unlike polystyrene products, Perinsul:
- Does not absorb groundwater
- Does not degrade in wet environments
- Remains dimensionally stable
This makes it ideal for:
- Basements
- Foundations
- Coastal builds
Heritage and Retrofit Projects
Perinsul is especially valuable in historic renovations because:
- It preserves external aesthetics
- Requires minimal visual alteration
- Enhances energy performance discreetly
6. Installation Guidelines & Real-World Case Studies
Installation Best Practices
Preparation
- Clean, level substrate
- Free from debris or ice
- No uneven foundations
Placement
- Install in a single continuous linear course
- Use full mortar bed (10–15 mm)
- Butt joints tightly
- No multi-layer stacking
Compatibility
- Works with DPM membranes
- Compatible with radon barriers
- Complies with Eurocode 6
Professional installation is recommended for structural compliance.
Case Studies
St Just, Cornwall (UK Residential)
Challenge: Severe coastal thermal bridging
Solution: Perinsul at wall bases
Result: 25% reduction in heat loss, no condensation
Bristol Performance Gap Study
Goal: Reduce discrepancy between designed vs actual energy performance
Outcome: Achieved 15–20% improved thermal rating
Oxford Heritage Retrofit
Installed in historic structure without altering appearance
Improved insulation while preserving character
Peak District National Park
Eco-sensitive construction project
Durable, fire-safe, low-maintenance solution
User Reviews (2026 Insights)
Architects and builders consistently praise:
- Moisture resistance
- Structural strength
- Fire safety
- Longevity
Common criticism:
- Higher upfront cost
- Rigid material requires level installation surface
However, in high-performance builds, professionals consider it worth the investment.
Conclusion: Is Perinsul Worth It in 2026?
If your project demands:
- Structural load-bearing insulation
- Thermal bridge elimination
- Moisture resistance
- Fire-safe construction
- Long-term durability
Then FOAMGLAS® PERINSUL HL remains one of the most advanced solutions available in 2026.
While alternatives may be cheaper upfront, few match its:
- 2.9 MPa compressive strength
- Zero water absorption
- Euroclass A1 rating
- Sustainability profile
In energy-efficient and net-zero construction, details matter.
Perinsul solves one of the most overlooked details in building performance — structural thermal bridging.
FAQs
1. What is Perinsul used for?
It is used to eliminate thermal bridging at load-bearing wall junctions and foundations.
2. Is Perinsul waterproof?
Yes. It has 0% water absorption due to its closed-cell glass structure.
3. Can Perinsul support structural loads?
Yes. It has a compressive strength of ≥ 2.9 MPa and complies with Eurocode 6.
4. Is Perinsul fire resistant?
Yes. It is classified as Euroclass A1 — fully non-combustible.
5. Is Perinsul environmentally friendly?
Yes. It contains up to 66% recycled glass and supports green building certifications.
For architects and builders focused on eliminating thermal bridges without compromising structure, Perinsul remains a leading structural insulation solution in 2026.
