GLAPOR Recycled Foam Glass Insulating Gravel is a lightweight load-bearing insulation aggregate manufactured from 100% recycled foamed glass. Designed for use beneath limecrete floors, floor slabs, foundations, and breathable floor constructions, the material combines structural support, thermal insulation, capillary break performance, and drainage within a single layer.
Unlike conventional hardcore and impermeable insulation systems, GLAPOR provides a vapour-open, moisture-resistant subfloor insulation solution particularly suited to traditional buildings, breathable floor systems, and low-energy construction. Because the material is entirely mineral and closed-cell, it does not absorb water, rot, settle, or degrade over time.
GLAPOR is widely used beneath limecrete floors in heritage retrofit projects because it allows moisture movement within the subfloor while simultaneously reducing heat loss and eliminating the need for separate hardcore and insulation layers.
Technical Data
| Property | Value |
|---|---|
| Material | 100% recycled foamed glass |
| Thermal Conductivity (λ) | Approx. 0.080 W/mK |
| Loose Bulk Density | Approx. 100–120 kg/m³ |
| Vapour Behaviour | Vapour open & capillary breaking |
| Moisture Behaviour | Waterproof closed-cell structure |
| Compressive Strength | Approx. 600 kPa nominal |
| Fire Classification | A1 Non-Combustible |
| Installation Type | Loose fill compacted aggregate |
| Typical Particle Size | Approx. 13–63 mm |
| Typical Application Depth | 150–600 mm |
Key Benefits
Insulation & Hardcore in One Layer
GLAPOR acts as both:
- a structural sub-base,
- and a thermal insulation layer,
eliminating the need for separate hardcore beneath the floor build-up.
Vapour Open & Moisture Safe
Although the glass cells themselves are waterproof, the granular structure remains vapour permeable and capillary breaking, allowing moisture movement beneath breathable floor systems without drawing moisture upward into the slab.
Load Bearing
GLAPOR is designed as a load-bearing insulating aggregate suitable for:
- limecrete floors,
- floor slabs,
- and foundation applications.
The compacted structure mechanically interlocks to create a stable insulating base layer.
Waterproof & Rot Proof
Because the material is manufactured from closed-cell foamed glass, it:
- does not absorb water,
- does not rot,
- does not support mould growth,
- and is not affected by pests or vermin.
Suitable for Breathable Floor Systems
Particularly effective beneath:
- limecrete floors,
- breathable screeds,
- suspended slab systems,
- and heritage floor retrofits.
Lightweight
Far lighter than traditional stone hardcore, helping reduce loading on sensitive ground conditions and existing structures.
Sustainable & Recycled
Manufactured from 100% recycled waste glass with low embodied carbon compared to conventional subfloor insulation systems.
Typical Applications
- Limecrete floors
- Breathable floor systems
- Heritage retrofit projects
- Ground-bearing slabs
- Foundation insulation
- Passive slab construction
- Basement floor insulation
- Lightweight fill applications
Why Use GLAPOR Foam Glass?
Traditional buildings often suffer from moisture issues where impermeable concrete slabs and membranes trap moisture within the floor structure and surrounding walls.
GLAPOR differs because the system:
- remains moisture tolerant,
- capillary breaking,
- load bearing,
- and compatible with breathable floor construction.
When combined with limecrete, the floor assembly allows moisture vapour to dissipate naturally while still significantly improving thermal performance.
Because the material is entirely mineral and closed-cell, its thermal performance remains stable even in damp ground conditions where some insulation materials can degrade or lose effectiveness over time.
Installation Overview
1. Excavation & Preparation
The floor area is excavated to the required depth and a geotextile membrane is typically installed over the prepared subgrade.
2. Placement
GLAPOR is poured directly into the excavation area as a loose-fill insulating aggregate.
3. Compaction
The material is compacted in layers using vibrating plate compactors to achieve the required density and load-bearing performance.
4. Levelling Layer
A breathable levelling layer or lime-based bedding layer is generally installed above the compacted foam glass.
5. Limecrete or Floor Build-Up
The system is then completed with:
- limecrete,
- breathable screeds,
- timber floors,
- or other vapour-open floor finishes.
A Breathable Alternative to Conventional Hardcore & PIR Subfloors
GLAPOR provides a moisture-safe alternative to:
- compacted hardcore,
- PIR subfloor insulation,
- EPS insulation,
- and impermeable concrete floor systems.
Because the system combines:
- drainage,
- insulation,
- load-bearing capability,
- and moisture safety
within a single mineral layer, it is particularly suitable for:
- traditional buildings,
- breathable floor retrofits,
- and moisture-sensitive construction projects.
