Closed-cell synthetic thermal insulation produced by continuous extrusion. The extrusion process creates a 100% closed-cell structure with a surface skin, conferring exceptional compressive strength and total waterproofing.
The Inverted Roof paradox. Instead of protecting the insulation from water, the XPS is positioned in direct contact with rain to protect the waterproofing membrane below.
At first glance similar to expanded polystyrene (EPS), XPS conceals a completely different production DNA. Identifiable by its bright colours (blue, pink, yellow or green), it is the material that supports the foundations of modern buildings without fearing water.
While EPS is obtained by expanding beads that join together leaving interstitial micro-voids, XPS is produced by continuous extrusion. The molten resin, mixed with a blowing gas, is forced through a die creating a structure made 100% of closed cells, externally sealed by a compact skin. This architecture physically prevents capillarity: water, even under strong hydrostatic pressure, cannot penetrate the panel.
The structural density gives XPS an exceptional compressive strength (up to 700 kPa), making it suitable beneath reinforced-concrete foundation slabs. Its closed-cell structure, however, makes it a strong vapour retarder (mu > 150): for this reason it is not recommended on breathable facades.
European and international references applicable.
XPS dissolves instantly on contact with organic solvents (acetone, paint thinners) or cold bituminous waterproofing containing solvents. Only cement mortars or specific polyurethane adhesive foams must be used for bonding.
Dry-laid above waterproofing membranes, ballasted with gravel or paved for car parks.
PRC.05 · Open the processPerimeter insulation of basements and retaining walls in direct contact with damp soil.
PRC.12 · Open the processHigh-strength XPS 500/700 kPa slabs laid on the blinding concrete before pouring the structural reinforced concrete slab.
PRC.12 · Open the processIndustrial floor insulation subject to forklift loads at sub-zero temperatures.
PRC.22 · Open the process100 kPa = approximately 10 tonnes per square metre. XPS ensures thickness (and therefore insulating power) is maintained under permanent high loads, resisting long-term compression creep. The key application: inverted roofs where the insulation is above the waterproofing membrane.
Informational links to the regulatory framework. Always verify the current text on the official source.
Specification clauses, site checklists and compliance dossiers generated from the graph — and kept in sync when a cited norm changes. Join the waiting list.
Discover Blueprint →Open the cross-material comparator with this material already selected, then add up to two more.
Compare material →