XPS(ExtrudedPolystyrene)
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.
Standards
European and international references applicable.
Physical properties
Usage environment
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.
Documented applications
TAV. DInverted and trafficable roofs
Dry-laid above waterproofing membranes, ballasted with gravel or paved for car parks.
Basement perimeters and controterra
Perimeter insulation of basements and retaining walls in direct contact with damp soil.
Under-slab structural insulation
High-strength XPS 500/700 kPa slabs laid on the blinding concrete before pouring the structural reinforced concrete slab.
Cold storage rooms
Industrial floor insulation subject to forklift loads at sub-zero temperatures.
Compressive Resistance (kPa)
TAV. E100 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.
Used in these processes
TAV. PUsed in these systems
TAV. SReference regulations
3 norms- D.Lgs. 192/2005Implementation of Directive 2002/91/EC on the energy performance of buildingsIn force
- Dir. (UE) 2024/1275Energy Performance of Buildings - recast (EPBD)In force
- UNI EN 13501-1:2019Fire classification of construction products and building elements - Part 1: Reaction to fireIn force
Informational links to the regulatory framework. Always verify the current text on the official source.
Operational documents from this sheet
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