EPS—ExpandedPolystyrene
The world's most widely used insulator (commonly known as polystyrene foam). Made 98% of still air trapped in closed spheres of sintered expanded polystyrene. Offers excellent thermal performance, negligible weight and unbeatable cost, making it the undisputed core of residential ETICS external insulation systems.
ETICS/EIFS wall stratigraphy. EPS acts as a thermal jumper bonded to the outside of the wall. It is incompressible but extremely fragile on the surface: mesh reinforcement with fibreglass is mandatory.
Sintered Expanded Polystyrene (EPS) has democratised energy efficiency. It is the backbone of building renovation (Superbonus), enabling the entire building to be wrapped in a continuous thermal layer that eliminates thermal bridges at a fraction of the cost of other insulators.
Via high-temperature steam injection and a blowing agent (pentane), polystyrene beads expand up to 50 times their original volume. In a closed mould, a second steam burst permanently fuses the bead edges (sintering), creating a block of a billion microscopic closed cells. These cells trap air, stopping convective movement: EPS becomes a masterful insulator while being 98% air and only 2% actual plastic material.
Unlike totally closed-cell polyurethanes, standard white EPS maintains reasonable vapour permeability (mu 30 to 70), similar to dense wood. Its main limitation is UV sensitivity (left raw in sunlight it yellows and crumbles to dust in months) and instant dissolution in contact with chemical solvents.
Standards
European and international references applicable.
Physical properties
Usage environment
GREY EPS: do not leave exposed to direct sun without shade netting before rendering. The graphite overheats (>80 degrees C) causing panel warping (U-shape bowing) that will violently debond from the wall. SOLVENTS: a spray of nitro thinner dissolves an entire block instantly. On site, prohibit any solvent-based paint or adhesive nearby.
Documented applications
TAV. DExternal Wall Insulation (ETICS/EIFS)
Panels bonded externally to the masonry, mechanically fixed, and rendered with fibreglass mesh and siloxane finishing coat.
Cavity Wall Insulation
Insertion of panels or injection of loose beads into the air gap of historic double-leaf perimeter walls.
Loft and Slab Insulation
Panels laid on top of the last uninhabitable floor slab. Cost-effective solution to prevent heat loss upwards.
Structural Lightening (Geofoam)
Large blocks laid under road ramps or embankments to avoid settlement of marshy ground (weighs 1% of soil).
Thickness Needed to Achieve U = 0.20 W/m2K
TAV. EWhite EPS continues to dominate the external insulation market for three reasons: it costs less than half the alternatives, is hot-wire cut on site with millimetric precision, and is dimensionally stable over time without persistent chemical emissions.
Used in these systems
TAV. SOperational documents from this sheet
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 →Compare with other materials
Open the cross-material comparator with this material already selected, then add up to two more.
Compare material →