Window in ETICS termPIR® ETX — vertical section

Junction function

Window in an ETICS wall — the most common source of thermal bridges in single-family homes. The window frame has λ ≈ 0.13 W/m·K, and the typical “tightened” ETX is usually not continued around the frame = linear thermal bridge ψ ≈ 0.4 W/m·K.

Solution per the catalogue: termPIR® ETX insulating the reveal around the window frame (top, bottom, sides) with a minimum 3 cm thickness, pressed against the frame + bonded to the wall.

The vertical section shows 3 zones:

1. Above the window — ETX strip continued under the lintel (item 04); low-expansion installation foam (item 11) between the frame and the lintel.
2. External sill (item 08) — aluminium sheet or stone with a 5% slope and a 30 mm drip edge projecting beyond the render; under the sill, an EPDM waterproofing strip 200 mm wide.
3. Internal sill (item 09) — stone, conglomerate (Silestone, Caesarstone) or veneer; inserted 5 cm into a sealing mass of neutral silicone.

Critical installation aspects

• Low-expansion installation foam (item 11) — strictly low-expansion (expansion <10%); standard foam will spread the window frame and warp roller shutters. PUR Soudal Soudafoam Lowex / Hilti CF-LX.
• Reveal insulation termPIR® ETX (item 02) continued around the window frame perimeter — a strip 3–5 cm thick; without it, the bridge at the frame = condensation on the frame in winter.
• External sill (item 08) — 5% slope outwards, 30 mm drip edge projecting beyond the render line (water drained away from the façade); under the sill, an EPDM strip 200 mm bonded to the wall render mesh.
• Frame-to-ETX connection — vapour-permeable compression tape on the outside + vapour-tight tape on the inside; without this, air leakage = loss of mechanical ventilation efficiency.
• Lintel (item 04) is usually reinforced concrete → linear thermal bridge ψ ≈ 0.3 W/m·K without ETX; ETX strip across the full width of the lintel from the outside.
• Glass-to-frame bonding on the external side — neutral glazing silicone (NOT standard painter’s silicone, which degrades the EPDM frame gaskets).

Documentation

Technical Catalogue termPIR® — Residential Buildings (Gór-Stal 2022), page 37 — Two-layer ETICS wall, window detail, vertical section. Scale 1:10.

Components in this junction