Plinth — 2-layer basement wall — termPIR® WS

Junction function

Plinth of a 2-layer basement wall — economy standard for a typical single-family house. In contrast to the three-layer variant, the termPIR® insulation is placed directly on the external face of the basement wall, protected only by a dimpled membrane.

Choose the 2-layer variant when:

• The soil is permeable (sands, gravels) — water drains freely into the drainage system.
• There is no permanent water pressure — groundwater level below the foundation base (difference > 30 cm).
• Cost matters — 30–40% cheaper than the 3-layer variant.

Typical user: a new single-family house with a garage or technical basement.

Critical installation aspects

• termPIR® WS (item 07) — glass veil facing on both sides (grey colour) is bonded directly to fresh bituminous compound (item 06). The glass veil is chemically compatible with bituminous sealing compounds. Adhesive open time: 30–60 min according to the compound manufacturer’s technical data sheet.
• Horizontal damp-proof course (item 02) on the strip foundation — heat-welded bituminous membrane or PE film, extending 30 cm in both directions (wall + floor). Without it — capillary rise will dampen the insulation.
• Dimpled membrane (item 08) with dimples facing the insulation — gravity drainage towards the perimeter drain. Top edge fixed with a profile.
• Perimeter drainage (item 09) — Ø100 mm in gravel backfill, slope 0.5–1% to an inspection chamber.
• Above-ground plinth zone (item 17) — transition to termPIR® ETX or mosaic plinth render. A critical boundary between the buried and exposed insulation.

Comparison with a 3-layer foundation

Aspect	Two-layer (this one)	Three-layer
Insulation protection	dimpled membrane	protective masonry wall
System service life	50–80 years	100+ years
Price per m²	base	+30–40%
Required plinth façade protection	mosaic render	continuous clinker brick to ground level
Typical application	standard single-family homes	premium villas

Featured in the 2-layer termPIR® WS foundation system.

Documentation

termPIR® Catalogue — Residential Buildings (Gór-Stal, 2022), p. 46 — cross-section of a two-layer basement wall.

Components in this junction