Junction function
Three-layer basement wall = full 3-layer construction from foundation to roof with termPIR® AL in the cavity. Vs two-layer basement (p. 46):
- External protection is better (clinker vs only bitumen+membrane) — the basement facade visible above ground level is naturally decorative.
- Durability 80+ years for clinker vs ~25 years for a typical plinth.
- Cost 40–60% higher than two-layer construction.
- Required footprint wider by 6–8 cm around the foundation.
The basement floor is identical to the two-layer version — termPIR® AL under the screed (items 13, 14).
Critical installation aspects
- termPIR® AL in the basement cavity (item 03) — bonded full-surface with PUR to the load-bearing wall; in a three-layer basement, AL can be used (vs WS in the two-layer version) because the insulation is enclosed in the cavity between the walls — no contact with groundwater.
- Stainless steel ties (item 05) — AISI 304/316 minimum; under ground conditions galvanised ties will corrode within 3–5 years.
- Bituminous waterproofing (item 08) — on the external side of the clinker facing leaf (item 04); 2 layers of Botament / Bibrol bitumen, 2.5 mm thick.
- Dimpled foundation membrane (item 09) — continues the waterproofing while mechanically protecting the bitumen from the soil backfill.
- Perimeter drainage (item 10) — perforated DN 100 pipe at footing level (not higher); 1% fall to the inspection chamber.
- Slab ring beam (item 17) — thermal break with a termPIR® AL strip 30–50 mm; without it a linear thermal bridge between the basement (cool) and the ground floor (warm) causes condensation inside the ground floor in winter.
- Horizontal damp-proof course (item 11) — 5 mm SBS bitumen membrane at footing level; must absolutely be continued with an overlap onto the above-ground wall.
Documentation
Technical Catalogue termPIR® — Residential Buildings (Gór-Stal 2022), page 46 — Three-layer basement wall (light-type waterproofing). Scale 1:10.
Components in this junction
Insulation (3)
- 03 Wall thermal insulation — termPIR® AL board
- 13 Floor thermal insulation — termPIR® AL board
- 14 Floor thermal insulation — continuation
Fastener (1)
- 05 Wall tie (stainless steel anchor)
Sealant (1)
- 08 Bituminous waterproofing compound
Element (13)
- 01 Strip footing
- 02 Basement wall — load-bearing leaf
- 04 Basement wall — facing leaf (clinker)
- 06 Cement render (external)
- 07 Cement-lime plaster (internal)
- 09 Dimpled foundation membrane
- 10 Perimeter drainage
- 11 Horizontal damp-proof course
- 12 Lean concrete
- 15 Cement screed
- 16 Basement floor finish
- 17 Ring beam and slab over basement
- 18 Finishing layer bonded on mesh to the plinth