Terrace over living space (termPIR® AL)

Junction function

A terrace over a living space is the most demanding detail in a single-family house, second only to a balcony. Unlike a balcony (eaves, short cantilever element), a terrace is a full floor of surface requiring:

1. Waterproofing that is watertight across the entire area.
2. A 1.5% slope for rainwater drainage.
3. Thermal insulation eliminating the thermal bridge through the slab.
4. A frost-resistant surface resistant to UV radiation.

Missing any of these layers = leakage into the apartment below + condensation on the ceiling = a standard court dispute between residents of different floors.

Critical installation aspects

• Waterproofing (item 02) — the most important element; options:
  • SBS torch-on bitumen membrane 5 mm — economical standard.
  • Liquid membrane (Botament BM 92, Maris BS-9) — better for terraces with complex geometry (gutters, balustrade posts).
  • Cold-applied bituminous mat (Kerakoll Aquastop) — fastest, medium durability.
• Waterproofing overlaps — minimum 10 cm; at the kerb and under the surface, 20 cm of vertical overlap onto the wall.
• termPIR® AL (item 04) — under the waterproofing; not on top of it (water would penetrate the insulation); typically 12–20 cm thick to meet WT 2021 requirements.
• PE film (item 05) — between termPIR and the slope screed; optional, recommended: protects against cement laitance seeping into the insulation.
• Slope layer (item 06) — cement screed at 1.5% towards the drain or eaves (NOT 1% — the minimum for rainwater is 1.5% per PN-B-10250).
• Terrace drains — typically 2 drains for a terrace >10 m² (redundancy in case of clogging by leaves); DN50 diameter + leaf strainer.
• Terrace kerb — height min. 15 cm, bonded under the waterproofing (NOT on top of it!); joints sealed with epoxy silicone.
• Balustrade — anchored in the face of the slab or in the slope layer with additional sealing; NEVER in the screed under the surface — water will penetrate after the first winter.

Documentation

Technical Catalogue termPIR® — Residential Buildings (Gór-Stal 2022), page 63 — Floors and ceilings, insulation detail of a terrace over a living space. Scale 1:10.

Components in this junction