Knee wall — under-rafter roof W2 (termPIR® AL GK)

Junction function

Knee wall in the W2 variant — analogous to W1, but with the termPIR® AL GK composite board (item 07) as the under-rafter layer. The AL GK board runs down onto the knee wall and meets the additional plasterboard (item 11) fitted to the knee wall from the inside.

Key structural points:

1. Wall plate (item 14) seated on the knee wall masonry.
2. Between-rafter board (item 06) runs down onto the wall plate.
3. AL GK board (item 07) runs down underneath the wall plate.
4. The gap between items 06 and 07 around the wall plate is filled with low-expansion PIR foam (item 12).
5. ETX (item 13) continues the façade insulation on the outside.

Critical installation aspects

• Low-expansion PIR foam (item 12) — fills a 5–15 mm gap around the wall plate; high-expansion foam will distort the geometry = gap for air and vapour.
• termPIR® AL GK board (item 07) cut at an angle at the wall plate interface — seal with assembly foam, plasterboard tape on the joint with the additional plasterboard on the knee wall.
• Additional plasterboard (item 11) on the knee wall — continues the finish texture from the AL GK on the roof; joint taped and filled.
• ETX (item 13) continued on the knee wall all the way to the wall plate — mechanically anchored + full-surface bonded.
• PE vapour barrier (item 10) — for wet rooms below the slopes, laid before the plasterboard sub-structure.
• Knee wall ring beam (if reinforced concrete) — additionally insulate with a 30 mm termPIR® AL strip; without it a linear thermal bridge occurs at the ring beam.

This junction appears in the pitched roof — termPIR® under-rafter system.

Documentation

Technical Catalogue termPIR® — Residential Buildings (Gór-Stal 2022), page 26 — Pitched roof W II, detail of the knee wall to roof connection. Scale 1:10.

Components in this junction