Top floor ceiling — wall plate junction

Junction function

Triple-junction point in a single-family house with an unused attic:

1. Top floor ceiling insulated with termPIR AL/WS (item 12) — insulation laid on the ceiling from the attic side.
2. External wall insulated with termPIR ETX (item 06) — ETICS system.
3. Wall plate (item 09) — critical point — timber embedded in the ring beam, a natural thermal bridge trap.

Insulation continuity requires additional wall plate insulation (items 10, 11) — without it, the ring beam / wall plate thermal bridge reduces the ceiling insulation effect by 15-25% (thermographic measurements).

Critical installation aspects

• Ceiling thermal insulation (item 12) — termPIR AL/WS laid without gaps over the entire ceiling surface, butting up to the knee wall. Boards cut to the slope.
• Wall plate insulation (item 11) — strip of termPIR AL/WS min. 50 mm thick wrapped around the wall plate (top + side from the attic). Without it, a thermal bridge through the timber.
• Additional wall plate insulation (item 10) — optional insulation strip between rafters above the wall plate (where the structure allows).
• Junction with ETX wall insulation (item 06) — termPIR ETX strip overlaps onto the wall plate insulation from the façade side; overlap min. 50 mm.
• Aluminium tape (item 13) on all board joints — vapour-tightness.
• PU adhesive (item 14) between individual termPIR layers — mechanical reinforcement + sealing.

Typical U-values

For termPIR AL 200 mm on the ceiling + ETX 150 mm on the wall + 50 mm wall plate insulation:

• Ceiling: U ≈ 0.12 W/(m²·K)
• Wall (ETICS): U ≈ 0.16 W/(m²·K)
• Linear thermal bridge at wall plate Ψ ≈ 0.02 W/(m·K) — with wall plate insulation
• Without insulation: Ψ ≈ 0.18 W/(m·K) → energy loss 9× greater

Present in systems: top floor ceiling termPIR AL, ETICS wall termPIR ETX.

Documentation

termPIR catalogue — Single-Family Houses, p. 64 — top floor ceiling + wall plate insulation + knee wall.

Components in this junction