Partition wall — floor mounting

Function of the junction

Bottom edge of the partition wall — UW profile (item 01) fixed to the screed (item 08) before the floor finish (item 10) is laid.

Critical element: perimeter expansion joint (item 09) — a strip of acoustic insulation (typically 10 mm XPS or polyethylene foam) around the entire perimeter of the floor, including beneath the partition wall.

Function of the expansion joint:

• Elimination of acoustic bridges — without the expansion joint, the cement screed transmits vibrations (footsteps, appliances) to all adjacent walls, multiplying sound transmission.
• With the expansion joint: the screed becomes an acoustic island, and the wall receives only the direct acoustic load from its own surface.

This is a mandatory detail for residential and office buildings — in single-family houses it is often omitted → acoustic complaints.

Critical installation aspects

• Cement screed (item 08) installed before the partition wall is erected. The perimeter expansion joint (item 09) is laid before pouring — a 10 mm strip around the entire room, plus wherever partition walls will be located.
• UW profile (item 01) on the screed, on the expansion joint — directly, without concrete underneath.
• Sealing tape (item 06) between the UW and the screed — fills micro-unevenness, prevents impulse sounds.
• Expansion plugs (item 07) every 800–1000 mm — pass through the expansion joint and into the screed. Diameter Ø6–8 mm.
• Floor finish (item 10) — tile, panel, parquet — does NOT touch the wall. Leave a 5–10 mm gap, concealed by a skirting board (plinth).
• termPIR AL/WS thermal insulation (item 03) within the CW frame (item 02) — the termPIR strip reaches the UW profile, without gaps. termPIR 40–60 mm = acoustic class A.

No expansion joint = complaint

The most common acoustic complaint in multi-family housing:

“I can hear my neighbour’s footsteps from upstairs through the partition wall, even though the wall is 100 mm + plasterboard.”

Diagnosis: lack of perimeter expansion joint. The screed transmits vibrations directly into the wall frame → flanking transmission bypasses the wall’s acoustic insulation.

Retrofit repair: impossible without breaking up the floor. Price of the expansion joint at the screed stage: ~2 PLN/lm.

Used in systems: intermediate floor termPIR AL, ground floor termPIR AL.

Documentation

termPIR catalogue — Single-Family Houses, p. 59 — partition walls, floor mounting.

Components in this junction