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Sound insulation calculator (Rw, RA,1, R'A,1)

Select partition category

Floor separating two residential units on different floors

Partition layers

Select a structural material and optionally add a system acoustic wall lining.

Structural material

System wall lining (optional)

Partition cross-section

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Calculation results

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Sound insulation - article

Rw, RA,1 and R'A,1 sound insulation calculator

The calculator provides a preliminary assessment of partition sound insulation under PN-B-02151-3:2015-10. It converts laboratory Rw through RA,1 and the design value RA,1,R; for partitions between dwellings it applies an indicative flanking-transmission scenario Ka to compare R'A,1 with the requirement. It supports masonry and concrete with system linings, complete lightweight systems, massive double walls and composite partitions (wall + door).

How to use the calculator in 3 steps

Choose the partition category. The calculator loads the standard requirement and identifies whether RA,1,R or approximate R'A,1 is assessed.

Choose masonry or concrete with an optional system lining, or a complete tested lightweight system. For a composite partition, enter the areas and parameters of the wall and door.

For a partition between dwellings, choose the Ka scenario, then read the chain Rw → RA,1 → RA,1,R → R'A,1, the indicative verdict and the required Rw.

Calculation method — mass law and design assessment

For a homogeneous massive partition, Rw can be estimated from its surface mass:

Rw ≈ 37.5 · log₁₀(m′) − 42

where Rw [dB] is the laboratory index and m′ [kg/m²] is surface mass. The formula may only be used for homogeneous massive partitions with m′ > 150 kg/m² and does not replace test data.

Design assessment from Rw to R'A,1

The calculator does not compare catalogue Rw directly with the requirement. For laboratory data, it includes spectrum adaptation C, a one-time design margin and—where R'A,1 is required—a Ka flanking-transmission scenario:

Rw → RA,1 = Rw + C → RA,1,R = RA,1 − 2 → R'A,1 ≈ RA,1,R − Ka

C comes from the acoustic declaration, while Ka depends on adjacent partitions and junctions. Therefore, R'A,1 is an indicative design assessment, not a replacement for an acoustic design.

Composite partitions

The insulation of a composite partition with elements of different Rw (e.g. wall + door) is calculated from the weighted average of acoustic transmission coefficients τ: Rw = −10·log₁₀((S₁·τ₁ + S₂·τ₂) / S_total), where τᵢ = 10^(−Rw,i/10). The element with lower Rw dominates the final result — this is why a door with low insulation significantly reduces the Rw of the entire partition.

Requirements of PN-B-02151-3:2015

The standard specifies minimum sound insulation index values for partitions in multi-family residential buildings (Table 3):

Floor between apartments: R'A1 ≥ 51 dB
Wall between apartments: R'A1 ≥ 50 dB
Apartment-corridor/staircase wall: R'A1 ≥ 50 dB (without door), R'A1 ≥ 30–38 dB (with door, depending on anteroom)
Entrance door: RA,1,R ≥ 30 dB (with anteroom) or RA,1,R ≥ 35 dB (without anteroom)
Floor/wall to garage or technical room: R'A1 ≥ 58 dB
Floor/wall to music venue: R'A1 ≥ 65 dB
Floor residential-office (mixed-use building): R'A1 ≥ 55 dB
Wall between semi-detached/terraced houses: R'A1 ≥ 52 dB

R'A1 — apparent weighted sound reduction index, accounts for flanking transmission. RA,1,R — design index used for elements such as doors and partition walls. Values apply to multi-family residential buildings — single-family houses in semi-detached configuration have their own requirements (R'A1 ≥ 52 dB).

Sound insulation of typical building materials

Rw depends on construction, mass, stiffness and connection quality. Indicative values and selection principles:

Heavy homogeneous masonry and concrete usually achieve higher Rw. Before comparison with a requirement, the calculator converts their Rw using typical C and the design assumptions.
Reinforced-concrete floors are assessed here for airborne sound only. Compliance also requires a separate L'n,w impact-sound check.
Select lightweight walls as complete tested systems with declared Rw(C). Do not derive a result by adding values for an individual gypsum board and mineral wool.
A lining is a system of boards, frame and mineral wool. Its ΔRw depends on the base wall, and mechanical ties can reduce its effect. EPS bonded to a wall can worsen insulation through resonance, so it is not an acoustic solution in the calculator.

Approximate values based on PN-B-02151-3:2015 and manufacturer data. Actual insulation depends on workmanship quality, joint tightness, and flanking transmission paths.