How to Choose Acoustic Underlay for Floors | ANIKA

To choose the right acoustic underlay, start with the floor construction, expected loads and target impact sound rating. A mat installed beneath a floating screed has different requirements from a thin underlay fitted directly beneath a click-lock floor. This guide explains how to shortlist materials and compare test data for apartments, hotels and commercial projects.

ANIKA polyurethane (PU) acoustic underlay supplied in rolls.

What Is Acoustic Underlay and How Does It Work?

Acoustic underlay, also called acoustic underlayment, is a resilient layer installed within a floor assembly. Depending on the system, it can sit directly beneath a compatible floor finish or beneath a floating screed.

Footsteps and dropped objects cause the floor to vibrate. A resilient layer helps reduce the transfer of that vibration into the supporting structure and the resulting impact noise heard in rooms below. The result depends on the complete assembly and its installation.

Example floor build-up with acoustic underlay and a tile or stone finish.

How to Choose the Right Acoustic Underlay

1. Identify the floor layers. Record the structural subfloor, any screed and the final finish. For laminate, engineered wood or SPC, check the flooring manufacturer's limits for underlay thickness and compression. If the flooring has an attached pad, confirm whether an additional underlay is permitted.
2. Check loading and compression. For floating screeds, ask for mechanical data for the proposed grade. Review compression under the design load and long-term deformation, along with dynamic stiffness if the project specification calls for it.
3. Match the report to the project. Ask for the test standard, report date, underlay grade and tested floor build-up. Compare the slab or subfloor, screed, finish and ceiling construction with your project drawings.

How to Read IIC, ΔIIC and ΔLw

• IIC rates the impact sound insulation of the tested floor-ceiling assembly. A higher IIC indicates better impact sound insulation under that test method.
• ΔIIC expresses the improvement measured against a reference assembly under the applicable test method.
• ΔLw expresses weighted impact sound reduction in decibels under a different test method.

Compare products using the same metric and a comparable test build-up. When a specification calls for an assembly IIC rating, request the floor-ceiling test report that supports that rating.

View ANIKA AK05RF recycled rubber underlayment

Rubber vs. Foam Underlay

Rubber acoustic underlay is an option for selected concrete-based floors and floating screed assemblies. For projects with sustained loads, compare compression and acoustic test data for the proposed rubber grade.

Foam underlay includes polyurethane (PU), XPE and EVA grades with different thicknesses and compression properties. Selected grades can be used beneath compatible floor finishes. ANIKA also supplies a 16 mm PU option for compatible floating screed assemblies.

Use the available floor height, loading conditions and tested assembly to compare grades. Material density alone gives an incomplete picture of impact sound performance.

Frequently Asked Questions

Does a thicker underlay reduce more footfall noise?

Thickness affects how the underlay fits and behaves under load. Use impact sound results and compression data for the specific grade to judge whether it suits your floor system.

Can acoustic underlay be used with underfloor heating?

Confirm approval for the proposed underlay, floor finish and heating system. Ask for the underlay's thermal resistance and operating temperature limits, then check them against the floor system requirements.

What information should I send for a quotation?

Send a floor section or list of layers, the final floor finish, the target impact sound rating, the required area in square metres and the delivery destination.