How to Soundproof a Floor UK — Step by Step Guide

Floor noise is one of the most common acoustic complaints in UK homes — and one of the most solvable. Whether you're dealing with footstep noise travelling to the flat below, airborne sound from a home cinema, or impact vibration from a gym space above, understanding how to soundproof a floor correctly will determine whether your project succeeds or fails.

This guide covers the physics of floor noise, UK Building Regulations requirements, and a complete step-by-step approach to achieving meaningful sound reduction — including which products work for which scenarios.

What Causes Floor Noise? Impact vs Airborne Sound

Effective soundproofing starts with diagnosing the noise type. Floor noise comes in two distinct forms, and they require different solutions:

Impact Noise

Impact noise is generated when something physically contacts the floor structure — footsteps, chair legs, dropped objects, children running. The energy travels through the floor construction as structure-borne vibration, radiating as sound from the ceiling below. It is characterised by sharp, percussive sounds.

Solution: Resilient underlay that decouples the floor covering from the structural slab or joists. Our 6mm Recycled Rubber Acoustic Underlay achieves 74 dB ΔLw — the highest impact noise reduction in its class.

Airborne Noise

Airborne noise — voices, music, TV — travels as pressure waves through air and into the floor structure when it encounters a rigid surface. Once in the structure, it radiates as sound on the other side.

Solution: Mass and absorption. Dense materials absorb airborne energy. Our 12mm Acoustic Flooring System achieves 58 dB airborne sound reduction through a combination of density and resilience.

Flanking Noise

Often overlooked, flanking transmission occurs when sound travels around the direct path — through walls, perimeter connections, and service penetrations. A perfectly isolated floor can still fail acoustically if flanking paths are left untreated. This is why perimeter details (skirting boards, wall-floor junctions) matter as much as the underlay itself.

UK Building Regulations Part E — What Floors Must Achieve

In England and Wales, Approved Document E sets minimum acoustic performance requirements for residential separating floors:

For new-build developments, Pre-Completion Testing (PCT) is typically required by Building Control. Products must be tested to EN ISO 10140 and ISO 717-2 standards. Our 6mm Rubber Underlay and 12mm Acoustic System both carry the performance documentation needed for PCT submissions.

In Scotland, Section 5 (Noise) of the Building Standards applies; in Northern Ireland, Technical Booklet G. Requirements differ slightly from England and Wales but the underlays covered here meet all regional standards.

Step-by-Step: How to Soundproof a Floor

Phase 1: Assessment and Planning

1. Identify the noise type. Is it impact (footsteps) or airborne (voices)? Impact noise dominates in most domestic situations.
2. Check floor height restrictions. How much floor raise can you accommodate? Even 3mm makes a difference; 12mm is significant near door frames and on stairs.
3. Check Building Regs status. Is this a Part E-relevant project? New build, conversion, or renovation?
4. Assess the existing substrate. Concrete slab, suspended timber, or existing screed? This determines which underlay system to specify.

Phase 2: Substrate Preparation

1. Clear the subfloor. Remove all existing floor coverings and underlays. Any debris between the new underlay and substrate will create point loading and reduce acoustic performance.
2. Flatten the subfloor. Level high spots with a grinder; fill low spots with a self-levelling compound. Maximum tolerance: ±3mm over 1800mm.
3. Treat damp. On concrete, apply a damp-proof membrane (DPM) — 1000-gauge polythene is standard. Moisture under acoustic underlay accelerates degradation and can cause mould.
4. Check for services. Note the location of pipework and underfloor heating elements before laying. UFH pipes must be pressure-tested before covering.

Phase 3: Installing Acoustic Underlay

1. Roll out the underlay. Begin at one wall and work across the room. For rubber underlay, lay rolls perpendicular to the direction of the finished floor boards where possible.
2. Butt-join all edges. Never overlap edges. Overlaps create hard spots that reduce acoustic performance and can telegraph through soft floor coverings. Use acoustic tape on all joints.
3. Turn up at perimeter walls. Run the underlay 15mm up the wall at all perimeters. This creates an acoustic break between the floating floor and the wall structure, preventing flanking through the base of the wall.
4. Tape all joints. Use self-adhesive acoustic tape on every butt joint. This prevents air gaps which act as acoustic weak points.

Phase 4: Laying the Finished Floor

1. Install as a floating floor. The floor must not be fixed, glued, or screwed to the subfloor at any point. If the floor is attached to the structure, it bypasses the acoustic underlay entirely.
2. Leave expansion gaps. Follow the flooring manufacturer's instructions for expansion gaps at walls and thresholds. Gaps should not be filled with rigid sealant — use a flexible acoustic mastic.
3. Fit threshold strips. At doorways, use flexible threshold strips rather than rigid solid ones. Rigid thresholds clamp the floor to the substrate.
4. Fit skirting boards correctly. Skirting boards must sit above the floor — never screwed through the floor into the subfloor. The base of the skirting should clear the floor by 1–2mm to maintain acoustic independence.

Products for Each Scenario

Concrete Floor (e.g. ground floor flat, basement conversion)

Concrete is the most efficient sound transmission medium in residential construction. A high-performance rubber underlay is essential.

Recommended: 6mm Recycled Rubber Acoustic Underlay (74 dB ΔLw) — rated for use under screed and suitable for direct use on concrete. For full Part E compliance on separating floors, add the 12mm Acoustic Flooring System.

Timber Joist Floor (e.g. Victorian terrace, period conversion)

Timber joist floors have inherently poor acoustic performance due to air gaps between joists and flexible decking. They require mass added to the deck and resilient isolation.

Recommended: SilentMat 15mm Acoustic Underlay on the existing deck, or the 12mm Acoustic Flooring System with additional mass board. Consider also resilient bar systems for the ceiling below.

Screed (new build or refurb with floating screed)

Under-screed acoustic underlay must be robust enough to withstand the alkaline environment of fresh screed and the compressive loads during screeding.

Recommended: 6mm Recycled Rubber Acoustic Underlay — specifically rated and tested for under-screed use. It complies with UK Building Regs and withstands the chemical and mechanical demands of screed installation.

LVT / Laminate (renovation, no height restriction)

Recommended: 3mm Recycled Rubber Acoustic Underlay (54 dB ΔLw) or Cork & Rubber Composite. Both have low TOG ratings for UFH compatibility and a thin profile that minimises floor-level rise.

Common Mistakes That Kill Acoustic Performance

• Overlapping underlay edges. Creates ridges, hard spots, and acoustic bridges. Always butt-join.
• Forgetting to tape joints. Untaped joints allow structure-borne vibration to transfer across without attenuation.
• Screwing the floor to the subfloor. A single screw through the floor bypasses the underlay and creates a rigid bridge. If you must fix, use resilient fixings.
• Using the wrong product. Standard foam underlay is not acoustic underlay. It has negligible ΔLw values. Always specify products tested to ISO 717-2.
• Ignoring flanking paths. Fitting the best underlay in the world won't help if the skirting boards are screwed through the floor into the joists. Think about the whole system.
• Installing over wet screed. Always allow screed to cure fully (typically 28 days for traditional sand/cement screed) before installing acoustic underlay.

Frequently Asked Questions

1. Can I soundproof a floor without raising its height?

Our 3mm Recycled Rubber Underlay and 3mm Cork Rubber Composite add minimal height while still delivering 54 dB ΔLw impact noise reduction. These are the preferred options in rooms where door clearances are tight.

2. Does soundproofing a floor also reduce noise coming from below?

Impact noise travels downward (footsteps from above). Airborne noise travels in both directions. A good acoustic underlay above helps with airborne sound from below, but to reduce impact noise coming from the floor above, you need acoustic treatment on that upper floor.

3. Is acoustic underlay enough on its own for Building Regs?

For conversions, a high-performance underlay like our 6mm Rubber (74 dB) combined with a floating floor typically achieves the Part E conversion threshold (L'nT,w ≤ 62 dB). For new-build separating floors (≤ 45 dB), a full system approach using the 12mm Acoustic Flooring System is recommended.

4. What is a resilient bar and when do I need one?

A resilient bar (or sound bar) is a metal channel fixed to ceiling joists, onto which plasterboard is attached. It creates a decoupled ceiling below the floor above — essential for achieving high airborne isolation in timber joist constructions. Our resilient bar systems complement acoustic floor underlay to provide a complete floor-to-ceiling solution.

5. Can I soundproof a floor in a rented flat?

Yes. A floating floor with acoustic underlay is reversible — no permanent fixings required. The 3mm Recycled Rubber Underlay under a click-lock LVT floor can be installed and removed without damage to the substrate.

6. How long does acoustic underlay last?

High-quality recycled rubber underlay has a service life of 30+ years under normal residential conditions. It does not compress permanently under floor loads, unlike foam underlays which degrade within 5–10 years. Once installed correctly, our rubber underlays maintain their ΔLw performance for the life of the building.

Browse our full range: Acoustic Underlay Collection — including our best-selling 6mm Rubber Underlay and 12mm Acoustic Flooring System.