Flats, timber floors, concrete slabs and machinery
Floor Soundproofing: How to Reduce Impact and Airborne Noise
Diagnose footsteps, voices, machinery vibration and flanking paths before choosing an underlay, floating floor, joist treatment or ceiling system.
A floor can transmit footsteps, dropped objects, voices, music and machine vibration, but these sources do not require the same treatment. Impact sound should usually be reduced as close to the source as practical, while airborne noise may require changes to the complete floor–ceiling assembly. Where access to the upper floor is unavailable, a ceiling treatment from below may be the only practical building intervention, but it is not equivalent to treating the source floor. For the wider neighbour-noise decision process, see the noisy neighbours soundproofing guide.
Successful floor soundproofing depends on the existing structure, floor finish, joists or slab, ceiling below, perimeter junctions and adjoining walls. An underlay or mat cannot be assessed in isolation from the complete construction.
How can noise through a floor be reduced?
For footsteps and dropped objects, the most effective starting point is often a resilient floor finish, underlay or floating construction installed where the impacts occur. For voices and television passing between floors, the assembly may need additional mass, cavity absorption, airtightness and sometimes mechanical separation at the floor, ceiling or both. Machine vibration should be addressed at the equipment connection before treating a whole room. Any solution can be limited by rigid perimeter contact, walls, joists, ducts, stairs and other flanking paths.
At a glance
- Impact and airborne sound are different: footsteps excite the structure directly, while voices and television begin as pressure waves in the air.
- Treat impact near the source where possible: a resilient layer above the structural floor can reduce energy before it enters the building.
- A ceiling is not the same as an upper-floor treatment: receiver-side work may help but can remain limited by joists, walls and other paths. See the soundproofing ceilings guide for the receiving-room approach.
- Floating means isolated: a deck rigidly touching walls, pipes or fixings is not functioning as a fully floating construction.
- Underlay data needs context: a laboratory impact-improvement rating does not equal the final field performance between flats.
- Check practical constraints: floor height, doors, stairs, kitchens, underfloor heating, structure, moisture, fire and lease conditions all matter.
Impact, Airborne, Machinery and Flanking Noise
Several mechanisms may occur simultaneously. The correct response depends on what creates the disturbance and how the floor is connected to the rest of the building.
Impact noise
Examples: footsteps, heels, dropped objects, moving chairs and children playing.
Route: the impact excites the floor finish, deck, joists or slab directly and re-radiates into rooms below.
Priority: reduce the impact at source where access and ownership allow.
Airborne noise
Examples: voices, television and music.
Route: sound passes through the floor–ceiling construction, gaps, service penetrations and connected cavities.
Priority: assess both leaves of the assembly, cavity and perimeter airtightness.
Machinery vibration
Examples: washing machines, pumps, treadmills, exercise equipment and speakers.
Route: rigid feet, frames or mounts inject vibration into the slab or joists.
Priority: correct imbalance and isolate the source before adding a general floor layer.
Flanking transmission
Examples: noise remains after underlay or a ceiling has been installed.
Route: walls, joists, stairs, façades, ducts and rigid perimeter contact carry sound around the treated area.
Priority: inspect the complete junction network rather than repeatedly adding layers.
Should the Floor or the Ceiling Be Treated?
Access to the source floor
Where footsteps originate in the floor above and access is available, a compatible resilient floor finish, underlay or floating system can reduce impact energy before it enters the structure. This is often the more direct approach for impact noise.
No access to the floor above
A resiliently supported or independent ceiling below may improve impact and airborne sound insulation, but it does not remove the impact at source. Joists, walls and perimeter junctions can continue to transmit vibration.
Noise travelling down to a neighbour
If your own floor is the source, treating it can protect the room below. The final finish, resilient layer, deck stiffness, perimeter isolation and structural floor must be considered together.
Airborne noise between floors
Voices and music may require cavity absorption, additional mass and airtightness in the floor–ceiling assembly. A soft floor finish that helps footsteps may have limited effect on airborne sound.
Where to Start: Quick Diagnostic Overview
| What you notice | First route to investigate | Useful next step |
|---|---|---|
| Hard heels are much louder than soft footwear | Impact transmission from the upper floor finish | Check whether carpet, resilient underlay or a tested hard-floor system can be installed at source. |
| Voices and television are audible as well as footsteps | Combined airborne and impact transmission through the complete assembly | Inspect floor gaps, joist voids, ceiling condition, penetrations and flanking walls. |
| A washing machine or treadmill shakes the floor | Mechanical coupling, imbalance or unsuitable support | Service and level the machine, identify operating loads and assess an appropriate source-isolation arrangement. |
| Noise is strongest at skirtings or party-wall junctions | Rigid perimeter contact or flanking through adjoining walls | Inspect the floor edge, skirting fixings, joist direction and wall junction before adding another central floor layer. |
| A concrete floor carries low-frequency thuds over a wide area | Impact or machine vibration spreading through a continuous slab | Identify the source position and compare source-side isolation with room-side treatments. |
| Noise remains after a ceiling has been upgraded | Flanking through joists, walls, services or incomplete ceiling isolation | Review the complete ceiling system and surrounding junctions rather than assuming the floor above is unchanged acoustically. |
How the Floor Construction Changes the Response
Suspended timber floors
Floorboards or sheet decks sit on joists above a void and ceiling. The assembly can carry impact along the joists, while gaps and penetrations allow airborne leakage. Cavity absorption may help, but it must be combined with suitable leaves, airtightness and junction control.
Concrete slabs and screeds
Concrete provides substantial mass but can distribute impact and machine vibration over a wide area. A resilient finish or floating screed can help where it is correctly designed and isolated at the perimeter.
Lightweight engineered floors
Joists, cassettes and proprietary deck systems vary significantly. Use assembly-specific evidence rather than assuming that data from a heavyweight concrete floor applies to a lightweight floor.
Ground-bearing floors
A floor on the ground may not transmit noise to a room below, but machinery vibration can still enter walls and foundations. Moisture, thermal insulation and structure may govern what can be added above it.
A Practical Diagnosis Sequence
- Describe the disturbance: separate footsteps, dropped objects, voices, music, plumbing and machine vibration.
- Identify the source and receiver: establish which room and floor create the noise and where it is most intrusive.
- Establish access: confirm whether work is possible at the source floor, receiving ceiling or both.
- Identify the construction: determine whether the floor is timber, concrete or another system and how it connects to walls and stairs.
- Inspect finishes and openings: check carpet or hard flooring, thresholds, service penetrations, floorboard gaps and skirting junctions.
- Check for machine faults: level, service and balance appliances before specifying isolation products.
- Review practical constraints: consider floor height, door clearances, stair risers, kitchens, bathrooms, underfloor heating, fire, moisture and structure.
- Decide whether testing is justified: formal impact or airborne testing may be useful where compliance, a dispute or major expenditure depends on the result.
Floor Soundproofing Interventions in Context
| Intervention | When it may help | Main limitation |
|---|---|---|
| Carpet and resilient underlay | Reduces light impact from walking and objects at the source. | Usually provides limited improvement to voices, music and low-frequency structural vibration. |
| Resilient layer below a hard finish | A hard floor is required and the complete tested build-up is compatible with the base and finish. | Thin product data alone does not establish the field result; rigid grout, fixings and edges can bridge the layer. |
| Floating overlay deck | More substantial source-side impact isolation is required and floor height and loading permit it. | Doors, stairs, kitchens, services and perimeter details can make the build-up impractical or create bridges. |
| Joist-void absorber and added floor mass | A suspended timber floor is open and airborne transmission through the assembly is important. | Absorber alone is not soundproofing, and added mass must be checked structurally and coordinated with the ceiling below. |
| Resilient or independent ceiling below | There is no access to the upper floor or combined airborne and impact improvement is required. | It reduces ceiling height and can remain limited by joists, walls, services and untreated source-floor impacts. |
| Machine isolation pads or plinth | A known machine injects vibration through its feet or frame. | The isolator must suit the machine weight, operating speed and stability; a generic soft pad can worsen movement or fail. |
Floating Floors and Resilient Underlays
A floating floor is separated from the supporting structure by a resilient layer and remains isolated from surrounding walls and penetrations. The term should not be used for any loose-laid floor covering.
Performance depends on the complete build-up: structural base, resilient layer, load-distribution deck or screed, final finish, perimeter strip, services and workmanship. The resilient layer must support the permanent and imposed loads without being too stiff, excessively compressed or unstable. Product thickness or material name alone is not a specification.
Why perimeter isolation matters
A floating deck that touches masonry, pipes, thresholds or rigid skirting fixings creates a mechanical bridge. Even a well-selected resilient layer can be undermined by hard contact around the room edge.
Suspended Timber Floors
Timber floors are multi-leaf constructions: upper deck, joists and cavity, and the ceiling below. Airborne and impact performance depends on all of them.
Upper deck and finish
A resilient finish or floating overlay can reduce impact at source. Added deck mass may help airborne insulation but must be compatible with joist capacity and deflection.
Joist cavity
A suitable porous absorber can reduce cavity resonance. It does not replace the mass and separation of the floor and ceiling leaves.
Ceiling below
The ceiling mass, supports, penetrations and perimeter determine how much sound is re-radiated into the lower room. Resilient support can reduce coupling if rigid bridges are avoided.
Joist and wall junctions
Joists embedded in masonry and continuous floorboards can carry vibration into side walls. A central floor treatment does not automatically control these routes.
Concrete Floors and Screeds
Concrete floors normally provide useful airborne mass, but hard finishes can transmit impact efficiently. A resilient floor covering, floating screed or overlay may reduce impact where the complete assembly is designed for the slab and imposed loads.
Do not assume that an impact-improvement figure measured on one concrete reference floor will be reproduced on a timber or lightweight floor. Underfloor heating, screed thickness, drying, moisture, tile adhesives and movement joints also affect the design.
Machinery, Treadmills and Gym Equipment
Machine vibration should be addressed as a source-isolation problem before treating the whole floor. Washing machines should be level, stable and mechanically sound. Treadmills, free weights and exercise equipment create different dynamic loads and may require different approaches.
A soft pad is not automatically a safe isolator
An isolator must suit the supported mass, centre of gravity, forcing frequency and required stability. Material that is too soft, too stiff or unevenly loaded can transmit vibration, allow excessive movement or create a safety risk.
Perimeters and Flanking Transmission
Floor treatments are frequently limited by rigid contact at room edges or sound travelling through connected construction. Common routes include:
- floating decks touching walls, door thresholds or pipes;
- skirtings fixed through the resilient edge into the deck;
- continuous joists or slabs extending into adjoining rooms;
- stairs, walls, façades and service risers connected to the floor;
- gaps around ducts, drainage, heating and electrical penetrations.
Sealing and isolation details must remain compatible with fire stopping, movement, moisture and access requirements. Connected walls may need separate investigation; see the wall soundproofing guide.
Do Carpets, Rugs and Acoustic Underlays Work?
Carpets and suitable underlays can reduce light impact noise at source and are often a proportionate first measure for footsteps. Rugs can help locally but leave untreated routes around them.
They should not be presented as a general solution for voices, bass or machine vibration. An underlay marketed as “acoustic” should be assessed using relevant test data for the complete floor build-up and intended final finish.
Performance Ratings and Field Testing
L′nT,w: field impact performance
This weighted standardised impact sound pressure level is determined between rooms. Lower numerical values indicate better impact sound insulation.
DnT,w + Ctr: field airborne performance
This describes airborne sound insulation between rooms and includes the installed separating construction and flanking transmission.
ΔLw: floor-covering improvement
A laboratory weighted reduction in impact sound pressure level can help compare floor coverings or floating systems under defined test conditions. It is not the same as the final L′nT,w between occupied flats. The building acoustics glossary explains the principal rating terms.
Tapping-machine limitations
Standard impact testing is useful for comparison and compliance, but it does not reproduce every real source such as children jumping, dropped weights or low-frequency exercise equipment.
Floor Soundproofing Diagnostic Matrix
| Observation | Possible path | Useful diagnostic check | Possible response | Important limitation |
|---|---|---|---|---|
| Footsteps and heel clicks from the flat above are dominant | Impact transmission from the upper finish into the structural floor and ceiling below | Compare hard footwear, soft footwear and different source positions if cooperation is possible | Source-side carpet, tested resilient underlay or a compatible floating system; otherwise assess a ceiling below | Receiver-side ceiling work is not equivalent to removing the impact at source |
| Voices and television pass between floors | Airborne transmission through the floor–ceiling assembly, gaps and flanking paths | Inspect floorboard gaps, service penetrations, ceiling openings and adjoining walls | Consider cavity absorption, airtightness, added mass and mechanical separation as a complete assembly | A soft underlay selected for impact noise may provide little airborne improvement |
| A washing machine or treadmill causes vibration | Direct mechanical coupling, imbalance or resonance of the floor and machine | Check levelling, machine condition, speed dependence and vibration at nearby walls | Repair the source and design an appropriate stable isolation arrangement | Generic pads are not selected from colour, thickness or softness alone |
| Noise remains around the room edge after underlay is installed | Rigid perimeter bridge or flanking through walls, skirtings and thresholds | Inspect edge strips, fixings, doorways, pipes and junctions | Correct confirmed bridges and assess the connected walls and structure | Adding another central layer will not repair rigid edge contact |
| Low-frequency thuds are widespread across a concrete slab | Impact or machinery vibration spreading through the continuous structure | Compare source locations and determine whether the disturbance follows one machine or activity | Prioritise source control and assess a floating treatment only after confirming the load and route | A room finish cannot always isolate a continuous slab or connected structural frame |
These checks provide diagnostic indications rather than proof. Formal airborne or impact testing may be appropriate before substantial work or where a regulatory or lease dispute depends on the result.
Building Regulations, Leases and Permissions
Approved Document E in England
Approved Document E covers resistance to sound in defined Building Regulations situations in England. It is not a universal retrofit standard or comfort guarantee for every existing flat.
- Relevant purpose-built dwelling separating floors use a minimum airborne value of DnT,w + Ctr 45 dB and a maximum impact value of L′nT,w 62 dB.
- Relevant dwellings formed by material change of use use 43 dB airborne and 64 dB impact values.
- Lower L′nT,w values indicate better impact sound insulation.
- Wales, Scotland and Northern Ireland publish separate requirements and guidance.
Existing flats and floor-finish changes
Replacing carpet with timber, laminate, tile or another hard finish can increase impact noise in the flat below. Check the lease, freeholder or managing-agent requirements before changing the floor finish or carrying out structural work.
Other considerations may include structural loading and deflection, fire resistance and penetrations, moisture and ventilation of suspended floor voids, thresholds and stairs, underfloor heating, electrical services and listed-building controls.
Where work forms part of a new dwelling, conversion or other controlled building work, confirm the applicable Building Regulations and testing requirements with the relevant building-control body.
Floor soundproofing is not only an acoustic detail
Additional mass, raised floor levels and new resilient layers can affect structure, doors, stairs, kitchens, bathrooms, fire stopping, damp control and accessibility. The complete design should be coordinated before materials are ordered.
When Specialist Advice Is Useful
- The floor construction or principal transmission route is unknown.
- Low-frequency thuds, vibration or several flanking paths are present.
- A formal Building Regulations, planning, lease or dispute-related target applies.
- A floating floor, heavy overlay, new screed or structural alteration is proposed.
- Machinery or gym equipment requires a stable vibration-isolation design.
- Before-and-after airborne or impact testing is needed to quantify performance.
Frequently Asked Questions
What is the best way to soundproof a floor?
There is no universal best system. First identify whether the main problem is impact noise, airborne noise, machinery vibration or flanking. The appropriate treatment depends on access, timber or concrete construction, final floor finish, ceiling below and practical constraints.
How do I soundproof a floor from noisy neighbours upstairs?
If the noise is impact from the floor above, treating the source floor is usually the most direct approach, but it requires access and cooperation. Where that is not possible, a resiliently supported or independent ceiling below may help, subject to flanking and space limitations.
Does acoustic underlay stop voices and television?
Most underlays are primarily intended to reduce impact from walking. Airborne noise through a floor may require changes to the complete floor–ceiling assembly, including mass, cavity absorption, airtightness and mechanical separation.
Is a floating floor better than carpet?
A properly designed floating floor can provide more substantial impact isolation than carpet, but it is deeper, heavier and more dependent on perimeter and junction details. Carpet may still be a proportionate first measure for ordinary footsteps.
Can mineral wool between joists soundproof a floor?
Mineral wool can reduce cavity resonance, but it does not soundproof the floor by itself. Performance depends on the upper deck, ceiling leaf, supports, airtightness and flanking junctions.
Can I install hard flooring in a flat?
Check the lease, freeholder or managing-agent requirements first. Hard flooring can increase impact noise below, and the permitted floor finish or required acoustic layer may be specified by the building’s documents.
Will rubber mats stop treadmill or washing-machine vibration?
They may help where selected for the supported load and operating conditions, but a generic mat is not a guaranteed solution. Check machine condition, levelling, stability and forcing frequency before selecting an isolator.
How much improvement will floor soundproofing provide?
A reliable figure cannot be given from the product list alone. The result depends on the existing assembly, complete treatment, installation, source spectrum and flanking transmission. Use relevant test evidence and field testing where a numerical outcome matters.
Standards and Official References
- Approved Document E: resistance to the passage of sound in England.
- BS EN ISO 10140-3: laboratory measurement of impact sound insulation.
- BS EN ISO 16283-1: field measurement of airborne sound insulation between rooms.
- BS EN ISO 16283-2:2020: field measurement of impact sound insulation.
- BS EN ISO 717-1: rating of airborne sound insulation.
- BS EN ISO 717-2:2020: rating of impact sound insulation and floor-covering improvement.
Technically reviewed by Sebastian Paszek
Environmental Noise Measurement and Building Acoustics Specialist
Sebastian Paszek holds the Institute of Acoustics Certificate of Competence in Environmental Noise Measurement, awarded in 2018. His technical experience includes site noise diagnostic surveys, environmental noise measurement, floor impact sound insulation testing, investigation of noise transmission in domestic properties, structural acoustic analysis for domestic properties, and acoustic assessment of windows, glazing and building openings.
Publisher note: This technical guide is published by The Soundproof Ltd under the editorial direction of Sebastian Paszek. The Soundproof Ltd also operates The Soundproof Windows, a separate commercial acoustic window business. This website provides educational technical information and does not offer project-specific recommendations through this guide.