Voices, music and traffic
Sound travels through the air and can pass through building elements, openings and gaps. The response may involve walls, ceilings, doors, windows and junctions together.
Understand the noise before choosing insulation
Acoustic Insulation:Understanding Sound Control
A quieter space starts with identifying how sound travels. Learn the difference between sound absorption and sound insulation, where glass mineral wool can help, and how our Knauf ceiling rolls fit into a complete building solution.
Three different acoustic problems
What type of noise are you hearing?
Acoustic insulation is often discussed as though every noise problem has the same solution. Voices from another room, footsteps above you and echo inside a room behave differently. Start with the source and the route the sound takes.
Footsteps and moving furniture
Vibration enters the structure and travels through connected elements. Resilient layers, isolation and careful construction details may be needed; adding ceiling rolls alone is not a complete solution.
Echo inside the room
Sound reflects from surfaces and builds up within the space. Suitable absorptive finishes can reduce reverberation, but this differs from stopping noise travelling between rooms.
Two terms worth separating
Sound absorption versus sound insulation
Both matter to acoustic comfort, but they describe different effects. A sound-absorbing material does not, by itself, make a room soundproof.
Sound absorption
Porous materials such as mineral wool absorb some sound energy rather than reflecting all of it. In a suitable cavity, this can contribute to the acoustic behaviour of the assembly.
Absorptive room finishes can also help control echo. Insulation hidden above a closed ceiling should not be treated as equivalent to an exposed, tested acoustic ceiling or panel system.
Sound insulation
Sound insulation describes how a building element limits sound transmission from one space to another. Linings, mass, separation, cavity treatment and airtightness work together.
Doors, windows, service openings and gaps can limit the result. A complete system needs to be selected and detailed for the sound problem being addressed.
Read Knauf’s acoustic performance guidance ↗ and the YourHome noise-control guide ↗ for the underlying principles. Overseas regulatory examples are not South African project specifications.
Look beyond a single material
Where glass mineral wool can help
Glass mineral wool provides sound absorption and can contribute within a suitable building assembly. The performance achieved depends on the exact product, fitting, linings, framing and connections.
For ceiling projects, consider the complete ceiling and roof-space arrangement. Sound can bypass a separating wall through a shared void or follow other routes through the building. Filling one cavity does not address every path.
Our glass wool insulation guide explains the material. For the ceiling application and our product range, visit ceiling insulation.
Set a measurable specification
What acoustic ratings can tell you
Sound reduction is assessed for an assembly, such as a wall or floor-ceiling construction. Look for test information that matches the proposed build-up, rather than a claim for an insulation roll alone.
Rw and STC are measures used for airborne sound insulation. NRC and sound absorption coefficients describe absorption. They answer different questions and should not be used interchangeably.
R-value is a thermal measure
A thermal R-value indicates resistance to heat flow. It does not establish a decibel reduction or a sound-insulation rating for your ceiling.
We do not assign a standalone soundproofing percentage or dB reduction to our four ceiling rolls. If a project has a specified acoustic target, confirm a suitable tested construction and the exact insulation product before ordering.
Dedicated Knauf Acoustic Roll and Acoustic Batt products are separate from the four Ceiling Roll thicknesses sold on this website.
The products we actually supply
Our four Knauf Earthwool ceiling rolls
We sell 50mm, 75mm, 100mm and 135mm Knauf Ceiling Rolls. These are glass mineral wool ceiling insulation products. The figures below describe thermal performance and coverage; they are not acoustic ratings.
50mm
Knauf Earthwool Ceiling Roll
- Thermal R-value
- R1.25
- Coverage per roll
- 22.80 m²
75mm
Knauf Earthwool Ceiling Roll
- Thermal R-value
- R1.88
- Coverage per roll
- 15.36 m²
100mm
Knauf Earthwool Ceiling Roll
- Thermal R-value
- R2.50
- Coverage per roll
- 12.12 m²
135mm
Knauf Earthwool Ceiling Roll
- Thermal R-value
- R3.38
- Coverage per roll
- 9.00 m²
Do not rank these rolls for soundproofing using thermal R-value or thickness alone. Confirm suitability against the intended ceiling construction and any acoustic specification.
Plan your enquiry
Tell us about the ceiling and the noise
Describe the problem before choosing a thickness. We handle ceiling insulation installation enquiries in Johannesburg and Pretoria. Specialist acoustic design or soundproofing work may require a separate assessment.
What do you hear?
Explain whether it is speech, television, traffic, footsteps, vibration or echo. Tell us where it seems to come from and which rooms are affected.
What is already there?
Share the ceiling type, approximate area, roof-space access and existing insulation. Photos you already have can help explain the layout.
What needs to change?
Tell us whether you need a ceiling insulation quote or have a specified acoustic system. Supply the relevant construction details and product specification if available.
Common sound insulation questions
Acoustic insulation FAQs
Will ceiling insulation make my room soundproof?
No insulation roll alone can guarantee a soundproof room. Results depend on the ceiling construction and other sound paths, including walls, openings and junctions. Assess the noise source and the complete assembly before specifying work.
Is acoustic insulation the same as thermal insulation?
Some materials can contribute to both thermal and acoustic performance, but the ratings and intended applications differ. Thermal R-values do not establish sound reduction. Use the exact product and system data for the performance required.
Do you sell Knauf acoustic batts or Acoustic Roll?
This website sells four Knauf Ceiling Roll thicknesses: 50mm, 75mm, 100mm and 135mm. Dedicated acoustic batts, Acoustic Roll, acoustic panels and soundproofing foam are not part of our current range.
Which thickness is best for sound insulation?
There is no universal answer based on thickness alone. The product, cavity, linings and complete construction affect the result. For a specified acoustic target, use a suitable tested assembly rather than assuming the thickest ceiling roll is the correct choice.
Will insulation stop footsteps from upstairs?
Footsteps can transmit vibration through the structure. Cavity insulation may be one part of a designed floor-ceiling system, but resilient layers, separation and junction details may also be required. A ceiling-roll installation alone should not be promised as a solution.
Can insulation above a ceiling remove room echo?
Echo and reverberation depend on the surfaces exposed to the room. Material behind a closed ceiling is not equivalent to an exposed acoustic absorber. Consider suitable room finishes or a designed acoustic ceiling system for reverberation control.
How do I get a quotation?
Send your location, ceiling area, access details and existing insulation information through our contact page. If noise is the main concern, describe the source and the construction so the enquiry can be considered before a product is selected.
Ready to take the next step?
Planning Ceiling Insulation?Tell Us About Your Project.
Ask about our 50mm, 75mm, 100mm and 135mm Knauf Earthwool ceiling rolls. Share your ceiling area, location and existing construction. If noise is your priority, describe what you hear and where it comes from so the application can be considered before you order.
- Four ceiling roll thicknesses
- Supply-only quotations
- Installation enquiries