Trapezoidal sheet sound insulation: Recognising limits & finding better solutions

Trapezoidal sheet metal is an economical solution for roofs and walls - but sound insulation is not one of its strengths. The thin sheet steel offers practically no sound insulation. Rain pours loudly onto the surface, outside noise penetrates unhindered and the background noise becomes a problem in production halls.

Anyone who values noise protection - whether for employee comfort, to comply with noise protection requirements or for quiet workshop use - quickly comes up against the physical limits of trapezoidal sheet metal. This article shows why sound insulation does not work with trapezoidal sheet metal and which alternatives deliver better results.

Why trapezoidal sheet metal does not provide sound insulation

Sound insulation requires mass and absorbent materials. Trapezoidal sheeting offers neither:

Too thin, too light: trapezoidal sheet metal is typically only 0.5-0.75 mm thick. This low material thickness has hardly any mass. Sound waves are not blocked, but pass through almost unhindered or are transmitted as structure-borne sound.

Metal conducts sound: Sheet steel is an excellent sound conductor. Noises that hit the sheet metal are transmitted as vibrations and emitted again on the other side. The sheet acts like a membrane - similar to a loudspeaker chassis.

No absorption: Sound insulation works by absorption in porous materials. Trapezoidal sheet metal is solid and solid over its entire surface - it cannot absorb sound energy and convert it into heat.

Physical principles: Effective sound insulation requires either heavy, solid materials (concrete, masonry) or multi-layer constructions with absorbent intermediate layers. Trapezoidal sheeting does not fulfil any of these requirements.

The result: trapezoidal sheet metal offers practically no sound insulation. What is loud outside can be heard almost as loud inside - and vice versa.

Typical noise problems with trapezoidal sheet metal

Rain noise and hail

The most well-known problem: rain on trapezoidal sheet metal is extremely loud.

Raindrops: Every drop that hits the sheet metal makes an audible noise. In heavy rain, there is a continuous pattering that drowns out conversations.

Hail: Hailstones on trapezoidal sheet metal produce a deafening noise. Normal work becomes impossible in living spaces, offices or workshops.

Affected: Garages under trapezoidal sheet metal roofs, carports, workshops, storage rooms with staff, residential containers

This does not matter for warehouses without staff. However, as soon as people are permanently in the building, rain noise becomes a burden.

Outside noise penetrates unhindered

Trapezoidal sheeting does not insulate against external noise:

Road traffic: cars, lorries, motorbikes - all traffic noise is clearly audible inside the building.

Neighbourhood noise: Conversations, music, gardening work by neighbours penetrate unattenuated.

Commercial noise: machines, vehicles, construction work in the neighbourhood are a disturbing presence.

The same applies vice versa: noises from the building can be heard outside. This is problematic for businesses in residential areas with noise protection requirements. Conversations, machines and production noises must be insulated from the outside - trapezoidal sheet metal does not contribute to this.

Noise pollution in production halls

In industrial halls, a lack of sound insulation becomes a health problem:

Machine noise is reflected: The noise from production machines reflects off the trapezoidal sheet metal walls and ceilings. Instead of being absorbed, it bounces back into the hall. The background noise adds up.

Long reverberation times: Without absorbent surfaces, every sound reverberates for a long time. Intelligibility suffers, communication becomes difficult.

Health risks: Continuous noise levels above 85 dB(A) damage hearing. Such levels are quickly reached in reverberant trapezoidal sheet metal halls. Employers have to provide hearing protection - an unsatisfactory solution.

For modern hall construction projects where staff are present, trapezoidal sheet metal is problematic without additional sound insulation measures.

Improve sound insulation for trapezoidal sheet metal retrospectively

Acoustic insulation from the inside

Subsequent sound insulation measures are possible, but costly:

Acoustic panels: Acoustic panels made of mineral wool, foam or special acoustic fleece can be attached to the underside of trapezoidal sheet metal roofs. These panels absorb sound and reduce reverberation.

Insulation between purlins: For roofs with purlins, insulation can be inserted between the beams. This improves both thermal and sound insulation.

Suspended ceilings: An additional ceiling under the trapezoidal sheet creates a cavity with insulation. Significantly better sound insulation, but room height is lost.

Wall insulation from the inside: An inner shell with insulation and panelling can be fitted to trapezoidal sheet metal walls.

These measures cost time and money. The construction time is extended, the interior space is reduced and the results fall short of factory-insulated solutions.

Limits of retrofitting measures

Even with retrospective measures, limitations remain:

Rain noise remains audible: even with acoustic panels, rain on trapezoidal sheet metal remains significantly louder than with solid roofs or sandwich panels. The panels dampen, but the sheet metal itself remains the primary source of sound.

Complex and expensive: installing acoustic panels or suspended ceilings requires scaffolding, materials and specialised tradesmen. The costs often exceed the difference to factory-insulated solutions.

Loss of space: Suspended ceilings and wall insulation significantly reduce the usable area and clear height.

Never optimal: Retrofit solutions do not achieve the sound insulation values that integrated systems offer from the outset.

Subsequent sound insulation is a compromise - better than nothing, but never as good as correctly planned from the outset.

Sandwich panels: Integrated sound insulation through an insulating core

Sandwich panels for roofs and sandwich panels for walls offer significantly better sound insulation from the outset than trapezoidal sheet metal - without any subsequent measures.

How sandwich panels absorb sound

The multi-layer structure of sandwich panels is ideal for sound insulation:

Insulation core absorbs sound: The polyurethane (PU) or PIR core is a porous material that absorbs sound energy and converts it into heat. Unlike solid metal, the insulating core does not reflect sound, but absorbs it.

Multi-layer structure: The combination of outer shell, insulating core and inner shell creates a multi-layer construction. Sound waves have to pass through several material transitions - energy is absorbed at each transition.

Mass and damping: Sandwich panels have more mass than thin trapezoidal sheet metal (40-200 mm total thickness instead of 0.75 mm). Higher mass means better sound insulation.

Reduced structure-borne sound transmission: The elastic insulating core partially decouples the outer and inner shells. Structure-borne sound is not transmitted directly.

Result: Rain noise is noticeably dampened, external noise is significantly reduced and machine noise in halls is better absorbed. The difference to trapezoidal sheet metal is clearly audible in direct comparison.

Comparison: Sound insulation trapezoidal sheet vs. sandwich panels

Criterion	Trapezoidal sheet metal (uninsulated)	Trapezoidal sheet + retrofit	Sandwich panels
Rain noise	Very loud	Muffled	Significantly quieter
Outside noise	Unhindered	Reduced	Significantly reduced
Machine noise (inside)	Reflected	Absorbed (partially)	Well absorbed
Reverberation	Long	Medium	Short
Installation effort	Low	High	Low
Room height	Maximum	Reduced	Maximum
Costs	Favourable initial	Expensive afterwards	Moderate, optimal in the long term
Sound insulation value	Practically none	Satisfactory	Good

Important: Sandwich panels are not acoustic panels for studios or recording studios. However, they offer significantly better everyday sound insulation than trapezoidal sheet metal - sufficient for most commercial and private applications.

Further technical details on the structure and properties can be found in our detailed guide to sandwich panels.

Conclusion: Planning noise-reduced buildings from the outset

Trapezoidal sheet metal offers practically no sound insulation. The thin sheet steel conducts sound instead of dampening it. Rain is loud, outside noise penetrates, machine noise reflects into halls. This does not matter for unheated warehouses without personnel - for all other uses it becomes a problem.

Subsequent sound insulation measures are possible, but are complex, expensive and never optimal. Acoustic panels, suspended ceilings and wall insulation are compromises with a loss of space and limited effect.

Sandwich panels offer significantly better sound insulation from the outset thanks to their absorbent insulating core. The multi-layer structure dampens rain noise, reduces external noise and improves the acoustics in production halls - without subsequent measures, without loss of space, without additional expense.

Our recommendation: Anyone who needs sound insulation - whether for employee comfort, noise protection requirements or quiet utilisation - should opt for sandwich panels from the outset. The investment pays off through better working conditions, happier staff and compliance with legal requirements. Let us advise you individually on the best solution for your project. Successful reference projects show noise-reduced buildings in practice.

Last updated Nov 2025