Not every construction project is satisfied with the statutory minimum sound insulation. Anyone planning or contractually agreeing to higher standards needs to know which standards apply, what values must be met, and which door classes can meet these requirements.
Standard vs. enhanced soundproofing – what’s the difference?
The DIN 4109 standard, “Sound insulation in building construction”, sets out the minimum requirements in Germany that must be met for all new buildings and any significant alterations. These values are legally binding under building regulations and apply automatically – without the need for them to be specifically mentioned in the contract.
Enhanced requirements go beyond this. They are based on DIN 4109-5 “Sound insulation in building construction – Part 5: increased requirements” and apply only if they have been contractually agreed between the client and the contractor. They are therefore not a legal standard, but a quality feature that is deliberately chosen – and which has a noticeable impact on comfort, privacy and the market value of a property.
DIN 4109-5: What exactly does it cover?
DIN 4109-5 was last published in August 2020 and defines sound insulation values that are 5 dB higher than the standard requirements of DIN 4109. It applies to all sound insulation components in building construction – not just doors, but also walls, ceilings and staircases. The standard is particularly relevant for doors, as even small differences in sound insulation class determine the level of comfort that can actually be achieved.
Important for planning: The increased requirements must be explicitly stated in the building contract or the specifications. In the absence of such an agreement, the standard requirements of DIN 4109 automatically apply – even if the client subjectively expected a higher standard.
What dB levels apply in cases of stricter requirements?
Occasionally, ‘enhanced’ sound insulation requirements are imposed on doors. These enhanced requirements apply where they have been contractually agreed and are based on the sound insulation values set out in DIN 4109-5 ‘Sound insulation in building construction – Part 5: Enhanced requirements’.
If the standard requirements apply, 27 dB or 37 dB must be achieved – depending on whether the door leads into a closed hallway or directly into the living area. If the hallway is only partially open, the 37 dB requirement also applies. If the increased requirements must be met, the doors must achieve 5 dB more in each case: i.e. 32 dB or 42 dB.
When are stricter requirements agreed upon?
Stricter requirements are not a niche issue – they are more common in practice than one might think. Typical areas of application include upmarket residential developments, where developers or architects wish to offer a noticeable quality advantage over the minimum standard. Office and administrative buildings with confidential areas – such as meeting rooms, staff offices or executive suites – also benefit from higher standards. The same applies to healthcare buildings such as clinics, doctors’ surgeries and care homes, where privacy and tranquillity directly contribute to the quality of care.
In apartment blocks targeting a discerning clientele, these higher standards are increasingly being used as a selling point. Any developer or investor promoting ‘greater peace and quiet’ should enshrine DIN 4109-5 as a contractual basis – this is the only way to ensure the standard is legally binding.
Which sound insulation classes meet stricter requirements?
The stricter requirements of DIN 4109-5 specify the following minimum sound insulation values for doors:
For doors leading from a hallway or stairwell into a flat with an enclosed entrance hall, a required construction value of R'w 32 dB applies. This corresponds to our sound insulation class SK2 (factory value Rw,P ≥ 37 dB).
For doors leading directly from the hallway into the living area – i.e. without an antechamber – an increased construction value R'w of 42 dB applies. This corresponds to our sound insulation class SK3 (factory value Rw,P ≥ 42 dB).
As a rule of thumb: if you wish to meet higher requirements, always plan for a sound insulation class one level higher than the standard. And: the factory value of the door element must always be 4–5 dB above the required construction value to compensate for installation losses.
Planning: What do architects and clients need to bear in mind?
Higher sound insulation requirements place greater demands on the entire system – not just the door leaf. The following points are crucial during the planning stage:
Ensure contractual coverage: The increased requirements under DIN 4109-5 must be explicitly stated in the specifications or the building contract. Without a contractual agreement, only the standard requirements apply.
Select a tested complete unit: Only the door leaf and frame as a tested system can reliably achieve the declared value. Combining individual components from different sources jeopardises the test certificate.
Distinguish between factory-measured value and installed value: Always clarify in the tender whether the required value is meant as a factory-measured value (Rw,P, laboratory value) or as an installed value (R'w, installed). The difference is typically 4–5 dB.
Take flanking transmission into account: Secondary sound paths via walls, floors and installations can reduce the actual insulation performance achieved once installed. Careful detailed acoustic planning is essential where requirements are higher.
Ensure professional installation: Correct adjustment of the floor seal, hinges and connection joints is essential to ensure that the door unit actually achieves its declared value once installed.
Are you planning a project with enhanced sound insulation requirements? Our soundproof doors in classes SK2 to SK4 are certified complete units in accordance with DIN 4109 and also meet the enhanced requirements of DIN 4109-5.