A genset room in an industrial facility is not an ordinary room. A 100 to 250 kVA genset operating inside an enclosed space produces 95 to 110 dB measured one meter from the unit. Indonesian labor regulations set an exposure limit of 85 dB for an eight-hour shift. That gap is not a comfort issue. It is a legal compliance and worker safety issue.
Why industrial genset rooms are harder to isolate than standard office spaces
A noisy office presents one type of problem: airborne sound traveling through walls, ceilings, or doors. That is relatively well understood. The fix involves adding mass to walls, applying absorptive material, and sealing gaps.
An industrial genset produces two types of noise simultaneously. The first is airborne noise, as described above. The second is structure-borne noise: vibration that travels directly through the foundation, concrete floor slab, and building frame into the rest of the building. That vibration does not care how thick the genset room walls are. It moves through the structure itself, not through the walls.
This is why many genset room projects disappoint clients even when carried out by experienced general contractors. A contractor experienced in office fit-outs or recording studios builds layered walls, hangs a heavy door, and signs off the job as complete. The result: airborne noise drops, but vibration on the third floor is still felt. Complaints come from upper-floor occupants, and the client pays again for work that should have been done at the start.
It is also important to note that the decibel reduction achievable on any project cannot be separated from the existing construction. Thick concrete walls already in place give a very different starting point than thin brick partition walls. Without a site survey, any reduction figure a contractor quotes is a rough estimate that cannot support a contract.
The difference between acoustic treatment and sound isolation for a genset room
Acoustic treatment works inside a room to reduce reflections and reverberation, so sound is cleaner within that space. Sound isolation prevents noise from leaving through walls, floors, and ceilings into adjacent spaces. An industrial genset room needs sound isolation, not acoustic treatment. A contractor who uses both terms interchangeably is almost certainly specifying the wrong scope. Choosing a proposal in the wrong category is the most common reason final results fall well short of the target.
In practice, this confusion often originates in the client brief. A facility manager writes “genset room soundproofing” but means full isolation to the outside. One contractor proposes absorptive panels on the interior walls. Another proposes a double-wall construction with heavy-mass layers. The two quotes cannot be compared directly because the scope of work is fundamentally different. Make sure both the brief and every proposal use the same term: sound isolation, not acoustic treatment.
The correct construction sequence for genset room isolation, from foundation to ventilation
This sequence is not a matter of preference. It follows the physics. Skipping or reversing any step changes the outcome significantly.
- Anti-vibration mounts and floating floor. This is the first task, before any wall material goes up. Anti-vibration mounts are fitted beneath the genset unit to break the direct vibration path to the concrete slab. The floating floor, a floor layer that “floats” on rubber or spring isolators, is built after the mounts are in place. If the floating floor is built after the walls are finished, working space is restricted and the result is suboptimal.
- High-mass layered walls. The governing principle is mass law: the heavier the wall per unit area, the greater the airborne sound reduction. A combination that works is a first layer of brick or concrete, followed by high-density Rockwool at a minimum of 60 to 80 kg/m3 as the absorptive layer, then closed with multiple layers of gypsum board. An air gap between layers adds further reduction. A single wall, however thick, does not perform as well as a double wall with an absorptive-filled cavity.
- Double acoustic doors. The door is consistently the weakest point in the construction, and consistently underestimated. A single standard door, even a heavy one, can surrender 10 to 15 dB of hard-won wall performance at a single point of leakage. Double acoustic doors with door seals on all four sides and no gap at the bottom are the minimum standard for an industrial genset room.
- Baffled ventilation. A genset requires a large volume of incoming air for combustion and cooling. Blocking that airflow is not an option. The solution is an acoustically baffled louvered duct that keeps airflow unrestricted while breaking the straight-line path that sound travels through. Without correct acoustic ventilation design, all the wall and floor work will not reach the target because sound exits through the path left open.
- Exhaust silencer. The exhaust pipe carries noise out through a path entirely separate from the walls. Without a silencer on the exhaust duct, engine noise exits at the pipe outlet and re-enters the surrounding environment. No wall system, however well built, can address that path.
For a full picture of the work scope and technical specifications that can be referenced in project documents, see the genset room and AHU room sound isolation service page.
Materials for genset room walls and ceilings in industrial settings
For an industrial genset room, material selection must account for acoustic performance and fire resistance together, because a genset is both a heat source and a fire risk. High-density Rockwool at 60 to 80 kg/m3 is the primary choice because it absorbs airborne sound and carries an adequate fire rating. K-Flex is used for high-temperature exhaust pipe insulation. Glasswool can be used in dry areas without direct heat exposure. Aluminium foil is fitted as a vapor barrier in high-humidity environments. Do not select materials based on price per square meter alone.
Material-by-material considerations:
- Rockwool 60 to 80 kg/m3: This material combines sound absorption and fire resistance in a single layer. Density below 60 kg/m3 produces significantly less absorption, particularly at the low frequencies that dominate diesel genset noise. See the high-density Rockwool specifications for genset rooms to select the right product for your project’s acoustic load.
- K-Flex: Used specifically for exhaust pipe and high-temperature duct insulation. It withstands heat levels that would damage standard glasswool. Full specifications are on the K-Flex page for high-temperature exhaust pipe insulation.
- Glasswool: An alternative in areas not exposed to direct heat and in dry conditions. It is lightweight and straightforward to install, but cannot be used near heat sources such as exhaust pipes without additional protection.
- Aluminium foil: Fitted as a vapor barrier, particularly in basement genset rooms or any area with high ambient humidity. Moisture that enters the Rockwool or glasswool layer significantly degrades the material’s acoustic performance over time.
The reference standard for HVAC and acoustic ventilation design in mechanical rooms is the ASHRAE Handbook: HVAC Applications.
Mistakes we find repeatedly when fixing genset rooms that were already built
Remedial work on a genset room almost always costs more than getting it right the first time. These are the four mistakes we encounter repeatedly in the field:
- No anti-vibration mounts fitted. The walls are solid, the door is heavy, but occupants on the third floor still feel vibration through the floor when the genset runs. Vibration has traveled through the foundation into the building columns and up through the entire structure. The fix requires lifting the genset unit temporarily to fit mounts beneath it, an extra cost that was not in the original proposal.
- Ventilation left straight with no baffles. The result of this mistake is immediately measurable: genset noise exits in full through the air path even though the walls were built with expensive material. Contractors who do not understand acoustic ventilation tend to leave the air path as-is on the basis that “the genset needs air.”
- Low-density material selected to reduce cost. Rockwool at 32 kg/m3 is cheaper than Rockwool at 60 kg/m3, and some contractors specify it without explaining the performance difference. The client receives a proposal that looks complete on paper but delivers a decibel reduction well below the target. Demolition and rework costs more than the material saving it was based on.
- Single standard door with a gap at the bottom. A two-centimeter gap under the door is sufficient to pass mid and high-frequency sound freely. A door without automatic door seals cancels the effect of the entire surrounding wall at that point.
If your facility has a control room adjacent to the genset room, the acoustic requirements are different. Read more about control room acoustics to understand the different approach needed.
How the survey and project proposal process works
The initial survey for projects within the Jabodetabek area is free of charge. The team visits the site to measure existing noise levels, assess the current condition of walls and floors, and identify existing sound leakage paths before any construction begins. Design work and technical consultation are also included at no separate charge.
For projects outside Jabodetabek, mobilization and accommodation costs are stated openly in the quotation and are not embedded in other line items. Before an on-site visit is scheduled, an initial technical discussion can be held via video call to assess project feasibility and prepare more focused survey questions.
Our proposals specify materials layer by layer, the construction sequence, an estimated decibel reduction based on the planned construction, and the conditions assumed. The decibel reduction figure in a proposal is a calculation based on survey measurements and the specified materials, not an unsupported claim.
After-sales service covers periodic checks for six months after handover, with a one-year workmanship warranty. As a reference project that can be reviewed, our team has completed the Ministry of Defense genset room project, which can serve as a benchmark for scope of work and the specification standards we apply.
When work can start and how long it takes
An active genset room cannot be worked on at any time. A genset serving as the building’s backup power source typically cannot be shut down during operational hours. Work phases that require the unit to be offline, particularly anti-vibration mount installation and floating floor construction, must be scheduled during routine genset shutdown windows or on weekends.
Heavy materials such as brick or concrete for the high-mass walls require access through the goods lift, and the goods lift schedule must be coordinated with building management well before materials arrive on site. This is not a constraint that can be ignored. Delayed material access shifts the entire project schedule directly.
For a genset room of 20 to 40 m2 using double-wall construction with a floating floor, the typical duration is two to four weeks including material curing time. Larger rooms, or rooms with restricted access, require their own estimate. A duration figure stated without conditions attached cannot be used as a basis for project planning.
FAQ: Technical questions from facility managers
What is a realistic decibel reduction for an industrial genset room?
The achievable reduction depends on the existing wall construction, room volume, and the methods used. A genset room with existing thick concrete walls, fitted with a floating floor, baffled ventilation, and double acoustic doors can typically achieve a 25 to 40 dB reduction from the baseline. That figure must be calculated per project from survey measurements, not assumed from an average. Any contractor who quotes a number before visiting the site should be asked to explain their methodology.
Does the genset need to be shut down during installation?
Not for the entire duration, but certain phases do require the unit to be offline, particularly when fitting anti-vibration mounts beneath the unit and when finishing the interior under safe working conditions. The work schedule is normally planned with building management or the facility manager to align with routine genset shutdown windows or weekend slots.
Can genset room ventilation be preserved after sound isolation is installed?
Yes, and this is one of the most critical parts of the design. A genset requires a large volume of incoming air for combustion and cooling. The solution is an acoustically baffled louvered duct that keeps airflow unrestricted while breaking the straight-line path that sound travels through. Without correct acoustic ventilation design, all the wall and floor work will not reach the target decibel reduction.
The isolation is installed but vibration is still felt on the upper floors. What went wrong?
Vibration felt on upper floors is a symptom of structure-borne noise that was not addressed. If the work focused only on walls and no anti-vibration mounts were fitted beneath the genset unit, vibration continues to travel through the foundation into the building structure. The fix is to add a floating floor or anti-vibration mounts as supplementary work, at a higher cost because the genset unit must be lifted and temporarily repositioned.
What warranty applies to genset room sound isolation work?
Dewa Peredam Ruangan provides a one-year workmanship warranty and six months of after-sales service including periodic checks. Any sound leakage detected within that period caused by work we performed is remedied at no additional charge. The warranty applies as long as no structural changes or additional machine loads are introduced by other parties after handover.
Can projects outside Jabodetabek be handled?
Yes. Our team has completed projects outside Jabodetabek. Mobilization and accommodation costs are stated openly in the quotation and are not embedded in other line items. The amount depends on distance, project duration, and the number of personnel required on site. For projects outside Jabodetabek, the initial survey can begin with a technical discussion via video call before an on-site visit is scheduled.
Next steps
A genset room with an existing noise problem does not become easier or cheaper to fix over time. Remedial work on a job done incorrectly consistently costs more than doing it right from the start. Indonesia’s occupational noise exposure regulations are referenced in the ILO publication on occupational safety, and compliance is not optional in an industrial facility.
If the genset room at your facility does not yet meet the noise standard, or if previous work did not deliver the reduction required, our team is ready to survey the site and provide a written proposal based on actual site conditions. Request a free survey for your genset room and we will schedule a team visit to your location.