Tips for making a sound-insulating housing for appliances such as pumps, compressors and machines.

Step-by-Step Plan for Insulating Appliance Housings

On this page you will find our step-by-step plan for making a sound-insulating enclosure, or housing, for appliances and machines. You will find pictures and a review of a customer who has applied the step-by-step plan to his dental compressor. We have described the best product choice for you!

For which appliances and machines is this housing suitable?
The step-by-step plan for this sound-insulating housing is suitable for appliances and machines like compressors, jacuzzis, pool pumps, generators and more. This plan doesn't apply to heat pumps or outdoor air conditioning units. For these cases we would like to refer you to the tips page: “Insulating Outdoor Air Conditioning Units and Heat Pumps”.

Points of attention
To create a housing you need a construction plate, for example plywood, preferably as thick as possible. In order to insulate the housing, we recommend the following products:

  • Sound insulation
    In order to insulate noise, weight has to be added to the construction plate (plywood, etc.). We recommend an Isomat variant of at least 14 kg/m², the available variants are Isomat TS (purchases from 0.5 m²), Isomat KE (purchases from 5 m²). The following rule applies when it comes to sound insulation: mass = insulation. The heavier the Isomat, the higher the insulation value, the better the end result.
  • Sound absorption
    Sound absorption attenuates the sound inside of the housing, causing less noise to escape through ventilation openings or cracks. The two best and most economical options: Merfocell PU for appliances with an operating temperature of up to 80°C. Flamex GW for temperatures up to 150°C. For low-frequency noise, use a variant that is as thick as possible for optimal results.
  • Vibration insulation
    With a floating floor in the housing, the appliance is decoupled, reducing contact noise. Depending on the appliance/machine, overall the best options are as follows. Appliances up to 100 kg: 4 to 6 parts of Regufoam of 100 x 100 x 25 mm, type D220. Appliances between 100 and 200 kg: 6 to 8 parts of Regufoam of 100 x 100 x 25 mm, type D300.
  • Ventilation
    For appliances that need a supply of fresh air or cooling, two openings are necessary: to supply and discharge. In these openings you can apply the Aluphon damper(s). This is a silencer equipped with an absorbent inner jacket. Or you can integrate acoustic ventilation into your design, about which you can read more on our tips page "Step-by-Step Plan for Acoustic Ventilation". You need to determine how much air your appliance needs.
  • Mounting and sealing
    Contact adhesive, for mounting Isomat. Sikaflex, mounting and sealing kit. As for sealing seams and mounting, you need Regufoam.

Step-by-step plan for making the sound-insulating housing
As for making the housing, we have developped a short step-by-step plan. When designing the housing, pay attention to the aforementioned points of attention.

  1. Sheet material for the housing: In order to make the housing, use the thickest variant of concrete plywood or plywood (bottom layer). Choosing Merfoplex is a bit cheaper than purchasing Isomat and glue, and it takes less time processing Merfoplex. Make the housing spacious enough, preferably a bit bigger than exactly to size. There is als space required for the insulation material, maintenance of the appliance, and ventilation.

  2. Ventilation: Assume that your appliance or machine needs ventilation or at least needs to be able to dissipate heat, inquire the manufacturer to find out more about the details. We describe two options:

    • Ventilation option 1: acoustic ventilation.
      Below you can see a diagram of a DIY sound maze for the silent supply or removal of air. The sound maze contains baffles that create a labyrinth equipped with sound absorption material (Merfocell Nop is the most practical choice). Air and sound have to travel a long way along absorption material, making sure sound is 'filtered' out of the air. The sound maze can be integrated in the housing. You have to determine the dimensions yourself. The advice is a flow space through the sound maze of at least 125 x 125 mm and at least four baffles. Adding a fan causes the sound maze to stimulate the flow of air, which is certainly recommended when applied to compressors. You can also put cables through the sound maze, rendering holes in the sound-insulating housing unnecessary.


    • Ventilation option 2: Aluphon Dempers
      Aluphon dampers can be used if the appliance doesn't have ventilators. The same applies here: inquire your manufacturer in case of doubt. Use at least two Aluphon dampers, one for the supply and one for the exhaust of air. Hot air rises, so place at least one damper against the topside of the housing. Seal the edges that surround the dampers in order to prevent sound leakage.
  3. Apply sound absorption: Equip the entire housing on the inside with absorption material. We have pre-selected the best product for you: the thickest variant of Merfocell PU or Flamex GW. Like with the insulation mat: the thicker is, the better. The difference in decibels may be as high as 5 dB, whereas the price difference is only a few euros. Apply the absorption material without seams. Both products are easy to cut to size with a hobby knife, and no glue needed since both are self-adhesive.

  4. Floating bottom: Appliances that contain parts that move can cause the outside of the housing to vibrate, resulting in a big sound leak. By placing the appliance on a floating, double bottom (preferably fixed) this can be avoided. Place blocks of Regufoam of about 100 x 100 x 25 mm under a sheet of plywood (or something similar), and put the housing on top of it. The amount and type of Regufoam depends on the weight and type of appliance. In general, you can use the following information as a guideline, keeping in mind that the appliance needs to be stable, and that the floating bottom is not allowed to touch the walls: 0 to 100 kg at least 4 to 6 parts of 100 x 100 x 25 mm, Regufoam D220, art. No. M0719. 100 to 200 kg at least 6 to 8 parts of 100 x 100 x 25 mm, Regufoam D300, art. No. M0718.

  5. Sealing: The sealing of the housing is just as important as the insulation. Caulk the seams and cracks and seal the access hatch well, possibly by means of a draft band or a piece of rubber in combination with toggle latchers (to be provided yourself).

The end result in practice
By applying this solution, depending on the source of the noise, a sound attenuation of no less than 20 decibels is feasible. Many customers perceive this as a reduction of at least 50% of the noise. This is quite a reduction, which is especially appreciated if you use the solution to reduce nuisance to neighbours or the surrounding environment. One of our customer has successfully applied this solution to his dental compressor. His satisfaction with the end result is reflected in his reaction:

Some time ago you gave me advise about how to insulate a dental compressor. In the meantime, I have placed the housing. The first photo shows the initial situation. The meassured volume was 70 dB. The second photo shows the plywood sheets covered with Isomat KE. In order to allow for disassembling, I mounted the plates with wing nuts. The base plate is placed on Regufoam and the compressor on 2 concrete tiles of 30 x 30 cm. The third photo shows how the plates are set up. In the fourth photo they have been partly provided with Merfocell PU. The damper is placed on the left and on the right the fan (originally intended for bathroom venting). For easy accessibility, this plate can be removed quickly with so-called toggle latches.

The volume has been reduced to 50 dB. The heat dissipation seems sufficient but needs to be further tested in hot weather. A damper for the intake seems unnecessary for the time being. Due to lack space, the housing has become slightly smaller than I intended. At first glance, the mission seems to have succeeded and I am satisfied with the achieved result.

Do you have any questions about this topic? Please feel free to contact us, we will be happy to answer your questions as soon as possible.