Guide on how soundproof a door

How to soundproof a door, soundproofing for an existing door
A normal room door in a house, office or waiting room might need soundproofing because these doors generally have poor soundproofing properties, both speech and music can be an issue. This is due to the lack of mass (weight) in the door leaf and poor sealing in the doors frame and often a gap between the door and floor, especially when a sill is missing.

The solution for soundproofing a door
Soundproofing a door is relatively simple. Make the door (door leaf) as heavy as possible by soundproofing the door with Isomat TS, a mass loaded vinyl, and ensure a good sealing. The step-by-step plan below explains the method for to soundproof a door.

• Step 1: Preparing the door
  Soundproofing a door is easiest when you take the door out of the frame. Place the door with the side that needs to be insulated upwards. Depending on the type of Isomat you will apply and the number of layers, the door will weigh at least 8 or 14 kg per square meter more. So, additional hinges might be added to keep the door tightly closed and safe. Make sure the door has at least four hinges, but five hinges are preferable when using the heaviest Isomat.
   
• Step 2: Prepare and apply Isomat
  Now that the extra hinges have been installed, you can cut the Isomat plates to size with a sharp knife. The entire door leaf has to be equipped with Isomat TS8 or TS14. Once you have customised the Isomat, you apply contact adhesive to the Isomat and the door, leave it for about five minutes. After this, you can attach the Isomat to the door. Make sure to press it firmly in order to avoid air bubbles. The curing of the glue takes about twelve hours in total, so we advise to secure the Isomat on the long sides with three screws, totalling six screws per sheet. Make sure you have sufficient ventilation during this process!
   
• Step 3: Finishing Isomat
  Isomat is an industrial product and needs to be finished. Ideally, this is done by applying a sheet of plywood to the Isomat. Pay attention to the thickness of this material, so that you do not get into trouble with a door that suddenly happens to be too thick at the side of the hinges. Provide a sheet of plywood that is the same size as the door leaf and glue and screw it into the Isomat. Then paint the wooden sheet with a colour of your choice. In this way, you can't see the Isomat, a practical tip for rental properties. The type of wood is irrelevant with regards to acoustics.
  
  
• Step 4: Sealing seams and cracks
  A well soundproofed door also has to close of well. High-frequency noise can easily pass through small cracks between the door and frame and underneath the door. Mount a door rubber in the frame and sill to avoid sound leaks. If there is no sill available you should install a ‘EllenMatic Drop Seal’. A drop seal closes the gap between the door and the floor, preventing sound leakage and drafts across the floor.

Soundproofed door with Isomat TS Mass Loaded Vinyl

Customer review
We received the following response to the step-by-step plan from a satisfied customer:

I just wanted to let you know that we are very satisfied with your insulation plan. Due to business only a draft strip and brush were applied at the bottom of the door. This only helped a little bit. We ordered and placed the materials a few weeks ago. Now a few months have gone by, and I dare to say that the sound has decreased by 75 percent. I'm very satisfied!

Please note
Doors with a steel door frame, often only containing two hinges, should be equipped with maximally one layer of Isomat TS 8 kg/m², not the heavier type TS 14. This type of door is not that sturdy and usually cannot be equipped with additional hinges. It is better to replace these types of doors with a heavy door and wooden door frame, as the frames themselves may also leak a lot of noise.

Required soundproofing products

• Isomat TS
  Isomat, we recommend the 14 kg/m² type.
• Contact adhesive
  For double-sided application. One spray can per door.
• Elton EllenMatic
  Drop seal, for a perfect closing door.

To be purchased elsewhere

• Plywood as finishing products.
• Screws with a flat head, six per Isomat sheet.
• Lacquer for finishing the plywood sheet.

Soundproof Studio Doors
In some cases it's better to replace the door all together with complete new soundproofing door. For example when a soundproofing of 42 plus decibels is need, in a recording studio, TV studio or for industrial applications for instance. From our factory, Merford Special Doors, in the Netherlands, we can offer special doors with very high soundproofing properties up to 55 dB(a). Some examples:

• Wooden Door MH 42.
  Complete set including a heavy wooden door, mounting materials, built-in drop seal and steel door frame, soundproofing properties: 42 dB(a).

• Steel Door SD47.
  Complete set including a steel door, mounting materials, pre-mounted steel frame, door handle, lock with three keys, double built-in drop seal, soundproofing properties: 47 dB(a).

Questions? 
Do you have any questions about soundproofing doors or complete door sets? Please feel free to contact us, we are happy to help you.