Graphical Construction Glossary >> Doors. >> Door types >> Acoustical Door

Acoustical Door
A solid door constructed to reduce noise transmission. It normally has gaskets around the top and sides and with an automatic door bottom. A door that has an STC rating
Sound Transmission Class (STC)
A rating system to measure sound transmission
Automatic Door Bottom Seal
A moveable strip inset into or face fixed to the bottom of a door that drops down automatically when the door is closed to seal off draughts, moisture or sound.
Lift Hinge
A butt hinge that has a bevelled interface between the leaves that causes the door to lift up as it opens.

auto seal and threshold
An automatic door bottom seal in combination with an aluminium threshold.
Image provided by Hafele Australia Pty. Ltd.

Many buildings such as schools and their music rooms, hotels and conference centres benefit from having modern methods of containing sound. Ceilings and walls are built to SEC ratings and so are doors. Many solid timber doors in themselves have excellent sound ratings and others of hollow construction require filling with mineral fillers. For a swinging door to work efficiently it has to have clearance around it's perimeter and it is that clearance that can leak sound etc though the door and frame unit.

With modern frame it is normal to see brush seals or neoprene strips to the top and sides. However the bottom of a door is a special case.

  • Any type of fixed seal down from the bottom of a door soon gets abraded with the action of the door, and so they soon stop functioning. With seals like in the photo above the seal itself does not touch the floor or threshold until the door is almost closed.
  • The working part of the seal is held in the retracted position until the small button is pushed in when it makes contact with a door jamb.
  • The button in the above photo would be on the hanging side but the buttons below the the bevelled faces are activated by the lock jamb.
bottom sealsbottom seal face fixed
A seal fitted to a groove in the bottom of the door. A seal that is fixed to the face of the door.
Images provided by Hafele Australia Pty. Ltd.

There are a large range of fitting that do this job of sealing the bottom of acoustical doors. Some are fairly generic and they can work of different doors and others are designed for specific door types. For instance there are ones that suit all glass doors and there are others that work well with sliding doors.

lift hinges
A lift hinge.
Image provided by Hafele Australia Pty. Ltd.

What you see here is a lift hinge. So if we had a fairly generic seal to the bottom of a door that uses these hinges, then it is easy to see that instead of the seal lifting to save wear and tear on it, we can get the same effect with these which lift up the whole door as it opens.

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Please Note! The information on this site is offered as a guide only!  When we are talking about areas where building regulations or safety regulations could exist,the information here could be wrong for your area.  It could be out of date!  Regulations breed faster than rabbits!
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