Although the value of draught-proofing doors and windows is now widely accepted, the benefits of sound-proofing doors and windows are less widely understood. Even so, noise pollution is set to become one of the most serious problems facing Britain over the next twenty years according to 63% of people asked in the British Social Attitudes Survey (1995). The BRE found that the primary causes of complaint included noisy neighbours, children crying, traffic, aircraft and trains. The spread of powerful stereos and TVs together with the pressure to build more units in the available land space has exacerbated the problem. The dramatic rise in complaints about noisy neighbours to Environmental Health Offices has led some London Boroughs to establish dedicated hotlines outside office hours.

We worked with the BBC’s Chief Architect (Keith Rose) to develop the best options available to soundproof the BBC’s studio and auditorium doorsets. Every few days, Keith visited our Technical Experts and took away more samples to fit and test. For each new combination, he measured sound transmission through the doorset around each part of the construction. After months of testing, he found that the best solution was to use fridge magnets to seal the top and sides of the door leaf to the frame plus a combination of Sealmaster’s Thunder threshold seal with a hardwood strip fixed to the threshold itself.

However, because the BBC needed to wheel a great deal of machinery through these doorsets, frequent wedging of the doors to keep them open weakened the fixings of the surface mounted Thunder threshold sections. So they were reversed – and rebated flush with the bottom of the door to make them considerably more rubust when wedged frequently (see Thunder TMS/WHS). As a result, the BBC adopted the solution for all of its doorsets in recording studios and auditoria. Further details on this and other acoustic dampening designs can be found in Keith Rose, Guide to Acoustic Practice, (2nd edition), 1990 published by BBC Engineering.

When evaluating claims about the acoustic performance of a doorset, seals, etc. it is important to note whether the data are based on tests using an operational door or a fixed panel of similar construction. Fixed panels can give impressive results but are very unrepresentative of what can be achieved with operational doors.

To illustrate the difference Sealmaster acoustic seals can make, we put two solid core fire doors (often used where a performance of 30-35dB is required) to independent test - one 44mm and one 54mm thick. As a fixed panel, the 54mm door achieved 31dB but as an operational door this fell to 23dB. The 44mm door managed 32dB as an airtight panel but only 20dB as an operational door. With the addition of the correct seals, up to 95% of this loss in performance was redeemed. In its operational configuration, the sealed 54mm door achieved 31dB and the 44mm door obtained 30dB.

The precise performance of any given door or window will depend upon a variety of factors. For example, single doors perform better than double doors. Solid core doors will do better than hollow ones and if a keyhole or threshold gap is left unsealed, performance can be significantly undermined.


The range of acoustic seals and their applications is shown below.