Acoustic, smoke & fire containment systems

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Sound Systems - 2005

Approved Document E to the Building Regulations (England & Wales) covers acoustic conditions in “dwelling-houses, flats and rooms for residential purposes” – including specific requirements for door assemblies. Phil Cavalier, Specification Manager for Lorient, examines recent regulatory changes which affect doors, and how an integrated systems approach is essential to meet the requirements.

In July 2003, amendments to Document E “Resistance to the passage of sound” came into effect, and the implications of this are now being seen in earnest throughout the industry. While much has been written about “robust details” relating to walls and floors, a vitally important part of the building deserves equal attention – the doors.

By their very nature, doors require special consideration. Gaps are required around the perimeter of a door, and at the threshold, to allow its normal operation – gaps which, unsealed, will allow air, sound and smoke to pass through. Thus doors can often by seen as an unwelcome, albeit necessary interruption in an acoustic wall.

In Document E, the issues of duty of care and quality of life in residential premises have now been reinforced by regulatory requirements. Sections 2.2.6, 4.20 and 6.6 of Document E give specific guidance:

“Ensure that any door has good perimeter sealing (including the threshold where practical) and a minimum mass per unit area of 25 kg/m2 or a minimum sound reduction index of 29dB Rw (measured according to BS EN ISO 10140-1: 2010 and rated according to BS EN ISO 717-1:1997). The door should also satisfy the Requirements of Building Regulation Part B – Fire safety.”

This will affect doors in numerous situations, both for new build and “material change of use” projects – including apartment entrance doors, and rooms in halls of residence, hotels and care homes.

Satisfying Document B is the first consideration, as only a fire rated door assembly, with test evidence for both fire and smoke containment, will meet Document B and BS 9999 requirements (an Approved Document for compliance with Building Regulations). An essential part of such a door assembly is an intumescent fire seal around the perimeter of the door, often incorporating a smoke seal. For the majority of fire rated doors, smoke sealing has long been a requirement, and a traditional brush-style seal is frequently used. However, a typical FD30 door assembly, fitted with a brush smoke seal, has been proven to offer acoustic performance of only 23dB Rw - well below the 29dB Rw Document E requirement. So although such a door assembly may meet the requirements of Document B, clearly this will not be sufficient to satisfy Document E.

However, superior performance can be achieved by using an elastomeric blade-type smoke seal. This can either be as part of a combined fire and smoke seal (such as Lorient’s new DS seal); or a separate “retro-fit” seal, such as the Lorient Batwing®, ideal for upgrading existing fire rated doors for smoke and acoustic performance. Both the DS and Lorient Batwing® have been tested on typical fire rated door assemblies, and have been proven to provide 31dB Rw, when used with a recommended threshold seal, such as Lorient’s IS8010 si. A threshold plate also helps, by providing a solid surface so the seal makes good contact.

Threshold sealing presents an interesting issue: the wording “where practical” in Document E would suggest that if this cannot easily be achieved, it may be omitted. However, this creates a conflict within the requirements. Extensive testing has proven that without a threshold seal, the minimum 29dB Rw rating cannot be achieved. In a fire, an unsealed threshold also provides a straight-through gap for smoke. Thus both BS 5588 and Document E requirements mean that threshold sealing is not optional, but essential.

While meeting all these requirements, another Document must not be overlooked – Document M , “Access to and use of buildings”, which also presents requirements for doors. In addition to detailing door width and threshold height, Document M requires that doors be easy to operate, to present a minimum barrier to access. While door closers clearly play an important part here, the smoke and acoustic seals must not detract from the performance of the door assembly by creating friction. Once again, elastomeric blade-type seals present the optimum solution - for example, the Lorient Batwing® has recently been re-engineered with curved fins, dramatically reducing the effort required to open the door.

By taking an integrated approach, meeting all the requirements need not become an onerous task. By carefully selecting containment systems that demonstrate all-round performance, it is possible to meet the requirements in any situation, while making a positive contribution to quality of life, and life safety.

For information on Lorient’s CPD seminars, covering acoustic, fire and smoke containment, contact Lorient on 01626 834252.