Chiltern International Fire Engineer Andrew Forecast comments on upgrading fire doorsets and stresses that it is vital to look at each case individually.
A fire resisting doorset is designed to function both as a door and as a barrier to a fully developed fire in a building. Although any closed door will have some delaying effect on the development and spread of a fire, a fire door must be proven to be capable of resisting the effects of a standard fire test for stipulated periods, usually 20 or 30 minutes.
Understandably, the requirements for fire doors are complex. While representative examples of intended fire door designs are required to be tested to BS 476-22: 1987 Methods for determination of the fire resistance of non-load bearing elements of construction, or to BS EN 1634 – 1: 2000 Fire resistance tests for door and shutter assemblies, this is rarely if ever feasible for doorsets upgraded in situ. In most cases regulatory authorities are willing to accept an assessment of likely performance in lieu of a test result.
Chiltern Fire would argue that it is often preferable – and safer - to install new and third party certified doors when refurbishing or upgrading the passive fire protection within existing buildings.
That said, there are circumstances where it is necessary to retain the existing door, for example to comply with fire regulations when the use of the building has changed. Upgrading might also be considered to meet either retroactive legislation or new insurance requirements.
In such cases, existing doorsets may be upgraded to achieve the required fire resisting performance, but it is vital to look at each case individually. The existing doorset installation and the condition of the leaves and the frame will vary from building to building. We recommend that building owners/managers consider the following checklist when deciding whether to upgrade or to install new fire doorsets.
Checklist for upgrading
- Is it worthwhile to upgrade or is a replacement a more effective alternative?
- What level of fire resistance is required?
- Will an upgraded solution satisfy the control authority?
- Has each existing door leaf and frame the potential for being upgraded?
- Has the method of improving the burn-through resistance of the door leaf been proven and does it need assessment by a specialist?
- Has the door frame gap been upgraded in terms of fit, intumescent protection and smoke sealing?
- Is the frame adequate and sufficiently well sealed into the wall?
- Is the ironmongery appropriate for use on a fire resisting doorset?
There is no ‘one size fits all’ method of upgrading and the solution chosen will depend on the door construction, condition, situation and customer requirements. In our experience, several methods have proved effective, such as facing the door leaf with a non-combustible board.
For panelled doors, the weakest area is generally the panel itself – in many cases the timber can measure less than 10mm at the thinnest point. One method of upgrading is to remove the panel, split it through its thickness and insert a sandwich material, either an intumescent sheet or a non-combustible board. Although more labour intensive than other approaches, this does enable the original finish to be maintained.
In addition, intumescent paper and card can be used selectively to protect vulnerable areas and can be veneered to restore the timber finish.
There are currently no requirements for upgraded fire doors to be marked in any particular way. However, when care has been taken to undertake a sympathetic upgrading, it would seem a wasted effort if at a future date it were not possible to identify that this work had been carried out to a certain level. Chiltern Fire would recommend that some method of permanent identification should be used to enable approving authorities to identify that the doorset has been upgraded long after the work has been carried out. A sticker on the leaf head, stating for example the integrity performance, survey report reference number and the date of the upgrade, could be used.
rss feeds
