A plaque in my office bears the inscription: “People who think that they know everything, annoy those of us that do.”
It’s an adage that I often refer to when I am debating an issue with someone who is clearly wrong. It’s not so easy when you have to turn it on its head and admit that perhaps you don’t know absolutely everything and perhaps sometimes (albeit very rarely) you may not be the font of all knowledge. Well, this is a position that I have been put in over the past couple of months over an issue that I raised with you back in December 2007 in respect of the use of fire doors in dwellings.
FIRE DOOR RATINGS
Approved Document B 2006 refers to the use of FD20 fire doors where they form part of the enclosure to:
- A protected stairway in a single family dwelling house, whether new build or formed as part of a loft conversion or extension
- A protected entrance hall or protected landing in a flat.
In the past, timber fire doors that met the FD20 period of fire resistance when subjected to an appropriate fire test method were widely available. It was common for a door to be rated FD30 when installed with intumescent seals and rated FD20 when installed without intumescent seals.
However, FD20 doors are no longer available under independent certification schemes. The minimum rating of a fire door is now predominantly FD30, with intumescent seals being necessary to achieve this rating. This change has came about in recognition that very tight edge gaps were necessary to achieve a FD20 fire rating when doors were subjected to fire resistance testing without intumescent strips. Certifiers of fire doors were concerned that these edge gap tolerances would prove impractical and that the edge gap dimension was unlikely to be maintained over the service life of the door.
BCA GUIDANCE NOTE ON FIRE DOORS
In 2007 I wrote in support of the use of fully tested FD30 doorsets with intumescent strips to be used as a whole and for the intumescent strips to remain in place. However, following work carried out by the Building Control Alliance (BCA) Technical Group which represents both public and private sector building control bodies I have changed my view and I am pleased to say that the BCA has recently issued a guidance note on Fire Doors in Dwellings. The guidance recommends that where a FD20 fire door is required, FD30 door leaves that have been tested as part of a set incorporating intumescent edge protection would be acceptable when installed with or without intumescent edge protection. If the intumescent strip is to be omitted, care should be taken to ensure that edge gaps to the Jambs and head of the door are no more than 4mm and the gap at the bottom of the door should be restricted to maximum of 22mm from an unfinished floor and a maximum of 10mm from a finished floor.
Additionally, cold smoke seals are not required to be provided to doors used in these situations but where they are fitted, they do not need to be removed. Whilst I agree that this practice may not be directly supported by an appropriate fire test or independent certification, as contended in my earlier column, this method of installation has been widely accepted by the construction industry and building control as providing sufficient protection to escape routes within dwellings.
Therefore it is with a heavy but joyous heart that I will now change my plaque to read “People that think they know everything, may sometimes be right, and so may only annoy those of us that do some of the time”.
