Loft Conversion fire door regulations

[Stretch]

Hi,
I am puzzled by the current requirements for fire doors as a result of adding a loft conversion. Standard 5 year old det house. New staircase planned to loft space which will lead to a new landing and 2 rooms.
Regulations (2006, in force April 2007) apparently say that fire retaining doors must be fitted to all ground and first floor rooms that lead off of the landings / hall (presumably the escape route).

I have mains/batt smoke detectors on the landing and hall. If I keep the doors all closed and a fire broke out in a room off of the hall, would the door keep the smoke in the room for some time, so the hall smoke detector would not go off? If so this would prevent any alarm being raised until the door was about to fail - too late. It seems far more logical to keep the doors open and fit smoke detectors in all rooms, allowing the alarm to sound as quickly as possible. What do you think?

Secondly, I have been told that many people replace their current 35mm doors with similar sized safety doors but, I understand, there are no "fully approved" 35mm doors on the market. The story goes that there are many 35mm doors claiming to be fire retardant, but they don't meet the right standard (whatever that may be).

Does this make sense to anyone? What should the standard be? Is it only available in 45mm?

Many thanks.

[kurnal]

Hi Stretch
1- opening the doors to rooms will let the smoke detectoors operate more quickly BUT most important will allow the effects of fire and smoke to spill out of the room eliminating any chance you have of safe escape past the room on fire. Heres an illustration- nothing more - times are off the top of my head
Start a clock ticking.
Door open scenario- Fire starts at 0 secs. Smoke detector in room if fitted operates at 45 secs. Smoke fills ceiling space above door and spills into hall- 90 secs. Detector in hall operates 100 secs fire and smoke fill staircase and heat makes door impassable 200- 240 secs - result trapped upstairs after 4 minutes. Fire has free supply of oxygen escalates whole house well alight in 600 secs- still trapped upstairs- try to escape by window.

Door closed scenario- fire starts at 0 secs, smoke detector in room if fitted operates at 45 secs, room fills with smoke  100- 150 secs, wisps of smoke pass into hallway 120- 150 secs, smoke detector in hall operates 150-180 secs, door prevents spread of fire and most smoke into staircase, staircase with standard household doors remains tenable and cool for at least 600 secs, closed door inhibits supply of oxygen to fire, fire dies down.

Keeping the door closed means you know about the fire about a minute later - but it buys you at least 10 minutes extra time during which you can escape down stairs and limits the growth of the fire and subsequent damage.  


2- It may be possible to improve your existing doors- see products by www.envirograf.co.uk.