Distance/fire separation between lower and upper floor external windows?

[Tom Sutton]

I received this query the other day and cannot find a satisfactory answer.

Is there a specific distance/fire separation between lower and upper floor external windows? This is in regards to a fire breaking out of a flat window on a lower floor licking" up into window of flat above?

[Tom Sutton]

I am coming to the opinion that there cannot be a solution to this, it is a natural phenomenon and other that making external wall fire resistant with no openings, which would be ridiculous, there is no answer.

Any other opinions?

[kurnal]

I think there are papers on this - fire plumes and adherence to walls, but can't remember where - SFPE manual or CIBSE E perhaps? Of course in flats the floor is a compartment floor so an external breach is potentially  serious, cladding and firestopping, rain screen cladding and external fire spread are as you know covered in ADB but I think  fire spread between floors was pretty rare until Lackenal House

[Fishy]

I received this query the other day and cannot find a satisfactory answer.

Is there a specific distance/fire separation between lower and upper floor external windows? This is in regards to a fire breaking out of a flat window on a lower floor licking" up into window of flat above?

Can't be a minimum distance, otherwise Juliet balconies would be verboten?

[John Webb]

Most of the studies on fire transmission through windows seem to concentrate on the likelihood of spread of fire to or from other buildings. Howard Morgan* and others looked at smoke and flame transmission up walls, mostly in connection with the work on fire venting in shopping centres and other atrium buildings. (eg BR 258). Cladding of buildings does have limits set in AD 'B' not only for resistance to external fires but to limit spread as well (Section 12).

(*I'm sorry to report that Howard died early in September after 8 years of suffering from Parkinson's; funeral was held on Thursday 24th Sept.)

[colin todd]

Johnnie,  I was very sad to hear of Howard's death.  Can you possibly email me contact details for Penny, as I would like to send condolences.

[John Webb]

Johnnie,  I was very sad to hear of Howard's death.  Can you possibly email me contact details for Penny, as I would like to send condolences.

Colin - PM sent to you.

[Tom Sutton]

All I could find was, ADB does deal with fire resistance of external walls but only to preventing fire from/to adjacent buildings, not this problem.

The only research I could find is into how a fire plume behaves as it passes through an opening to outside, small opening, plume projects away from the building, large opening, plume rises and keeps to wall but I didn?t need complicate maths/CFD to tell me that.

I think wind effects on a building is important when winds act upon a building the air pressure will increase on the windward side (positive pressure) and reduce on the leeside (negative pressure) and if there are openings between the two sides, air will be drawn into the positive side and discharged to the negative side. If the fire is on the windward side, this could mean if windows are open, the plume could be drawn into the building spreading the fire; also the wind would blow the plume towards the face of the building.

This is a natural phenomenon and I cannot see how it can be prevented, the only solution, is insuring the external walls are fire resistant and all windows are kept shut which isn?t very practical but it could be done to a limited level.  Think it is something we will have to live with for some time; at least until DCLG decide to review ADB. Thanks Guys.

[Phoenix]

This is something that has been ignored for too long.  Some of you will be aware of what happened at the Monica Wills fire in Bristol a few years ago.  The fire spread externally from a ground floor car park to the flats above.  At the Almondbury School fire, rather longer ago, the fire spread from the ground floor to the first floor by an external route.  There are, of course, other examples of fire moving from one floor to another via an external route.

In Gibraltar, where a compartment floor meets an external wall, they have a solution that makes part of the external wall fire resisting (in a band around the building covering the junction between floors) or, if there is a balcony, the compartment floor is continued outside to include the balcony floor which directs products of combustion away from the face of the building.  I think this is a very good idea.

[Tom Sutton]

I fully agree Phonix. A more recent fire, Lakanal House was where the fire spread externally and the coroner has asked the government to look at ADB but it's anybody's guess how long we will have to wait for that.

The research I looked at on fire plumes exiting through openings also looked at the floor being extended past the face of the external wall, about a 1 m, which could be a balcony. I also found a paper on a fire in a multi storey block in Hong Kong where the fire had spread externally and their solution was sprinklers. I think the research is there it just needs somebody to act upon it.

[colin todd]

Tam, in the greater scheme of things, it is not worth owrrying about.

[wee brian]

The UK approach is explained in BRE - BR 135.

Where there's been any research on this issue it tends to show that the requirements for FR balconies and spandrels don't work. so iether ban windows on alternate floors or decide to accept the risk.

[colin todd]

or introduce a window tax to discourage the use of windows.  Who on earth would want to look out of their window and see London, Manchester or Liverpool anyway?

[Mike Buckley]

Not to mention the savings in energy just think of all that heat disappearing out of those windows!

[kurnal]

Time windows were taxed. You know its for your own good.