Internal Planning of flats with more than one storey

[kurnal]

Please can anyone give me the benefit of their thoughts on para 2.16c on page 25 of ADB.
I am having a disagreement with a local authority building control officer on this topic.

In a  medium rise 7 storey  project, the 6 and 7th floors are 2 storey flats with access from level 6 only, the entrance door leads into a protected entrance hall, the bedrooms and bathroom are on level 6 with FD20S doors and the staircase rises to level 7 where the lounge and kitchen are  situated. The staircase is open at the top and we have specified interlinked smoke alarms in every room and a heat detector in the kitchens. I believe our design complies with para 2.16c.
The BCO disagrees and says that because the floors are higher than 7.5m above the ground level we cannot adopt this solution and must provide either exits from level 7, or sprinklers.

I contend that the rule was intended to ensure that if an individual flat had an internal vertical distance exceeding the 7.5m limit then something more than smoke alarms needed to be provided but for two and three storey flats full detection is ok without the provision of an alternative escape route.

Anyone have a view on this please?

[PhilB]

I agree with you Kurnal, alternative means of escape or sprinklers not required. When you say the stairway is open at the top do you mean the kitchen and lounge open directly into the stair or are theyprovided with fire doors?

I see no point in a door at the head of the stairs if doors are provided on the upper rooms.

[kurnal]

Hi Phil
Thanks for your reply.
The first floor comprises a lounge /diner   which is open to the head and side of the stair at first floor level- effectively a gallery. The small kitchen is an inner room off the lounge with a FD20 door sited remote from the staircase.  There is a smoke detector at the head of the staircase and a heat detector in the kitchen.

I made an assumption that in the event of a fire downstairs,(not withstanding the protected entrance hall) persons in the lounge would be at no greater risk if the head of the stair was left open, whilst if the TV catches fire in the lounge during the night, the full detection should ensure that persons sleeping downstairs will be aroused long before smoke logging affects the floor below the fire.

[PhilB]

I do see your logic but I can also see why the BCO says it doesn't comply with ADB. The stairway is not a protected stairway as defined in ADB.

If the lounge opens directly into the stairs it is the people sleeping below who may be at risk not the people in the lounge or kitchen.

Yes AFD may provide early warning before the stairs fill with smoke from the top down, and would in my opinion be a safe solution.

I can see your point that it is similar to a gallery but the requirements for galleries e.g visible area of 50% of floor below is designed to protect the people on the gallery, not those sleeping below it.

This is, in my opinion is where the guidance document does not provide all the answers. It will require a common sense approach that will leave the code huggers quaking in their bed-socks!!

Good luck old boy.

[wee brian]

Kurnal - yes the 7.5 m is measured internaly to the flat entrance, not ground level.

But as Phil says its not a protected stair if its open. Smoke will fill down the stair so enclosure at the top is necessary too.

You can sort your 7.5m argument by refering to the DCLG powerpoint that was used in the roashows when the ad was launched. http://www.bre.co.uk/filelibrary/presentations/Anthony_Brians_presentation.pdf
slide 37

[kurnal]

Many thanks to both for your advice.
The powerpoint answers the point perfectly and yes as you both point out the staircase is not a protected stair.

Thought about this for a while and do have a fall back of enclosing the stair at the bottom rather than the top.

But I was looking at it this way:

The worst case scenario for which my proposal may not be a safe solution is that someone is ill or blotto in bed downstairs and a smouldering fire occurs on the first floor causing total smokelogging of first the upper level and then as the cool smoke drifts downwards smoke in the entrance hall. But I cant see it being dense smoke in the lower level unless or burning materials from a fire upstairs fall down the open stairs, say Christmas decorations for example.

Whilst enclosing the staircase would give protection in these scenarios, the main entrance door to the flat is a maximum of 1.5m from the bedroom doors, and offset from the stair. The persons in the bedrooms on the lower level are probably at less risk than if the flat was all on one level and the same fire occurred in the lounge?

If we do enclose the staircase, and a fire occurs downstairs, the smoke and heat will be contained and concentrated within the escape route rather than rising to the first floor where there is a substantial smoke reservoir.
My view was that the increased risk to persons on the upper floor by enclosing the stair outweighed the increased risk to persons on the floor below by not doing.
But I cant give any empirical evidence to back this up- hence the fallback position if push comes to shove.

[wee brian]

You've lost me there mate.

The smoke will fill down from the top and the escape route becomes impassable.

enclose it on all floors - fire is contained in fire room and escape route kept clear.

[Big T]

The BCO obviously has the wrong end of the stick about the 7.5m rule. Fom what you have said he hasn't even questioned your protection of the staircase. (Bit of a worry)

The 7.5m rule is to cover flats that have more than 2 internal storeys.

If your flat does not exceed the 7.5m rule then 2.16 C is an acceptable solution (But i would review the stairway, i think it needs protecting in a traditional ADB sense).

If it does exceed 7.5 m then 2.16 A, B or D is the acceptable solution.

[kurnal]

Thanks to all for  the advice - much appreciated.