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Author Topic: Rooftop seating area  (Read 3124 times)
massive1969
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« on: March 25, 2018, 08:46:12 AM »

After some advice please...

A college is looking to use a rooftop space for a cafe seating area in the summer months.

The rooftop has a 1m high, brick built parapet wall around the complete perimeter of the roof space which is to be used.

The building was originally constructed in the 1800's. 

The total height of the building is approximately 20m (4 stories with high ceilings in each floor level).

There is only one means of escape being a protected internal stairway which discharges directly to fresh air at ground floor level.

We are asking a contractor to inspect the separation between top floor of building and roof top.

A new L2 system is being fitted throughout (we're looking at suitable sounders and visual alarms for the rooftop space too).

Is there anything else we really need to be looking at for this??  Any help / guidance would be much appreciated!
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nearlythere
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« Reply #1 on: March 25, 2018, 10:46:17 AM »

Just treat it like any other level. Being a PPA you obviously need to look at travel distances, occupancy factor, protection of escape route etc.
Building Control will have an interest.
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We're not Brazil we're Northern Ireland.
massive1969
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« Reply #2 on: March 25, 2018, 10:52:38 AM »

Brilliant - thank you Nearlythere.

Sorry - silly question...what is PPA?

I've just read that the parapet wall should be 1.1m - is this correct?
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Phoenix
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« Reply #3 on: March 25, 2018, 12:10:58 PM »

Yes, it should be 1.1m.

Technically, it shouldn't be allowed as the guidance only recommends up to 4 levels (including ground) if there is a single staircase and, I guess, this is a fifth level.  If I have read it wrong and this is the fourth level then that's ok.  Even if it is the fifth level it should be ok provided that the stairs are lobbied at all levels (but not at the rooftop).  As the top floor is over 18m the common alternative to lobbying of relying on a single fire door and the L2 alarm system will not really be adequate. 

Technically, with a floor over 18m you should have a firefighting shaft with firefighting lift!!  But you can argue that away by virtue of the fact that this is simply a seating area with a negligible fire loading and so there should never be a significant fire at rooftop level.

Similar argument for dispensing with the need for a fire door to the roof from the stairs - also this argument is supplemented by the fact that any heat and smoke will disperse upwards and not attack the door to the stairs.

Definitely less than 60 seats and maybe less depending upon the capacity of the staircase and the maximum populations on the other floors.  Travel distance no more than 18m to the storey exit. 

I guess the area might be inaccessible to people with impaired mobility but, if not, then you wil have to plan for their escape.

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massive1969
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« Reply #4 on: March 25, 2018, 01:07:42 PM »

Hi Phoenix, that's a great help - thank you. 

What guidance should we be looking at with regards to the 4 levels?
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Phoenix
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« Reply #5 on: March 27, 2018, 12:18:14 AM »

The proposal will be a material alteration and so Building Regs approval will be needed (possibly also planning?).  As such ADB will be appropriate guidance as opposed to the CLG guides for existing buildings.  There is no prescriptive guidance that allows four levels above ground on a single staircase when the top floor is over 18m, so you will have to make your own case.  Use the positive features of the design and use of the space to counter the deviations from the guidance.  
« Last Edit: March 27, 2018, 12:22:21 AM by Phoenix » Logged
lyledunn
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« Reply #6 on: March 31, 2018, 09:40:29 AM »

A recent project of ours provided a small beer garden to the rear of the third floor of a pub of similar age to your college building. The internal stairs provided the single MOE from the garden. The usual restriction of 60 persons was applied. The premises were packed to capacity when a kitchen fire set off the L2 alarm. Staff couldn't get people to evacuate, punters simply stood around and cheered! The fire must have developed quickly as the stairs became smoke logged, something which wasn't apparent to those in the beer garden. Eventually, some folk began to realise that there was indeed a danger and their movement precipitated the evacuation, albeit much delayed. The word on the street is that there were more than 150 in the beer garden alone!
All got out safely but it reinforces my long held contention that whilst L2 alarms and management systems are important control measures they should only be supplementary to the presence of an alternative way out.
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colin todd
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« Reply #7 on: April 01, 2018, 05:22:08 PM »

Well, try not to worry too much Tate and Lyle, very soon, if Dame Judy is to be listened to (but then why would she be) the skylines of the cities will soon be awash with New York-style fire escapes from all blocks of flats, along with the sprinklers and the smoke control (though there is already smoke control, so I assume this must be super duper smoke control), all because sparkies like you sometimes knock holes in things without fire stopping them.

After a night out at Shaftesbury Square, you will think you are seeing double down the Divis Tower there will be so many vertical lines.
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Colin Todd, C S Todd & Associates
massive1969
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« Reply #8 on: April 03, 2018, 04:51:09 PM »

Thank you all for your comments & guidance - much appreciated.
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