Fire Exit to adjoining unit

[guynouk]

Hi. Just like to say thanks to Kurnal for allowing me to Register. Have spent a good few hours reading through some of the Forum posts. The questions and responses/comments are excellent. There are some similar questions to mine but nothing exact so if it's OK I'd like to describe my issue and ask a question.

I've taken a lease on a unit (Unit 1) that needs extensive refurbishment with a view to converting it into a bar. It's on 2 floors. A large basement and a slightly raised (about 1m from street level) Mezzanine Floor that extends over 75% of the Basement area. There is one main staircase down to the basement. In the basement there is an exit in an adjoining wall to next doors equally sized unit (Unit 2. Albeit some of it is taken up by an apartment block lobby - slightly confusing so please see very rough sketch attached). Both Units have the same landlord. Travel distance to this exit in the basement is approx 18m. Is this exit acceptable as a fire escape route with final exit being through the other units front exit/entrance?

All I can get out of the fire department (who i called for advice) and the Bldg Inspector who recently popped in as he was walking past at the time (apparently we're in his in tray) is "we don't really like that solution". That doesn't really confirm anything.

All other solutions are extremely expensive and involve building fire escape staircases in next doors unit, breaking thru their Mezz Floor and breaking into the apartment block lobby (same landlord). There is only one external wall. All the rest are party walls so other alternatives are limited.

We're about to press on with work ie laying the screed floor and am keen to avoid rework if the solution we're proposing is unacceptable and has no chance of approval.

As the landlord owns both units he could quite easily write this shared fire exit into both leases. I've already spoken to the other party who are in the final stages of negotiating the lease on the other unit. They're fine with this shared exit solution. Opening hours will be approx the same for both units.

Have you guys got any experience on this that you can pass on?

Thanks in advance for any replies.

[kurnal]

What size is your unit, how wide is the exit and the staircase? How high is the building, how many apartments per floor?

[guynouk]

Hi Kurnal, many thanks for the reply.
The unit floor area is approx 8m x 20m (160m2) for the basement and slightly less on the Mezzanine Floor.
The size of the exit between the 2 units is 1050mm.
The main staircase from the Mezz Floor to basement will be a minimum of 1050mm (yet to be installed).
The front exit is greater than 1050mm. All doors opening outwards.

With respect to the apartment block.
There's no interaction between the 2 x units and apartment block unless of course we are forced to break thru into the Apartment Block Lobby/Lift area to fit another exit. In which case there are 8 floors. Approx 30 metres high. 5 apartments per floor.

Thanks

[kurnal]

I will kick things off for you with my initial thoughts without deep consideration  and hope to prompt further discussion.
Basement fires are nasty things - the lower the ceiling the nastier and the faster conditions deteriorate. Then the convective forces mean that unless enclosed at the base persons have to pass through the heat layer to escape and fire fighters descend through this heat layer, often impossible. At least you have a mezzanine implying a high ceiling over most of the floor and if the escape was into the adjoining unit then this would be an advantage keeping people on the level without rising through the heat layer. But controls would need to be in place to ensure sufficient space in the adjoining unit to ensure persons may safely disperse into it to prevent queuing in the club. Whereas if the route passed via the flats lobby one hours separation should be maintained between the purpose groups.

It would be appropriate as a minimum calculate travel distances and to  size exits based on high risk, purely as a rule of thumb ADB would suggest 2 minutes evacuation, the exit sizes in ADB are based on 2.5 minutes so exits should be at least  20% bigger than the tables in ADB suggest, unless modelling is carried out to prove otherwise.

Consideration needs to be taken of access for firefighters in addition to means of escape.

Licenced premises are a particular problem when it comes to time to respond, and co-ordinate an evacuation.

Have you seen the video on the station nightclub fire?  

[guynouk]

Thanks Kurnal. I'd not seen the video until now. I can see what you mean about Basement fires!!
Although we're not a night club. More a bar/food type place.
And yes ..... as you said there's a high ceiling over some of the basement .... I'd say 25% of it, as there's an open aspect at the front.
Next doors unit is of equal size. Intended use is as a restaurant so numbers will be limited to the available tables/chairs they have.
There is the potential to put another door thru into next doors unit (in the middle of the adjoining basement wall under the Apartment block lobby) so opening up another exit.

Yes, hopefully others can contribute to the discussion. Thanks.

[Owain]

Bar/food = kitchens = increased fire risk compared to a bar.

Restaurants can vary a lot in terms of 'covers' per sq metre.

For fine dining, you should allow 18 to 20 square feet per customer. Full-service restaurants typically have about one seat per 12 to 15 square feet, while fast-food operations reduce this figure to as little as 11 square feet.

(American site, convert to sq metre).

Fast food will allow space for diners to eat quickly and leave. Seating is often fixed, and lighting is bright. A banqueting type restaurant may have a much tighter arrangement (one site suggests 10 sq ft per person) as once diners are sat they will tend to stay sat, and it doesn't matter if it takes 10-15 minutes for everyone to squeeze out -- except in a fire of course.

Then you have the nights the restaurant folds away all the tables and has a standing buffet for 3 x 'normal' capacity with the chocolate fountain or vodka luge set up blocking the exit.

[AnthonyB]

The BCO doesn't like it as using adjoining premises/other occupiers as it's a bit of a 60's throwback and Approved Document B doesn't normally allow it (Para 3.16).

Can Unit 2's exit's combine the capacities of both units at once?
Are you linking alarms for full evac?
How can you be sure the route won't be obstructed?
How do you get out of Unit 2 if it's closed - you've no guarantee they will always be open same hours, same days?

Also escape through Residential from different Purpose Groups is frowned upon, but at least there are options for this (lobby protection) in certain circumstances.

You would normally be expected to have your own final exits or a shared protected route that's not part of the occupied space these days - you would be advised to seek the advice of a fire engineer as I can't see how you'd meet Building Regulation requirements without an engineered solution as benchmark guidance wouldn't allow your suggestions for new builds/refurbs/conversions

[lyledunn]

I know things are a tad different in England but here in NI you would be lucky to get BC approval for your project. Even if you did, the entertainment licence would restrict you to 60, hardly enough to claw back your outlay! I'm just about to post on a similar issue.