Means Of Escape Using Accommodation Stairs in Retail

[Jon Barrett]

I hope you can help me on what might appear to be a basic question (I hope it turns out that way!).

It is common practice in two storey shop units to use an accommodation stairs towards the front of the upper level (leading to the lower level) to act as an alternative means of escape, together with a protected stairs at the rear of the unit. Although the accommodation stairs has to be discounted in terms of capacity.

Obviously the accommodation stairs, towards the front of the unit, offers no protection to fire and smoke. However, on the basis that it would only be used in the event of a fire towards the rear of the upper level, and occupants would be going down away from the smoke and be within a short distance of the front doors it is accepted as adequate.

My concern is that this arrangement is fine for able bodied people but not those who are wheel-chair bound for example.

Have I missed something here or is it is accepted that management procedures would intervene in this case to carry someone down the stairs?

Any corrections/comments on this would be much appreciated.

Thanks,

Jon

[kurnal]

Jon I assume the shop in question must have a passenger lift otherwise the wheelchair users could not access the first floor. In such a case the management must make adequate arrangements for their evacuaton in a fire which would normally involve provision of a refuge in the protected staircase and possibly an evacuation chair and staff trained on how to use it.

There are many rules and recommendations on the design of shops, and things can get quite confusing in the case of small shops. If you have access to BS5588 part 11 or building Regulations approved document B ( free download from DCLG website) you will see a number of scenarios.
 
At one extreme small 2 storey shops with no floor more than  280 sq m and not used as a restaurant or bar  may have a single, open stair only serving the first floor provided the stair is within 3m of an exit door from the ground floor.  Otherwise a single protected stair is allowed if the maximum travel distance is less than 18m from any point to the stair.

But outside the special exceptions made for small premises if it needs two staircases they should both be protected.  

I presume your accommodation stair is over and above the means of escape requirement and thus it does not figure in the evacuation plan of the building. There should be no need for procedures to use an accommodation stair in an emergency, especially not for disabled persons as the head of this stair is the most hazardous area of the building where persons will be at greatest risk from the effects of the fire- wherever it is.

[Jon Barrett]

Thanks for your prompt response.

Yes, there is a passenger lift to the upper level.

This shop has floors larger than 280m2.

With long narrow shops with 2 levels, now commonly found in shopping centres,  it seems common practice to possibly stretch the interpretation of BS5588:Part 11 Figure 7, Mezzanine levels.

You will see that Figure 7 a) allows the travel distance to the protected stair and the accommodation stair (inc. travel out at the lower level) to be the maximum single direction travel to each of the routes i.e. if the shop unit was long and narrow (rather than wide and shallow as in the BS) then you could move the protected stairs and accommodation stair to be around 24m (direct distance) apart. This would be OK for an able bodied person but could present a problem to a wheel-chair bound person if the fire was towards the rear of the unit.

I can't seem to find any other recommendations within the BS that would allow the use of the accommodation stairs in this scenario.

Any further comments would be appreciated.

[kurnal]

Sorry for going through the egg sucking routine in the first post.

I dont have an answer for you- I think you have hit on something here.

Is it a true mezzanine in accordance with the definition in 5588?
Is there a good view of the main floor?

I can see the merits in relaxations of travel distances / staircase protection for a true mezz and of course the unprotected stair in figure 7 is not actually an accommodation stair- it is part of the means of escape scheme and is an allowed, unprotected stair for MOE.

And taking it to its limit I guess diagram 7 and table 1 would allow the staircases to be almost 60m apart in the longest thinnest of mezzanines (less the distance to travel down the open stair to the final exit).

No clever answers either for the safe evacuation of wheelchair users in this situation. A refuge strategy is inappropriate for an open stair or mezz area, a well sited till positon next to the stair  with trained members of staff well versed in the use of evacuation chairs may be an answer - someone well versed in the use of the evacuation chair can sweep down a staircase almost merging with the flow of ambulant persons.

[wee brian]

This design is, as you say very common. It relies on the fact that people upstairs will be able to see the fire and react quickly.

Clearly with disabled people this approach is a bit of a problem, But the risk is still very low. I think staff training is a reasonable way of dealing with this.