App. doc B

[Hi Tower]

I wondered if somebody could assist me in the interpretation of paragragph 2.31 of App. doc B and thereafter 2.48 in relation to it with respect to a single access stair.

Para 2.31 state:  "Access to designs described in paragraph 2.48 may also be via a flat roof..............."

reference to Para 2.48 says "If a building is served by a single access stair...................."

My question is in respect to the above is does a single access stair mean the only stair available for escape as well?  if so; does it mean that a single external escape stair is acceptable when accessed from a flat roof where no other MOE is provided?

I hope my question isn't lost in interpretation

Many thanks in advance

[kurnal]

Yes I guess so HT. But in limited circumstances, limited to 6m high and the flat roof is protected and part of the same building. Why would they see a need to include this I wonder? Probably for access to flats above shops to make the flat self contained from the shop.

Oddly there is no equivalent reference in the old CP3 but there is much more reference to designs such as deck approach and staircases that are completely open at the base or the head. So it seems to be something  that crept in in the 1991 change from the old mandatory rules to the new ADB approach. I guess it reflects the times because in the 80s and 90s there was such a boom in subdividing larger buildings and houses into flats.

[Hi Tower]

Kurnal
You are right in this case - it is for access to flats above a shop.  Building Control suggested this was against the norm but when I indexed App. doc B I was pretty sure the above covered it.  Thank you very much for your reply
HT

[wee brian]

This was specifically put into ADB to allow flats over shops to be accessed by an external stair. The idea is that if the only way to get to your home is via an external stair then you will probably ensure that it is accessible. Where the external stair is only used for emergencies then it gets obstructed by tat/snow/parked cars etc.

[tmprojects]

Yes I guess so HT. But in limited circumstances, limited to 6m high and the flat roof is protected and part of the same building. Why would they see a need to include this I wonder? Probably for access to flats above shops to make the flat self contained from the shop.

Not a loaded question. but why limited to 6M? If the MofE is adequately protected what differentiates it from an enclosed staircase where 2.21 says a height of 11M in an enclosed MoE is sufficient?

[wee brian]

the 6m is about safety of external stairs and the impact of the weather. 

[tmprojects]

Thanks wb