Floor levels / mixed use buildings

[Meady]

Hi All,

Just looking for some clarification if possible please....

It is an existing building - 3 floor levels.  

Ground is commercial - 1st and 2nd floor levels are residential flats.

Using  guidance of LACoRS, do we use the examples of a 3-storey building or a 2-storey building as only two floors are residential??

Sorry - I know this is probably a really stupid question, but there is quite a difference in terms of what is required between 2 and 3 storey buildings.

Any help/guidance much appreciated.

[AnthonyB]

LACORS is notorious for overlooking this common situation. If the commercial unit is not adequately separated from the flats then you would end up following the 3 storey guides anyway as you'd need a Grade A mixed system covering both uses anyway.

The way the guide is phrased 3 stories is 3 stories but if the commercial is separate I can see the desire to take a sympathetic approach with a Grade D mixed system as the other fire precaution requirements are virtually identical if you don't use the escape windows option (which you wouldn't have at this height anyway).
 

Your choice at the end of the day - take the safe route and apply three stories guidance, or risk assess and justify the 2 storey approach (& be willing to defend it in case of any external scrutiny)