You will most certainly have have to comply with a 1 hour fire rateing, which will mean two layeres of pink 12.5 mm plaster board if there is a living space above.
This is not an easy job, as each layer must be fixed securley and all gaps filled, then finale layer apply the same treatmeat as above then all joints taped and plastered over.
Because this is a commercial section, the spec gets upgraded to ensure safe escape of the peoples above in case a fire breaks out.
You may also need to inform your local building controll officer of the works you intend to do and they should be able to guide you better.
Joe Dybowski, July 2010
