How do you fire upgrade a lath and plaster ceiling?

Underdraw the existing lath and plaster with chicken wire (supplied by others and fixed in accordance with manufacturer recommendations).

A cavity should then be formed by counter battening with minimum 38 x 38mm timber or by using GypCeiling Lining. Various Gyproc plasterboards can then be screw fixed to the underside of the battens depending on the fire performance required.