When Mgo board are attached to the wall, the wall takes on fire rating of the sheet.
A 10mm external sheet gives up to a 90 minute fire rating. A 12mm sheet gives a 120 minute fire rating and a 14mm sheet gives a 180 minute fire rating. There are a number of points to observe:
-The walls will require 14kg/m3 of fibre glass insulation at a minium of 70mm thick for 60 minute ratings, and 90mm thick for 90 minute and 120 minute ratings.
-Follow the fixing details described on the timber and stall wall installation brochures.
-Cladding of fire rated walls require particular at internal and external corners.
-Mgo board can be use of back blocking to all joints with the same thickness of Mgo wall board. By placing a 150mm width strip of Mgo board glued with an appropriate fire rated or structural polyurethane adhesive. To be applied in full length minimum 4mm beads to all stud and noggins then screwed into place to allow adhesion. This will help eliminate any thermal breaches and give additional protection to the frame.
-Place back blocks over the face of studs/beams/noggins by gluing and screwing in place prior to installation of the wall boards.
-Since all fibre batt insulation loses its effectiveness when wet, ensure drainage is provided to remove condensation from the cavity. It is good practice to install the cladding on battens so the air movement helps to prevent moisture build up.