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It is necessary to install a lintel above the cavity that will be created to install the appliance. The hole which
must be created in the block wall should be 1220mm wide by 690mm high. The outer box requires only
1200mm x 670mm however an extra 10mm should be allowed around the perimeter to line the cavity with
non combusble board—this prevents heat from entering the cavity. The lintel required to support the recess
in the inner leaf (brickwork) should either be steel or reinforced precast concrete. The lintel should be the
depth of the inner brickwork and be at least 1500mm long. Mark the wall at the appropriate place, checking it
is horizontal and square. Mark the posion for the lintel centrally over this hole posion. Remove the
plasterboard and blockwork from this area and install the lintel using a suitable mortar. See diagram below.
Once the lintel is secure, proceed to remove the plaster, plasterboard and inner block work to the correct
dimensions.
The plasterboard should be removed in the area shown in the diagram below
PREPARING THE CAVITY WALL
