Excavations
Excavate the installation area to the depth of chamber plus 40mm, plus depth of base. Base of excavated area to be well compacted granular material or100mm concrete slab. Allow enough room around the chamber for a minimum concrete surround of 100mm. Concrete should be ST3 and of semi-dry workability.

Installation Guidelines
Install chamber centrally within excavation. Cut out duct ports as required and fit ducting into chamber. Ensure the ducting has a minimum 40mm key within the chamber. When the chamber is located correctly, backfill the void around the chamber with concrete as described above. Ensure backfilling is done around the perimeter of the chamber in equal measures on all sides to prevent movement or distortion. Fill to the height of the top lip of the chamber and concrete the frame in at the appropriate height/angle. It is strongly recommended that the frame is in-situ when installation of the chambers takes place.

Raising Pieces
Raising pieces obtain their strength from the chamber below and the galvanised steel frame inserted into the recess at the top. It is therefore imperative that both these items are in place for the duration of the installation. Only one raising piece can be used on each chamber.