Fixed Tier Structures

SIS Global Seating can custom design, manufacture and install fixed tiered floors to suit any room size. Our experience over the years has allowed us to be involved in the design, development, manufacture and installation of a large number of installations around the country which includes a number of small to medium-sized product but also many very large, substantial and often complex tiering and platform projects.

Modular construction allows for ease of installation on site. This feature, when complemented with our in-house carpeting and seating installation, allows a room to be converted into a tiered lecture theatre, within a matter of a few days.

Converting a space into a tiered lecture theatre, auditorium or theatre improves the overall room appearance, increases capacity and improves sightlines and overall learning experience for all concerned. Fixed tiered structures can be manufactured to any riser and tread dimensions and can be constructed in a straight or curved configuration.


  • The structural design of the tiered floors conforms to the following regulatory and structural requirements: –
  • BS 6399: Part 1; 1996 “Loading for Buildings”/BS 449: “The use of structural steel in building”
  • Vertical deck loading satisfies the requirements of 4.0KN/m² uniformly distributed load, live loading as stated in BS6399.  Loading capacity 5.0KN/m² in the aisle positions.
  • Horizontal loading satisfies the requirement of 0.6KN/m² uniformly distributed load [15% of the vertical loading] as stated in BS 6399.
  • 40 x 40 x 3.2mm RHS section fully welded into supporting frames complete with base plates 125 x 125 x 6.0mm.
  • Supporting frames spaced at a maximum of 1200mm centres and linked laterally below deck level with 2N° sections of 40 x 40 x 4mm RHS. Support frames provided with diagonal bracing as required by structural calculations.
  • All treads and risers finished with 25mm thick plywood securely fixed to supporting framework with TEK screws applied in accordance with the manufacturer’s instructions.

Additional information

Fixed or Retractable?

Power Supply?


Require Tablet?


  • All SIS retractable units comply with BS EN 1090-1:2009 +A1:2011 & BS EN 1090-2:2018 – Execution of Steel Structures and Aluminium Structures.
  • SIS has CHAS Certification (Contractors Health and Safety Assessment Scheme) – SSISP (please see Accreditations).
  • SIS has Constructionline Certification – Gold Member – Construction Supply Chain Compliance – SSISP (please see Accreditations).
  • All SIS retractable units have their respective CE Marking Certification (please see Accreditations)
  • SIS Global Seating has been officially certified and operates an accredited ISO 9001 : 2015 Quality Management System (please see Accreditations).
  • SIS Global Seating has been officially certified and operates an accredited ISO 14001 : 2015 Environmental Management System (please see Accreditations)
  • These certifications mean that everything that SIS Global Seating design, manufacture and installs meets with these high exacting standards.

Retractable Structures

Find out more about our retractable structures.