Sigma® OP4

Pre-insulated or open panel solutions


This wall type is ideal for very high performance designs, where air tightness less than 3, very low U-values, separate services cavity, air barrier and thinner wall build ups are desired.

This system utilises the existing 89mm or 140mm stud options and introduces separate rigid insulation overlay, dedicated service zone and conventional plasterboard, in combination with rigid polyurethane between the studs, as full or partial fill. U-values ranging from 0.22 – 0.12 can be achieved. Typically this would be specified for CSH Level 5, Section 7 gold rated, advanced FEES compliance or Passive Haus Homes.

Sigma® OP4 has the following benefits:

  • Separate air barrier membrane
  • Retains 89 or 140mm studs, for manual or crane erection
  • Limits wall thickness and maintains existing foundation
  • Reduces thermal bridging
  • Offers thinner wall to Sigma® OP3
  • Option to factory fit rigid insulation to achieve UKTFA Class B fire protection during construction


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