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ROCKWOOL SP Firestop OSCB 60 and 120

Specifically designed for use only in conjunction with ROCKWOOL RAINSCREEN DUO SLAB, SP Firestop OSCB forms an open-state cavity barrier within the building facade, which allows for ventilation and drainage of the cavity under normal service conditions.

SP Firestop OSCB is available in two variants giving 60 and 120 minutes' fire performance respectively: SP Firestop OSCB 60 and 120. Each comprises of a continuous intumescent strip fixed to the leading edge of a foil faced stone wool barrier, encapsulated by a weather-resistant polythene sleeve – coloured white for OSCB 60 and red for OSCB 120.

Fully tested to ASFP TGD 19, the combination of non-combustible insulation with an effective intumescent supports the construction of safe facade systems and aids the design of high-rise buildings over 18 m in height. Installed horizontally and designed to ensure an appropriate open air space is maintained, the SP Firestop OSCB is suitable for overall cavity widths up to 425 mm.


  • Up to 120 minutes' fire integrity and insulation.
  • Satisfies NHBC and CWCT guidance for ventilation gaps at fire barrier locations.
  • Weather resistant.
  • Combined with Rockwool Rainscreen Duo-slab, it simplifies the design of high rise buildings above 18 m.

General information

Uniclass 2015

Pr_25_80_80_42 Intumescent coated foil mesh flexible cavity barriersPrimary


F30/18 Cavity closers

F30/180 Cavity closers

K10/530 Cavity fire barriers within partitions/ wall linings

P10/420 Sleeved mineral wool small cavity barriers

P10/70 Sleeved small cavity barriers

P10/75 Wired small cavity barriers

Specification data - Intumescent coated foil mesh flexible cavity barriers

Product Reference



Overall cavity width

See 'Options below and insert requirement.



OSCB fixing brackets

Maximum 500 mm centres.

Pig tail screws

For ROCKWOOL SP Firestop OSCB 60 only. Maximum 333 mm centres.

Standard product features


90 mm.


1000 mm.

Product Options

Overall cavity width:

Available in range of sizes up to the maximum stated. Consult manufacturer's literature for details.

  • ROCKWOOL SP Firestop OSCB 60 maximum cavity width: 425 mm (maximum product width: 400 mm; maximum open cavity with: 25 mm).
  • ROCKWOOL SP Firestop OSCB 120 maximum cavity width: 300 mm (maximum product width: 256 mm; maximum open cavity with: 44 mm).

Fire rating:

  • ROCKWOOL SP Firestop OSCB 60: EI 60.
  • ROCKWOOL SP Firestop OSCB 120: EI 120.

Standards and approvals:

Fully tested to ASFP TGD 19: “Fire Resistance Test for ‘Open-State’ Cavity Barriers used in the external envelope or fabric of buildings”.

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