Masonry Cavity Stop Sock 552

Masonry Cavity Stop Sock 552

Masonry Cavity Stop Sock 552 has been designed to prevent passage of fire through concealed voids within the external fabric of a masonry wall construction.

The Stop Sock contributes in satisfying the requirements of guidance documents such as Approved Document B and The Scottish Technical Handbook.

Masonry Cavity Stop Sock 552 assists in reducing flanking sound transmission at wall and floor junctions and is suitable for both vertical and horizontal positioning to the edge of cavities, around penetrations and to sub-divide cavities.

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  • Manufactured from insulation slab bonded to fibre cement board, suitable for exposed and semi exposed applications
  • Designed for installation within masonry cavities
  • Accommodates a maximum void of 175mm
  • Tested and assessed to the basic principles of BS 476 Part 20: 1987
  • Suitable for both vertical and horizontal orientation
  • Solutions available offering either 60 minutes or 120 minutes fire resistance performance
  • Manufactured in bespoke sizes to suit the specified cavity width

Product Performance


Masonry Cavity Stop Sock 552 has been tested and assessed to the general principles of BS 476: Part 20 1987 by Exova Warringtonfire. The fire resistance performance is based on the barrier being installed between a suitable concrete / masonry structure.


  • Easy installation process
  • Installed under compression – The barrier is held in place under compression between the inner block work and outer masonry leaf
  • For voids up to 150mm a minimum compression of 15mm is required, thereafter 20mm compression is required up to the maximum void of 175mm
  • When installing Masonry Cavity Stop Sock 552 it may be necessary to consider additional use of DPC’s and/or cavity trays in relevant with Building Control guidance

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