Cavity Stop Sock

Cavity Stop Sock Cavity Stop Sock
Fire product

ARC Cavity Stop Socks

  • Up to 4 hours fire integrity
  • Horizontal and vertical options
  • Specified in terraced, semi-detached, apartments and major projects
  • Meets requirements of Robust Detail Part E and Approved Document B
  • Maximum cavity width available: 300mm
  • Easily installed with compression fit; no mechanical fix is required
  • Third-party certificated by IFC


ARC Cavity Stop Sock restricts the spread of smoke and flames within the cavity of external masonry walls. It is ideally suited for providing a cavity barrier within the external wall cavity, in line with a separating wall or floor as specified in Approved Document B, and for closing the cavity at eaves level.

Key stats

Length supplied 1.2m
Third-party certification Cavity Stop Sock: IFC certificate number: IFCC 1727 - Party Wall Cavity Stop Sock: IFC certificate number: IFCC 1728
Insulation Non-combustible rockfibre mineral wool
Thermal conductivity 0.037W/mK
Fire rating Up to 4 hours
Insulation performance Minimum 15 minutes
Test standard EN1366-4
Construction type Masonry
Orientation Vertical or horizontal
Robust detail performance E-WM 1-21

Frequently asked questions about this product

Can ARC Cavity Stop Sock be used around window and door openings?

ARC Cavity Stop Sock will provide fire and thermal properties when used around window and door openings. You will need to consider moisture penetration in your design as the product does not include an integral DPC.

Can this product be used with an SFS internal leaf?

ARC Cavity Stop Sock is fire rated and certified for use in a traditional masonry construction.

How do you install ARC Cavity Stop Socks?

Please follow the guidance on our datasheet and within our product video.

Do I take it out of the coloured sleeve?

The polythene sleeve is there to provide product identification and protection from the elements and should therefore be left in place. It does not add to the performance of the product so can be safely cut in to, and the product can still be used should the polythene be damaged.

Do you have to install a separate DPC or cavity tray?

The product does not include an integral DPC. A separate cavity tray or DPC should be installed where this is required by the location or type of building.

Can this cover multiple cavity sizes?

ARC Cavity Stop Socks are designed to suit specific cavity widths and are available in 5mm increments. It’s important that the appropriate size is fitted to achieve the required compression fit and to ensure the product performs as expected.

Industry awards and accreditations for this product

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