AIM Horizontal Closer

Rockwool stone wool to polythene DPC Cavity Closer. The AIM Horizontal Closer has been designed to provide at least 2 hours’ resistance to the spread of fire past separating floors. It also significantly reduces flanking sound transmission within masonry wall cavities adjacent to separating floors. Rockwool red logo    

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  • Thermal Conductivity: λ = 0.034W/mK
  • Complies with Part E Building Regulations
  • Fire resistance performance of 2 hours’ insulation and integrity when installed with clips
  • Global warming potential = zero

Rockwool stone wool insulation

  • Length: 1200mm
  • Width: 260mm
  • Thickness: 50, 65, 75, 90, 100mm

DPC Polythene

  • Length: 1300mm
  • Width: 600mm
  • Overlaps: Top - 300mm, Bottom - 40mm, End - 100mm

The Rockwool insulation used for the Horizontal Closer, is precompressed to enable it to take up any minor irregularity in the wall void. This procedure also makes the insulation more flexible and easier to handle

Fire Performance

AIM Horizontal Closers provide a fire resistance performance of 2 hours’ insulation and integrity in terms of BS 476 Part 20. The mineral wool is non-combustible in accordance with BS 476 part 4 (1970). The DPC conforms to BS 6515 (1984). The Closer conforms with the 1994 Building Regulations and the National House Building Council Requirements.

The AIM Horizontal Closer will also provide at least 2 hours’ resistance to the spread of fire past the separating floor, when installed immediately above a row of metal wall ties or when installed with fixing clips.


The AIM Horizontal Closer has been designed to provide resistance to the passage of flanking sound within the wall cavity adjacent to separating floors and complies with the requirements of Part E of the Building Regulations.


The AIM Horizontal Closer should be installed in the external cavity wall at the level of the separating floor. The closer is installed with the wide DPC overlap uppermost, as indicated in the illustrations with the DPC embedded into the inner blockwork in the mortar layer above the closer, so as to form a cavity tray.

If being used as a fire closer, the product must be positioned immediately above a row of metal wall ties. If this is not possible the Horizontal Closer can be supplied with fixing clips. These are embedded into the mortar joint above floor level and the Horizontal Closer is impaled onto the clips.

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