Cavity Wall Insulation: Cavity Closers

Cavity wall insulation is a key part of the UK's Part L Building Regulations which require all specific junctions to be addressed in terms of cold bridging and thermal envelope continuity. The scope of the regulations covers all thermal insulation products. 

Another important consideration is the ability of insulation products to prevent the spread of fire, especially in brick and block, steel, timber-framed, attached, or multi-occupancy buildings.

Cavity Wall-Opening Insulation

For window openings and doorways, the right size cavity closer is an essential part of the Part L insulation strategy for any new building, retrofit project, or extension. The Eurocell Cavalock and YBS Easiclose cavity closers are straightforward, and fast to install.

• Whatever the specified size of the cavity, these closers can be adjusted to fit all standard cavity widths, from 50mm to 150mm. 
• The polystyrene insulation is marked with pre-cut grooves to help cut to the exact size required with a minimum of waste or mess.
• The rigid plastic can be cut easily with a hand, or a circular saw. Fix your cavity closers directly to the window frames when the windows are built into a wall.
• Cavalok uses post-market uPVC to manufacture their cavity closers, which means that the raw material used is recycled replacement windows.

Cavity Fire-Stop Insulation

Cavity stop closers are filled with rockwool insulation and are primarily designed to impede the spread of fire in a cavity. In addition, these cavity stop closers will also contribute toward sound insulation and stopping heat transfer.

Firezero closers, or socks, are made with rockwool slabs, which literally cannot burn as it is made from mineral fibre. It will melt at 1000°C, but before this happens, a fire in an urban setting would likely be under control by the fire service.

The official rating is for 30-minute protection, the time required for full evacuation under BS476: part 4: (1984). However, the Firezero Multisock cavity stop closer system has been independently tested to deliver over an hour resistance to fire.

Colour, Size and Location

The colour-coded printed sleeves make them easy to identify. The text includes the regulations, certification, and fire rating.

The Firezero products come in three sizes, 100mm, 125mm, and 150mm to cater to every dimension of wall cavity. They are ideal for use with rockwool cavity slabs as they have the same internal structure, resistance to moisture, mould growth, sound transference, and heat.

Fit them within the cavity between semi-detached properties, at the top of a gable party wall between dwellings, and between floor levels of multiple-occupation buildings. Always make sure that they are fitted continuously, without breaks, to properly compartmentalise the building structure.

Get in touch with our pro team today to confirm your insulation specifications.