A non-combustible glass wool cavity barrier used to restrict the spread of smoke and flames and to minimise flanking noise transmission in concealed cavities.

Isover ULTIMATE™ Cavity Barriers are multi-purpose insulation products providing fire, acoustic and thermal performance in concealed wall cavities. Isover ULTIMATE™ Cavity Barriers conform to building regulation definitions of a cavity barrier, cavity stop, flexible closer and effective edge sealing.


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Cavity Barrier
Cavity Barrier
Cavity BarrierCavity Barrier

Key Benefits

  • Excellent fire properties - Isover ULTIMATE™ Cavity Barriers provide up to 120 minutes fire protection in concealed cavities to help meet requirements of Approved Document B Fire Building Regulations (England & Wales) and Section 2 (Scotland).
  • Excellent Acoustic Properties - Cavity Barrier - Isover ULTIMATE™ Cavity Barriers minimise flanking sound transmission along the wall cavity to help meet requirements of Approved Document E Acoustic Building Regulations (England & Wales) and Section 5 (Scotland).
  • Provides effective edge sealing for party walls - Isover ULTIMATE™ Cavity Barriers reduce the thermal bypass effect by providing edge-sealing to the separating cavity wall at external wall and roof junctions.
  • Compact product range - Only 3 sizes needed to suit all cavity widths up to 100mm (50-65mm, 66-80mm and 81-100mm). Allows for simple, easy and cost effective storage.
  • Colour coded packaging - Avoids installation of the incorrect barrier sizes on-site. Allows for easier picking of the correct product in the warehouse.
  • Robust flexible material properties - Resilient to damage in storage, during transportation and on site during installation.
  • Storey height product - Reduces the thermal bypass effect by providing edge-sealing at the party wall/external wall junction. Fewer joints means less chance of installer error on site and a reduction in installation time.
  • Non-combustible  Isover glass mineral wool insulation has an A1 Euroclass fire rating – the best attainable.
  • Protected planet - Zero Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) of less than 5.

Variants Details

Product details

Order Code Width (mm) Length Cavity size Item type Product Name Sleeve colour
5200634281 100 1200 50-65 Barriers ULTIMATE Cavity Barrier - 30 minutes Yellow
5200634394 100 1200 66-80 Barriers ULTIMATE Cavity Barrier - 30 minutes Blue
5200634404 100 1200 81-100 Barriers ULTIMATE Cavity Barrier - 30 minutes White
5200634407 200 1200 66-80 Barriers ULTIMATE Cavity Barrier - 60 minutes Blue
5200634413 200 1200 50-65 Barriers ULTIMATE Cavity Barrier - 60 minutes Yellow
5200634419 200 1200 81-100 Barriers ULTIMATE Cavity Barrier - 60 minutes White
5200634420 300 1200 50-65 Barriers ULTIMATE Cavity Barrier - Party Wall Yellow
5200634421 300 1200 66-80 Barriers ULTIMATE Cavity Barrier - Party Wall Blue
5200634422 300 1200 81-100 Barriers ULTIMATE Cavity Barrier - Party Wall White
5200634423 300 2400 50-65 Barriers ULTIMATE Cavity Barrier - Storey Height Yellow
5200634424 300 2400 66-80 Barriers ULTIMATE Cavity Barrier - Storey Height Blue
5200634425 300 2400 81-100 Barriers ULTIMATE Cavity Barrier - Storey Height White