CavityTherm is an innovative built-in insulation for traditional walls that achieves passive level U-values as low as 0.12 W/m²K with excellent thermal bridging detailing in cavities less than 150mm wide.

  • Engineered HIPs facer provides wind driven rain protection
  • Moisture redirected to outer surface
  • Prepositioned slots for sloping wall ties - no creep
  • Fully engineered jointing - no reliance on taping
  • Full range of accessory pieces build continuous system
  • Excellent Thermal bridging values
CavityTherm Typical U-values
(Inner Block 100)
Block Type 100mm 125mm 150mm
Light (0.15) 0.18 0.15 0.12
Med (0.33) 0.19 0.15 0.13
Dense (1.15) 0.20 0.16 0.13

Property & Units
Water Vapour Resistivity >100 (MNs/gm)
Thermal Conductivity 0.021 (W/mK)
Service Temperature -20 to +100 (ºC)

Dimensions & R-values
*PIR only
Length (mm) 1200
Width (mm) 450
Thickness (mm) 100 125 150
Typical R-value* 4.52 5.71 6.90



The built in wall insulation system shall be_ _ _mm CavityTherm manufactured  to BS EN 13165:2012 by Xtratherm, including corner boards and ancillary detail components comprising of CFC/HCFC free engineered jointed rigid Polyisocyanurate (PIR) with a lambda value of 0.021 W/mK with heavy low emissivity foil facings and engineered outer skin to achieve a U-value of_ _ _W/m²K wall element. Refer to NBS clause F30 155, F30 12. To be installed in accordance with instructions issued by Xtratherm.


CavityTherm provides a ‘system’ that delivers on U-values, is practical, and with a full range of innovative detailing accessories – it delivers on continuity.

Learn More
  • product-cavitytherm-accessory-1
    Integral Rain Barrier
  • product-cavitytherm-accessory-2
    Preformed Corner Panels
  • product-cavitytherm-accessory-3
    Service Void Panels
  • product-cavitytherm-accessory-4
    Jointing Strip
  • product-cavitytherm-accessory-5
    Hockey Stick Insulation
  • product-cavitytherm-accessory-6
    Cavity Tray Channel

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