CavityTherm Flex is the perfect solution when insulating fair faced inner block walls or when block is laid flat resulting in an uneven surface to accept the insulation. The 25mm fibre layer absorbs any variations due to block tolerances, providing a continuous unbroken bond between insulation layer and block. CavityTherm Flex 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
  • Flexible backing to eliminate indentations
  • Prepositioned slots for sloping wall ties
  • Fully engineered jointing
  • Full range of accessory pieces build continuous system
  • Excellent Thermal bridging values
CavityTherm Flex U-values
(Inner block 215)
Includes 5mm residual cavity, 15mm fibre, plaster finish.
Block Type 120mm 150mm
Light 0.15 0.14 0.12
Med 0.33 0.16 0.13
Dense 1.15 0.17 0.14

CavityTherm Flex U-values
(Inner block 100)
Includes 5mm residual cavity, 15mm fibre, plaster finish.
Block Type 120mm 150mm
Light 0.15 0.16 0.13
Med 0.33 0.17 0.14
Dense 1.15 0.17 0.14

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

CavityTherm Flex
Dimensions & R-values
* PIR and Fibre
Length (mm) 1200
Width (mm) 450
Thickness (mm) 120 150
Typical R-value* 5.19 6.62



The built in wall insulation system shall be
___mm CavityTherm Flex 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) – fibre composite, with a lamba value of 0.021 W/mK with heavy low emissivity foil facings and engineered outer skin to achieve a U-value of___W/m²K for the wall element. Refer to NBS clause F30 155, F30 12. To be installed in accordance with instructions issued by Xtratherm Ltd as part of the Xi Platinum Service validation process.


Do you have any questions?

Tale to the team who can help you with your project

Our Technical Team provides technical services throughout our customer bases in Ireland & UK. Their experience and expertise has been built through our engagement and participation with the Irish construction industry for over 30 years.

Certified Technical Knowledge.

Solutions you can trust.

Call The Technical Team:
Tel +44 (0) 371 222 1055
Tel +353 (0) 46 906 6050

BBA Cert Logo


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

Callback Request

Fill in your details below and we will contact you!