Minimum Order Quantity: 5 items
Unilin (previously Xtratherm) CavityTherm is a continuous wall insulation system providing ultimate thermal performance with inbuilt protection from wind-driven rain.
The high-performance composite board of enhanced PIR has a lambda value of 0.021 W/mK, designed for full-fill cavity wall applications.
CavityTherm has gas-tight facings, with one face bonded to a profiled HIPS skin to provide a drainage plane.
The total coverage is 2.16m².
Key Features:
- Engineered HIPS facer provides wind-driven rain protection
- Moisture redirected to the outer surface
- Pre-positioned slots for sloping wall ties, preventing creep
- Fully engineered jointing
- Full range of accessory pieces for a continuous system
- Excellent thermal bridging values
- Continuous insulation layer
- Minimal cavity width requirement
- No engineer’s report required
- Ultimate U-values and compliance with standards
- See the Product Brochure and Installation Guide here
- See the Agrément Certificate here
- See the Specification Clause here
- See the Declaration of Performance here
For large quantities, call 0818 888 000 for a separate quote.
Thermal conductivity: 0.021 W/m²·K (BS EN 13165:2008) Typical R-value for 125mm version: 5.71.
Unilin (formerly Xtratherm) CavityTherm provides ultimate U-values in traditional wall constructions without needing an engineer's report, reducing heat loss.
It meets A+ or Passive standards with a 100mm cavity width, offering a continuous, easy-to-install insulation layer.
This system delivers an affordable, practical solution for high-performance wall insulation.
The engineered profiled facing directs moisture to the outer leaf for extra protection against wind-driven rain.
Boards feature rebated edges for tight interlocking, ensuring thermal bridging continuity.
Ancillary pieces insulate around services like hockey sticks, meter boxes, and corners.
Physical Characteristics:
- Density: 30 kg/m³
- Compressive Strength: >100 kPa @ 10%
- Thermal Conductivity: 0.021 W/mK
- Service Temperature: -20°C to +100°C
The profile allows wall ties to slope to the outer skin and acts as a mortar template.
CavityTherm has gas-tight facings, with one bonded to a drainage plane directing moisture to the outer leaf.
Its engineered profile maintains a residual channel, protecting the structure.
It helps achieve higher Code for Sustainable Homes levels, supporting the design of low-carbon homes with a 100mm cavity.
Note:
Delivery of this bulky product is available Nationwide but will be subject to a bulk delivery charge.
Delivery charges are calculated during checkout according to the delivery address provided.
For large volume orders, we may be able to offer a better delivery charge.
Call us on 0818 888 000 for more details and pricing.
Frequently Asked Questions:
What is CavityTherm?
A high-performance PIR insulation board with a moisture-draining bonded HIPS skin.
What are the benefits?
Achieves low U-values for energy-efficient designs, providing continuous insulation with added protection against wind-driven rain.
What wall ties should be used?
Standard S/S wire ties work well; low-conductivity ties are recommended for wider cavities.
Why slope the wall ties?
Sloping prevents water from travelling along the ties into the construction, ensuring moisture is directed outward.
What thicknesses are available?
Available in 100mm, 125mm, and 150mm, achieving U-values as low as 0.12 W/m²K.
What building types can use it?
Suitable for new external masonry cavity walls up to 25m high in domestic and non-domestic buildings.
What accessories are available?
A full range of accessories ensures airtightness, prevents thermal bridging, and maintains insulation continuity.
How do you detail insulation around trays/vents?
Bespoke pieces ensure continuity and prevent thermal bridging and condensation.
What is the Engineered Edge Detail?
Prevents a 0.01 U-value penalty by ensuring insulation continuity according to accredited detailing.
Jointing when cutting boards?
Use waterproof tape or preparatory self-adhesive strips for inside installation.
What is a Cavity Board?
Catches mortar drops during construction; easily cleaned with a damp cloth.
