Minimum Order Quantity: 5 items
Unilin (previously Xtratherm) CavityTherm is a continuous wall insulation system delivering exceptional thermal performance with built-in wind-driven rain protection.
It is a high-performance PIR composite board with a lambda value of 0.021 W/mK, designed for full-fill cavity wall applications.
The gas-tight facings and profiled HIPS skin create a drainage plane to manage moisture.
Key Features
- Engineered HIPS facer for rain protection
- Redirects moisture to the outer surface
- Prepositioned slots for sloping wall ties—no creep
- Fully engineered jointing for a tight fit
- Full accessory range for a continuous system
- Excellent thermal bridging values
- Continuous insulation layer
- Minimal cavity width requirement
- No engineer's report needed
- Achieves ultimate U-values & meets standards
Thermal Performance
- Thermal Conductivity: 0.021 W/mK (BS EN 13165:2008)
- Typical R-Value (125mm): 5.71
- Total Coverage: 2.16m²
Advanced Moisture Protection
CavityTherm’s engineered profiled facing ensures any moisture penetrating the external wall is redirected back onto the outer leaf.
The rebated edge detailing on all four edges interlocks tightly, ensuring excellent thermal bridging detailing and system continuity.
Typical Physical Characteristics
- Density: 30 kg/m³
- Compressive Strength: >100 kPa @ 10%
- Service Temperature: -20°C to +100°C
Smart Design for Easy Installation
The profiled edge allows wall ties to slope down to the outer skin, acting as a template for mortar on the inner skin.
The gas-tight facings and drainage plane provide additional moisture protection.
Energy Efficiency & Sustainability
CavityTherm achieves U-values aligned with Code for Sustainable Homes targets, enabling architects to design low-carbon homes while maintaining a 100mm cavity width.
It meets A+ and Passive standards, making it a practical and cost-effective choice for energy-efficient wall insulation.
More Information
- See the Product Brochure and Installation Guide here
- See the Agrément Certificate here
- See the Specification Clause here
- See the Declaration of Performance here
Note:
Delivery of this bulky product is available Nationwide but will be subject to a bulk delivery charge.
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 offer better delivery rates—call 0818 888 000 to discuss pricing.
Frequently asked questions:
What is CavityTherm?
CavityTherm is a high-performance PIR insulation board (λ = 0.021 W/mK) with gas-tight facings.
One side features a profiled HIPS skin to channel moisture away.
Rebated edges ensure a secure fit.
What are the benefits of using CavityTherm?
CavityTherm achieves Passive House U-values in a 150mm cavity, ensuring thermal continuity for a cost-effective, low-energy build.
What wall ties should I use with CavityTherm?
Standard stainless steel wire wall ties (up to 5 ties/m²) are suitable.
Low conductivity ties may be needed for wider cavities, but they can increase thermal bridging at junctions.
Why should wall ties slope downward?
All wall ties, regardless of insulation type, should slope slightly downward to prevent water from tracking into the structure.
What thicknesses are available?
CavityTherm comes in 100mm, 125mm, and 150mm, achieving U-values as low as 0.12 W/m²K.
What types of buildings can use CavityTherm?
It is suitable for masonry cavity walls in domestic and non-domestic buildings up to 25m high.
What accessories are available?
Xtratherm provides bespoke insulated pieces to prevent thermal bridging around vents, cavity trays, corners, and meter boxes.
Why does CavityTherm have engineered edge detailing?
It ensures continuous insulation, avoids gaps, and prevents the 0.01 U-value penalty required by BR443 calculations.
How do I seal cut boards?
- Remove profiled edges, butt boards tightly, and seal.
- Inner leaf first? Use waterproof tape on dry surfaces.
- Building from inside? Apply self-adhesive jointing strip.
- Services through insulation? Slope them outward and dress DPCs over services per Eurocode 6.
What is a cavity board, and why use it?
A cavity board catches mortar drops during construction, preventing buildup.
HIPS skin on CavityTherm is easily cleaned with a damp cloth.
