Minimum Order Quantity: 5 items
Unilin (formerly Xtratherm) CavityTherm is a continuous wall insulation system offering exceptional thermal performance and protection from wind-driven rain.
This high-performance composite board features enhanced PIR with a lambda value of 0.021 W/mK.
It is suitable for full-fill cavity wall applications.
It has gas-tight facings, with one face bonded to a profiled HIPS skin for a drainage plane.
Each pack covers 2.16m², with four 1200mm x 450mm boards per pack.
Key Features:
- Engineered HIPS facer for wind-driven rain protection
- Moisture redirected to the outer surface
- Pre-positioned slots for sloping wall ties—no creep
- Fully engineered jointing
- Full range of accessories for a continuous system
- Excellent thermal bridging values
- Continuous insulation layer
- Minimal cavity width requirement
- No need for an engineer's report
- 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 very large quantities, call us at 0818 888 000 for a separate quotation.
The typical R-Value for the 125mm version is 5.71.
Each board measures 1.2m x 450mm, with four boards per pack, providing 2.16m² coverage.
Unilin CavityTherm ensures excellent U-values in traditional wall constructions and minimises heat loss.
It meets A+ or Passive standards within a 100mm cavity width.
The system offers a continuous insulation layer at an affordable price.
CavityTherm’s engineered profiled facing redirects moisture to the outer leaf, protecting against wind-driven rain.
The rebated edge detailing ensures tight interlocking and superior thermal bridging performance.
Typical 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 profiled edge allows wall ties to slope down to the outer skin.
The bonded facer provides a drainage channel for structural protection.
It contributes to achieving low-carbon and Passive standard performance within standard cavity widths.
Note:
Delivery of this bulky product is available Nationwide but will be subject to a bulk delivery charge.
For large volumes, call 0818 888 000 for improved delivery pricing.
Frequently Asked Questions:
What is CavityTherm?
CavityTherm is a high-performance PIR insulation board with engineered facings for thermal efficiency and moisture control.
What are the benefits of using CavityTherm?
It meets Passive House performance levels while remaining practical and cost-effective for on-site construction.
What type of wall ties should be used?
Standard stainless steel wire ties may be used up to 5 per m².
Low-conductivity ties are recommended for wider cavities.
Why should wall ties be sloped to the outer face?
Sloping prevents moisture transfer across the cavity into the structure.
What thicknesses are available?
CavityTherm is available in 100mm, 125mm, and 150mm thicknesses.
What building types can use CavityTherm?
Suitable for domestic and commercial masonry cavity walls up to 25m high.
What accessories are available?
Accessories are designed to prevent thermal bridging at corners, meter boxes and service penetrations.
How should boards be taped if cut?
Use a waterproof tape or the available jointing strip to seal any cut edges.
What is a Cavity Board?
A cavity board prevents mortar from falling onto insulation during construction and can be easily cleaned and reused.
