No Products in the Cart
When selecting insulation boards for your project, it’s important to choose the right product for your specific application. Within the Celotex range, three of the most popular options are the TB4000, GA4000, and XR4000 boards. While they all share the same high-performance PIR (polyisocyanurate) core, each has unique properties that make it best suited for particular uses — whether that’s insulating walls, roofs, or floors.
This guide breaks down the differences between Celotex TB4000, GA4000 and XR4000 boards, explaining their main features, typical thicknesses, and where each product performs best.
The Celotex 4000 range is made up of rigid PIR insulation boards designed for exceptional thermal efficiency across a wide range of building applications. All three products — TB4000, GA4000, and XR4000 — share the same basic composition: a lightweight, high-performance foam core bonded to low-emissivity foil facings on both sides. This construction helps to minimise heat loss and improve U-values across your building envelope.
Each product in the 4000 series is designed for a different insulation depth, ensuring you can choose the ideal board for your space and building requirements. Whether you need to fit insulation between rafters, under floors, or within wall cavities, there’s a Celotex board tailored for the job.
The Celotex TB4000 range is the thinnest in the 4000 family, making it ideal for tackling thermal bridging in tight or difficult-to-insulate areas. Thermal bridges occur where heat escapes through elements such as wall ties, joists, or steel beams — places where full-thickness insulation cannot be installed.
Because it’s so thin, TB4000 is perfect for retrofit or renovation projects where space is limited. It helps maintain consistent insulation across the building fabric, reducing cold spots and improving overall efficiency.
The Celotex GA4000 board is the most versatile product in the range and is often described as the “general application” board. It’s suitable for a wide variety of domestic and commercial insulation projects, providing an excellent balance between performance, affordability, and ease of installation.
GA4000 is the go-to option for most projects, offering reliable performance and flexibility. It’s easy to cut, lightweight to handle, and compatible with standard building details. Whether you’re insulating a loft conversion or improving the thermal envelope of a home, GA4000 provides dependable results.
The Celotex XR4000 series is designed for projects requiring thicker insulation layers to meet stricter U-value targets. It shares the same core and performance characteristics as GA4000 but is available in significantly greater thicknesses, making it suitable for high-spec applications.
If you’re looking to achieve low-energy building standards or projects close to Passivhaus, XR4000 is the preferred choice. Its thicker profile minimises heat loss through building elements while keeping the overall structure lightweight and manageable.
All three Celotex boards deliver premium thermal performance and are certified for reliability and efficiency. The main difference lies in their thickness and intended application:
When combining insulation boards, TB4000 can be paired with GA4000 or XR4000 to provide continuity at junctions, ensuring a seamless thermal barrier throughout your project.
At Cut Price Insulation, we stock the full Celotex 4000 PIR Range, including TB4000, GA4000, and XR4000 in various thicknesses. Whether you’re an installer, contractor or homeowner, we can supply boards individually or in bulk to meet your budget and project requirements.
Also, if you’re exploring alternatives or broader options beyond Celotex, be sure to check out our post on Alternatives to Celotex & Other PIR Insulation Options for comparison insights and material recommendations.
The Celotex 4000 range offers a solution for every insulation challenge. TB4000 is designed for thin applications and preventing thermal bridging, GA4000 serves as the general-purpose all-rounder for walls, floors, and roofs, while XR4000 delivers the extra thickness needed for maximum energy efficiency.
Whatever you choose, all three Celotex boards provide outstanding thermal performance, durability, and value for money — helping you create a warmer, more efficient building.
