UKFR - ROOFING AND INSULATION SPECIALISTS

Celotex vs Kingspan - Which is better?

Celotex and Kingspan are two of the biggest insulation brands out there - but which one is superior? The answer to this question depends on a few factors including cost and performance. Generally speaking, Celotex is more cost effective, with a range of standard boards suitable for broad applications. On the other hand, Kingspan is more expensive but has a larger range of specialist products, each designed with a specific application in mind. In this guide, we’ll break down everything you need to know about Celotex and Kingspan, so you can make an informed decision.

Brief Overview

We know not everyone has the time to read through an in-depth guide, so here is a quick side-by-side comparison of the two.

Celotex	Kingspan
✅ More affordable	❌ Generally more expensive
✅ Good thermal performance	✅ Superior thermal efficiency
✅ Suitable for general use	✅ More durable and rigid
❌ Limited resistance	✅ Highly moisture-resistant
❌ Not suitable for warm deck flat roofs*	✅ Suitable for warm deck flat roofs
✅ PIR insulation	✅ PIR & Phenolic insulation
✅ Easy to install	✅ Easy to install

Shop Celotex Insulation →Shop Kingspan Insulation →

Which board is right for my project?

Insulated Plasterboards – PL4000 as PIR VS K118 as Phenolic

There are two main options for insulated plasterboard – Celotex PL4000, which is made from PIR, and Kingspan K118, which is made from Phenolic.

Criteria	Celotex PL4000 (PIR)	Kingspan Kooltherm K118 (Phenolic)
Thermal Performance	0.022 W/mK	0.019 W/mK
Material Composition	PIR	Phenolic rigid foam
Moisture Resistance	Good	Excellent
Durability	Rigid and durable	Rigid and durable
Fire Ratings	Good fire resistance which achieves Euroclass B-s1, d0	Good fire resistance which achieves Euroclass B-s1, d0
Environmental impact	Contains thermoset plastics, limited recyclability	Similar environmental profile, but higher efficiency may reduce energy use
Costs	Lower initial cost	Higher initial cost but better thermal performance

Shop Celotex PL4000 →Shop Kingspan K118 →

What is the best insulated plasterboard?

If you want the best insulation possible, Kingspan Kooltherm K118 is the right option due to its phenolic composition offering a better thermal and moisture-resisting performance.

If you’re working with a small budget, Celotex PL4000 is the best choice for you. Whilst K118 does offer high performance, PL4000 is more than suitable for most plasterboard applications.

Cavity Boards – Thermaclass 21 vs K106 vs K108

When it comes to insulating cavity walls, there are a few different choices; Celotex Thermaclass 21 which is made from PIR, and Kooltherm K106 and Kooltherm K108, which are both phenolic.

Criteria	Thermaclass 21 (PIR)	Kooltherm K106 (Phenolic)	Kooltherm K108 (Phenolic)
Thermal Conductivity (λ-value)	0.021 W/m·K	0.019 W/m·K	0.019 W/m·K
Material Composition	Rigid PIR with low emissivity foil facings	Rigid phenolic with water-tight fleece outer facing	Rigid phenolic with low emissivity foil facings
Moisture Resistance	Tongue and groove edges help resist wind-driven rain	Enhanced moisture resistance due to water-tight fleece	Moderate moisture resistance with foil facings
Durability	Long-lasting rigid foam	Long-lasting rigid foam	Long-lasting rigid foam
Installation	Lightweight boards with tongue & groove edges for easy fitting	Compact boards designed for full-fill cavity walls (10mm residual cavity)	Compact boards designed for partial-fill cavity walls
Cost	More budget-friendly	More expensive	More expensive

Shop Thermaclass 21 →Shop Kooltherm K106 →Shop Kingspan K108 →

What is the best for cavity walls?

Thermaclass 21 is the best choice for cost-effective performance, offering a good balance between affordability and thermal efficiency.

K106 is the best choice if you require maximum thermal performance and moisture resistance, as it comes with a water-resistant outer layer.

K108 is the same as K106, but without the water-resistant layer, which is ideal if you have limited cavity space or are installing where moisture isn’t a concern.

Multipurpose Insulation – Kingspan TP10/TW55/TF70 VS Celotex TB,GA and XR

Kingspan and Celotex both offer a range of multipurpose insulation boards. Kingspan has TP10, TW55 and TF70, and Celotex has TB, GA and XR.

Criteria	Celotex TB, GA, XR	Kingspan TP10/TW55/TF70
Thermal Conductivity	0.022 W/m K	0.022 W/m K
Material Composition	PIR foam core with low emissivity foil facings on both sides	PIR foam core with low emissivity foil facings on both sides
Durability	Good – Not designed for high-compression areas like warm deck flat roofs, however excellent for use in floors, walls, pitched roofs and cold deck flat roofs	Good – Not designed for high-compression areas like warm deck flat roofs however excellent for use in floors, walls, pitched roofs and cold deck flat roofs. Kingspan does have TR26 & TR27 available as flat roof boards.
Cost	Lower	Higher (around double compared to Celotex)
Application	TB: Thin board, suitable for reducing thermal bridging. GA: Walls, floors and roofs XR: Where thicker insulation is required.	TP10: Pitched roofs TW55: Timber & steel frame walls TF70: Floors

Shop Celotex TB4000 →Shop Celotex GA4000 →Shop Celotex XR4000 →

What is the best multi-purpose insulation?

Celotex and Kingspan multipurpose insulation options offer the same thermal performance and are both made from PIR foam with foil facings. However, Kingspan has other board options such as TR26 & TR27 which have a higher compressive strength making them suitable for warm deck insulation applications.

However, between the Celotex & Kingspan multi-purpose PIR boards, Celotex will be the better choice as they are significantly cheaper whilst offering a near-identical performance.

Celotex vs Kingspan, which is cheaper?

When it comes to insulation, and everything in life, money is often the biggest driving factor. How much you spend on insulation may be the difference maker between finishing your project on-time or late.

Upfront costs are essential, however, they aren’t the only thing you need to consider. You also need to look at the long-term costs and potential energy savings down the line.

Upfront costs – Price per Square Meter

Celotex typically ranges between £15-£30/m².

Kingspan typically ranges between £25-£40/m².

Long-term costs – Energy Efficiency & Savings

No matter which brand you opt for, choosing to insulate your home will help you save on energy costs – with potential reductions up to 50% saving anywhere from £300 to £500 a year for an average home.

Kingspan generally has a higher thermal performance, which if you’re insulating a shallow cavity, will allow you to achieve a better thermal performance and ultimately save more.

Celotex vs Kingspan – which is right for your project?

The choice between Celotex and Kingspan depends on your priorities and budget.

If you’re on a budget and looking for an affordable, cost-effective solution, Celotex is a great choice. If you’re looking for superior performance and happy to spend extra on insulation for long-term results, Kingspan is the choice for you.

Both brands are easy to install and deliver excellent thermal efficiency, allowing you to achieve a warmer, more energy-efficient home regardless of your choice.

If you need any help with your insulation project, please don’t hesitate to reach out to us today. UKFR is a family-run business, and with extensive knowledge of insulation and flat roofing, we’re here to help you find what you need for your project.