Celotex Thickness Guide

celotex thickness


Are you looking for a guide to different Celotex insulation boards thicknesses?

There are a lot of different types of insulation boards and thicknesses available on the market today. Manufacturers don't always make it easy to understand the differences between them and which one will work best for your particular application.

This guide breaks down the most popular types of Celotex Insulation board thicknesses so you can make an informed decision about which board is right for you.

What thickness do Celotex insulation boards come in?

Celotex insulation boards come in a variety of thicknesses, depending on the specific board.

For the sake of simplicity, they are all denoted by a 6 digit product code. The first 4 digits are just for product identification, while the last 2 digits denote the thickness of the board in mm.

So, for example, a Celotex GA4000 board with a code of GA4050 would be 50mm thick.

Below we will discuss the 5 most common Celotex insulation product ranges and their corresponding product codes and thicknesses.

They are Celotex GA4000, TB4000, XR4000, CW4000, and PL4000

First, lets discuss the multi purpose insulation board ranges: TB4000, GA4000XR4000


Celotex General Purpose PIR Insulation Board Thickness

Celotex TB4000

TB4000 means "thermal bridging". These are thinner boards generally used to overcome cold spots and for overcoming thermal bridging in timber frame and roof insulation.

Celotex TB4000 is available in thicknesses from 20mm to 40mm

Celotex GA4000

GA4000 means "general application boards" These sizes are the most common Celotex boards as they are suitable for numerous applications.

Celotex GA4000 is available in thicknesses from 50mm to 100mm,

Celotex XR4000

Celotex XR4000 is the thickest insulation that Celotex offers. They are used in situations when a thicker board is needed to meet the required u values.

Celotex XR4000 is available in thicknesses from 110mm to 200mm.

Apart from the general thermal insulation boards above, there are two other popular products in the Celotex range: Celotex PL4000 and Celotex CW4000

Celotex Insulated Plasterboard Thickness

Celotex PL4000

Celotex PL4000 is their high performance insulated plasterboard product which consists of a single layer of plasterboard bonded to their PIR insulation board. This creates a very cost effective insulation and plasterboard product which reduces installation time when plastering and insulating walls. It is especially popular in existing buildings as it can lead to cost savings over other options.

Like all Celotex insulation boards, PL4000 has low global warming potential, zero ozone depletion potential, and low thermal conductivity.

Celotex PL4000 is available in thicknesses from 25mm to 65mm for the Insulation board and an extra 12.5mm for the Plasterboard. For a total thickness of between 37.5mm and 77.5mm


Celotex Cavity Wall Thickness

Celotex CW4000

Celotex CW4000 is their high performance cavity wall insulation board. They are conveniently sized boards specifically designed to fit in between cavity wall ties in the cavity of masonry walls. Like all the Celotex range, the foil facings are low emissivity foil facings which provide better insulation and lower u values.

Celotex CW4000 is available in thicknesses from 40mm to 100mm

Celotex insulation board product codes and thickness explained

Celotex uses product codes to denote the thickness of its insulation boards. As you'll see below, the different product codes all relate to the thickness of the board. So if you're looking for a specific board thickness, just look out for the corresponding product code.

Celotex TB4000 thermal bridging board

  • TB4020: 20mm
  • TB4025: 25mm
  • TB4030: 30mm
  • TB4040: 40mm

celotex tb4000 thickness

Celotex GA4000 Insulation

  • GA4050: 50mm
  • GA4060: 60mm
  • GA4070: 70mm
  • GA4075: 75mm
  • GA4080: 80mm
  • GA4090: 90mm
  • GA4100: 100mm

celotex tb4000 thickness

Celotex XR4000 Insulation

  • XR4110: 110mm
  • XR4120: 120mm
  • XR4130: 130mm
  • XR4140: 140mm
  • XR4150: 150mm
  • XR4165: 165mm
  • XR4200: 200mm

celotex xr4000 thickness

Celotex PL4000 Insulated Plasterboard

  • PL4025: 25mm (37.5mm including plasterboard)
  • PL4040: 40mm (52.5mm including plasterboard)
  • PL4050: 50mm (62.5mm including plasterboard)
  • PL4060: 60mm (72.5mm including plasterboard)
  • PL4065: 65mm (77.5mm including plasterboard)

celotex pl4000 thickness

Celotex CW4000 Cavity Wall Insulation

  • CW4040: 40mm
  • CW4050: 50mm
  • CW4060: 60mm
  • CW4075: 75mm
  • CW4085: 85mm
  • CW4100 100mm.

celotex cw4000 thickness


What's the difference between Celotex TB4000, GA4000, XR4000?

According to the Celotex website:

"TB4000 is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing and low global warming impact.. it can be considered for floor, walls, and roof applications."


"Celotex GA4000 is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing. It can be considered for roof, walls, and floor applications"


"Celotex XR4000 is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring low emissivity foil facings and low global warming impact. It can be considered for roof, walls, and floor applications"

In other words, they are all the exact same product.

They all have foil facings, they all have zero ozone depletion potential and low global warming potential according to the bre green guide.

The only difference between the three Celotex products is the thicknesses that they are available in. That's it!

Some people feel it's time Celotex changed their marketing and simplified the unnecessary usage of different product codes for what is essentially the same product but once it's explained it's simple to understand.

Frequently Asked Questions

  • What is the thinnest Celotex?

The thinnest Celotex board is TB4000 which is available in a minimum thickness of 20mm. It is designed to be used in overcoming thermal bridging and to eliminate cold spots

  • What is the thickest Celotex?

The thickest Celotex board is the Celotex XR4000 which is available in thicknesses from 110mm to 200mm. It is used as a general application board and is popular in flat roofs.

  • What is the difference between Celotex GA4000, and XR4000?

In short, very little! The GA4000 is simply a board that is available in smaller thicknesses, while the XR4000 is available in larger thicknesses. They are both designed as general application boards and can be used for a variety of applications.

  • What thickness of Celotex do I need?

The answer depends on a variety of factors including the specific application, the budget, and the desired U value. However, as a general rule of thumb, you should always choose the thickness of the board that provides the best possible insulation for your needs while still meeting any Building Regulations requirements. It is always better to opt for a thicker board as this will provide better insulation but remember that you may also need to factor in enough space to allow for an air gap depending on the application and the thicker the board the more it will cost.


In conclusion, Celotex boards are a cost-effective way of insulating your home and reducing your heating bills. The different boards are available in a range of thicknesses to suit your specific needs, and with a range of product codes to denote the thickness, it's easy to find the right board for the job. Remember to always choose the board that provides the best possible insulation for your needs while still meeting any Building Regulations requirements.






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