Celotex Saint-Gobain Insulation UK offer a range of products for thermal and acoustic Insulation. With a strong focus on innovation, their products are of high quality and the company has over 90 years of experience.


What Is Celotex?


Celotex is a multi-purpose insulation board that can be used around the home for insulating roofs, walls and floors and they come in a range of sizes and thicknesses.


Celotex Insulation Guide


What is Celotex Made From?

Celotex insulation boards are PIR, (polyisocyanurate), which is produced as foam and used as rigid insulation. This rigid core is usually sandwiched between two aluminium foil facings that are high performance, thus creating a tough, hard wearing yet lightweight insulation board. Performance is high while reducing building or renovating costs. The way in which the boards are made is easy on the environment and has a low impact on global warming.


Is Celotex Fireproof?


There is no insulation that is fully fireproof, but there are some insulation boards available which are classed as “fire resistant” or “fire proof”, which means the material used in them slows the spread of fire. They are specially designed to resist high temperature and ensure no toxic smoke is released if it does encounter flames.


Celotex products will burn if exposed to a fire of sufficient heat and intensity. All organic materials when burnt release toxic gases. Any fire should be fought by trained firefighters according to the combustible materials present and using breathing apparatus. Cardboard and plastic packing materials are combustible too. We advise to store the boards away from all possible sources of ignition.


What can Celotex Insulation be used for?


Celotex insulation can be used for walls, flooring and roofs in homes and other buildings.


We’ve put together this handy table to help you compare the different Celotex products that we sell.


Product Use Size Thermal Conductivity W/mK Available Sizes
Celotex CW4000 Insulation Board Cavity Wall - specifically for use in partial-fill cavity wall applications. 1200mm x 450mm 0.022 50mm
Celotex XR4000 Insulation Board Multi-purpose -
Pitched Roofs
Flat Roofs
Solid Masonry Walls
Timber Framed & Steel Framed Systems
1200mm x 2400mm 0.022 120mm
Celotex PL4000 Thermal Insulation Board The 'underneath' layer of insulation in between and under rafter and joist applications
Insulating solid masonry walls
Timber frame lining applications including stud wall insulation
1200mm x 2400mm 0.022 25mm/12.5mm
Celotex TB4000 Insulation Board Multi-purpose -
Pitched Roofs
Flat Roofs
Solid Masonry Walls
Timber Framed & Steel Framed systems
1200mm x 2400mm 0.022 25mm
Celotex GA4000 Insulation Board Multi-purpose -
Pitched Roofs
Flat Roofs
Solid Masonry Walls
Timber Framed & Steel Framed systems
1200mm x 2400mm 0.022 50mm


Here we will take a closer look at some of the uses in more detail.


Using Celotex For Floor Insulation


Insulating floors is important for keeping heat in the property and keeping feet warm in the winter as well as being effective at adding a sound barrier between upper and lower floors.


The following Celotex Insulation boards can be used for solid floor insulation, with concrete or screed flooring.


The Celotex boards are laid on top of existing flooring and then covered by your chosen floor finish. It’s a cost-effective heat-retention measure and in the long term, can save you money on energy bills, making it a very worthwhile investment.


For further information on insulating your floors, read our floor insulation guide.


Using Celotex For Wall Insulation


Insulating walls can be done in three ways:

  • Cavity walls
  • Interior walls
  • Exterior walls


House Construction Courtesy of Milivoj Kuhar


Cavity Wall Insulation


Celotex CW4000 Insulation Boards can be used for cavity wall insulation. This product is aimed specifically at partial fill cavity wall applications.


Internal Stud Wall Insulation


One of the best ways to insulate internal solid walls is by using stud wall insulation. By packing insulating materials between or over the timber frames, before the wall is finished, you can effectively insulate the area.


Solid External Wall Insulation


External wall insulation can help your home retain energy and heat, reducing draughts and increasing the lifetime of a wall. They don’t cause disruption in the home during installation either and so can be applied to houses that have already been built.


The following Celotex products can be used for exterior wall insulation.


Brick Wall


Using Celotex For Roof Insulation


Roof insulation can be applied in a few different ways and can help with the energy efficiency of a building. The types of roof insulation are:


  • Loft insulation
  • Pitched roof insulation
  • Flat roof insulation


Using Celotex For Loft Insulation


Insulating your loft is one of the easiest and most effective ways to save on household bills and increase energy efficiency.


For more information on the do’s and don’ts of loft insulation, check out our guide.


Using Celotex For Pitched Roof Insulation


Pitched roof insulation is used in situations where loft insulation is not practical. You can use boards or foil.


The following Celotex products can be used for pitched insulation:

  • Celotex XR4000
  • Celotex TB4000
  • Celotex GA4000


Row of Housing


Using Celotex For Flat Roof Insulation


Flat roofs can typically lose a lot of heat. Spaces such as garages, extensions and utility rooms should all be insulated properly to increase the energy efficiency of the entire home or building.

Our guide on flat roof insulation can help answer questions around the installation process.


What Is The Thermal Conductivity Of Celotex?


Thermal conductivity is 0.022W/mK for each of the Celotex products we sell.


How Long Does Celotex Last?


Celotex, if left undisturbed once installed can be expected to last around 60 years.


Is Celotex Waterproof?


Celotex is moisture resistant. This means it does not absorb water as it has a closed cell structure. This ensures the thermal performance and durability of the product is retained over time.


How Should Celotex Be Stored?


Celotex boards should be stored flat and clear of the ground, in a dry place. If you are storing the boards along with other materials or under tarpaulins, be careful of rope damage or dents from other items.


How Do I Install Celotex Insulation?


Celotex insulation should always be installed in accordance with the manufacturer’s guidance. We also have a number of guides available.


Celotex boards should not be installed in temperatures below 4°C.


When cutting Celotex boards, wear protective face masks, eye protection and sue dust extraction equipment. If your skin is sensitive to fibre irritation, apply a  barrier cream to exposed areas before handling.


Benefits Of Using Celotex Insulation


The benefits of using Celotex insulation are as follows:


  • Better thermal efficiency per mm than many other insulation materials
  • A lower environmental impact that other typical PIR manufacturers
  • An expansive product range suitable for pitched and flat roofs, walls and floors
  • Product solutions for both new builds and renovations or refurbishments
  • Lightweight
  • Low thermal conductivity offering better U-Values and some of the thinnest solutions
  • Industry leading


What If Celotex Is Not Available?


Occasionally we are required to substitute and supply an alternative. When this happens we have a number of excellent brands to choose from, including RecticelKingspan and Kooltherm.


If you need any help picking the right product, call our experts on 0113 245 9191 or contact us via this website.


Whether it’s a DIY or trade project, we offer insulation products to suit a range of uses.