Celotex TB4000 Insulation Board

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Celotex TB4000 Insulation Board
Product Description

Celotex TB4000 is a lightweight polyisocyanurate (PIR) insulation board, boasting brilliant thermal performance due to the low emissivity foil facing. The boards are also light and rigid, making transportation, handling and fitting easy. 

Celotex TB4000 can be used for floor, wall and roof applications, available in thickness levels from 20mm to 40mm.



size: 1200mm x 2400mm

We are happy to help with enquiries, stock availability or any technical help you require, however for security reasons we cannot take orders over the phone. So if you need to chat give us a call on 03301231761 or email us at [email protected].

What is Celotex TB4000? 

Celotex TB4000 is a polyisocyanurate (PIR) insulation board for multiple applications, and can be used for floors, dry lining, pitched roofs and timber frames. 


The product is lightweight, yet rigid, meaning it doesn’t break easily. You’ll be able to transport and install with ease. 


Featuring low emissivity foil facings, the 2400 x 1200mm boards provide improved thermal performance and boast a BRE Green Guide Rating of A, helping you demonstrate environmental performance. They are a reliable energy-saving solution. 

What’s the difference between Celotex TB4000 and GA4000? 

When considering insulation boards, you need to understand the key components of each. The difference between Celotex GA4000 and TB4000 is the size options. They are the same low-emissivity PIR boards that can be used for applications such as roofs, walls and floors. 


However, TB4000 PIR boards are available in sizes 20mm to 40mm, whereas GA4000 boards are available in sizes 50mm to 100mm. 

Features and benefits of Celotex TB4000: 

  • Low emissivity foil facing boards with a BRE Green Guide Rating of A
  • High thermal performance with a thermal conductivity of 0.022 W/m.K, reducing the thickness of insulation required to hit the target U-value
  • Easy to install, handle and fit due to rigidity 

Applications for TB4000 insulation boards: 

  • Ground Floor - Concrete Slab (perimeter upstand)
  • Ground Floor - Beam and Block (perimeter upstand)
  • Ground Floor - Suspended Timber Joists (perimeter upstand)
  • Ground Floor - Upgrading Existing Concrete Slab (perimeter upstand)
  • External Wall - Timber Frame Internal Linings
  • External Wall - Masonry Cavity Internal Linings
  • External Wall - Solid Masonry Internal Linings
  • Pitched Roof - Below Timber Rafters
  • Pitched Roof - Above Timber Rafters
  • Flat Roof - Below Timber Joists
  • Flat Roof - Balconies and Terraces

The boards are Euroclass E Reaction to Fire classification, according to BS EN 13501-1. Products with this level of classification are not provided with a rating for smoke emission.


For more information, please read our guide on how to use Celotex

Data Sheet (205.83 kB)
Safety Data Sheet (619.33 kB)
Customer Questions
How do you cut TB400 boards?
PIR insulation can easily be cut with a standard insulation saw. Celotex TB4000 boards usually have cutting squares on them to help with sizing.
Are they fire resistant please?
Celotex TB4000 is tested to BS EN 13501-1. It achieves a classification of E. Products with this level of classification are not provided with a rating for smoke emission.
Why are some products GA and some products TB, are they the same?
Yes, they are all general purpose Celotex PIR insulation boards. TB & GA are just different thickness groups. TB, GA and XR4000 boards come in a range of thicknesses from 25mm - 150mm.
Would this insulation be suitable to go in a cavity wall with concrete block on the internal and timber cladding on the external?
The TB4000 is suitable for use in a cavity wall. You may be better with Celotex CW4000 which is the same material but the sheet sizes are smaller specifically intended for cavity walls.
Are these boards effective against damp penetration?
All Celotex products must remain dry, so all structures should be built to keep them dry. The boards should not be used in an area where there will  be damp penetration. It would be an incorrect way to use these boards.
Can these boards be applied to existing plastered walls (in this case breeze blocks) and/or skimmed plasterboard? or does the existing layer have to be removed? Also - can you plaster over these or is plasterboard on top recommended?
TB4000 is a product that must be mechanically fixed, it cannot be bonded into position. TB4000 must be finished with a mechanically fixed board such as plasterboard over the top. You cannot apply a plaster finish directly to TB4000.
Did you find what you were looking for?
More Information
SKUCelotex TB4000 Insulation Board
Supplier Part NumberTB4000
Size1200mm x 2400mm

Orders and Delivery

Free delivery if your order is over £300 ex VAT. Orders between £100 - £300 ex VAT will be subject to a delivery charge of £50 ex VAT. Please note, we are unable to accept orders less than £100 ex VAT

When ordering on line you can specify the date of delivery, however we would not be able to specify the time of delivery on that day.

• Please note that we have a number of large vehicles, including articulated vehicles that may be used for delivery. Please advise us in the comments on your order if access to the delivery address is limited.

• Due to insurance guidelines, delivery personnel are unable to enter private residences. Delivery will be as far as possible to the kerbside of the delivery address. The recipient of the products is responsible for any additional lifting once the delivery has been made. Please bear in mind that Insulation products can be bulky and / or heavy.

• The delivery driver will require a signature to confirm the goods have been received.

 † Unfortunately we, Insulation Express, cannot deliver to the Highlands & Islands of the UK. However we will be happy to deliver to a freight forwarding company on your behalf.


Returns and Refunds

In the unlikely event that you need to return an item, please contact our team on [email protected] within 14 days of accepting delivery of the item.

Restocking charges may apply. We will discuss this with you upon receipt of the cancellation request. Restocking charges will be applied where the products are no longer required AND NOT for goods returned because either defective or damaged.

We usually charge 30% of value (minimum £25.00).

Please note that we cannot accept returns on special orders. Special orders may consist of items sent via third party shipping companies or made to measure products. If you are unsure on whether or not your item is a special order, please contact us on [email protected] prior to placing the order.

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