Celotex XR4120 Insulation Board 120mm x 1200mm x 2400mm

£42.17 £35.14
In stock
Product Description

Celotex XR4120 is a multi-application polyisocyanurate (PIR) insulation board used to eliminate cold spots that occur from a lack of insulation. Featuring foil facings, the insulation boards minimise heat loss by creating a thermal barrier. They can be used for roof, wall and floor applications.

Size: 120mm x 1200mm x 2400mm

Other available thicknesses: 25mm, 30mm, 40mm, 50mm, 60mm, 70mm, 75mm, 80mm, 90mm, 100mm & 150mm



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 XR4120? 

Celotex XR4120 provides long-term insulation and energy-saving solutions for buildings. By minimising heat loss, you can eventually expect reduced heating bills. These boards achieve low U-values even with the smallest thickness and are ideal for speedy installation. The material is easy to handle and cut and has been manufactured to the highest standards. It has a BBA (British Board of Agreement) certificate as fit for use in defined roof, wall, and floor applications as well as a BRE (Building Research Establishment) Green Guide Rating of A.


These insulation boards are environmentally friendly and have been created with a blowing agent with low global warming impact and zero ozone depletion potential. 

Features and benefits of Celotex XR4120: 

  • Excellent thermal performance with a thermal conductivity of 0.022 W/m.K, reducing the thickness of insulation required to hit the target U-value.
  • Low emissivity foil facing provides improved thermal performance in sealed cavity air spaces, improving the achievable U-value.
  • Easy to install – Celotex boards are light and rigid assisting with ease of transportation, handling, and fitting.
  • BBA certified – Celotex XR4000 has been assessed by the BBA as fit for use in defined roof, wall, and floor applications if installed, used, and maintained as set out in the certificate.
  • Celotex XR4000 achieves a BRE Green Guide Rating of A, which can assist in demonstrating environmental performance in your BREEAM assessments.
  • Lightweight 2400 x 1200mm boards.
  • Low emissivity foil facing.

Applications for Celotex XR4120 insulation boards: 

  • Ground floor - concrete slab
  • Ground floor - suspended timber joist
  • Ground floor - beam and block
  • Upgrading existing concrete slab floor
  • External wall - timber frame sheathing
  • External wall - between timber frame studs
  • Pitched roof - over timber rafters
  • Pitched roof - sarking
  • Pitched roof - between timber rafters
  • Pitched roof - loft insulation - between and over timber joists
  • Flat roof - balconies and terraces over timber joists
  • Flat roof - between timber joists

Find out more about the brand as well as other insulation products with our Celotex buyer’s guide. 

Data Sheet (200.50 kB)
Customer Questions
Can you walk on Celotex XR4120 insulation boards?
This board is not suitable to walk directly over. Celotex GA4000 AND XR4000 boards would require a chipboard or OSB board to be placed over the top, which would spread any weight evenly and protect the board from getting damaged.
Can you walk on Celotex insulation boards?
This board is not suitable to walk directly over. Celotex would require a chipboard or OSB board to be placed over the top, which would spread any weight evenly and protect the board from getting damaged.
Can I lay vinyl flooring straight onto insulation boards?
No it would be recommended to put a thin OSB or plyboard over the top of Celotex before you lay any flooring. This will help spread the weight of people walking on it which also helps to stop the board deforming overtime.
What is the fire rating?
Celotex XR4000 has a Euroclass F Reaction to Fire classification, according to BS EN 13501-1
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More Information
Supplier Part NumberXR4120
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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