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Celotex  |  SKU: CW4050

50mm Celotex CW4050 Cavity Insulation - 1200mm x 450mm - 11 Boards

£45.68 Ex VAT
£54.82 Inc VAT

This 50mm Celotex CW4050 PIR Insulation board is designed specifically for partial-fill cavity wall insulation.

Nationwide Delivery in 3-5 WORKING DAYS

  • £50 ex VAT Delivery
  • FREE DELIVERY OVER £500

Need a next-day or named day delivery? Call Us.


This Celotex CW4050 is a partial fill insulation for masonry cavity walls. It is a high-performance rigid polyisocyanurate (PIR) material which is available in 50mm thickness and has been pre-sized so it can fit between cavity wall ties. It's suitable for use in both new and existing builds as well as extensions, making it a versatile option.

CW4050 insulation has excellent thermal conductivity value of 0.022 W/mK, and the innovative low emissive aluminium foil facing helps it to achieve impressive uValues. As a result, it's among the best-performing insulation materials available on the market, bringing you reliable long-term savings.

  • Quick & easy to install
  • High-performance partial fill PIR insulation board
  • Low emissivity foil facings
  • Improves thermal insulation performance in cavity air spaces
  • Suitable for masonry cavity walls
  • CS(10\Y)120 compressive strength (kPa)

Celotex CW4050 insulation board has been specifically sized to fit the standard wall tie spacing requirements. This means that no cutting is required, making it quick and easy to be installed. When fitted correctly, it will help you meet carbon dioxide emissions and energy use targets which have been set by the national building regulations.

Thickness: 50 mm
Length: 1200 mm
Width: 450 mm
No. Boards: 11
Coverage: 5.94 m²
R-value: 2.25 m²K/W
Thermal Conductivity: 0.022 W/mK
Maximum Weight: 1.92 kg/m² 
Certification: BA 16/5352 BBA  17/5405
Country Origin: UK


The R-value denotes the resistance to heat flow – the higher the R-value the more insulating the product is.

What's more, this sturdy PIR insulation comes with a BBA (British Board of Agrément) certificate and a BRE (Building Research Establishment) Green Guide Rating of A, which will help improve your environmental performance.

  • Thermal conductivity: 0.022W/mK, according to BS EN 13165 for factory made rigid polyurethane foam (PU) product
  • BRE Green Guide Rating: A
  • Spread of flame: Euroclass F 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.
  • Certification: BBA certified
  • Size
    1200mm x 450mm
  • Coverage (m²)
    5.94
  • Thickness
    50mm
  • Material
    PIR

Do You Ship to My Address?

We deliver to most mainland UK addresses. If you are in one of the areas listed below and are unable to checkout, please give us a call to put together a custom quote.

Northern Ireland (BT), Isle of Wight (PO30-37), Isle of Man (IM), Scottish Highlands and Orkney Isles (PA, ML, EH, KA, G, KY, PH, DD, AB, IV, KW), Outer Hebrides and the Shetland Isles (HS, ZE) will incur additional charges and may also experience delivery delays.

How Much Will My Delivery Cost?

You can work out the cost of delivery on your order before checkout by heading to our Delivery Info page.

How Long Will Delivery Take?

We aim to deliver your items in 3 - 5 Working Days unless otherwise specified (eg - Sheds and Paving Kits). After you have placed your order, we will process your order and book a delivery day - which will then be sent to you via Email.

If have a specific request, please do give our team a call on 01156976800 and we will do our best to help.

What If I Need to Return Something?

If for any reason you wish to return your purchase, we will offer a refund or an exchange as long as this is requested within 14 days of receiving your order.

A manufacturer’s restocking charge may also apply on certain products such as non-stock items, which may be up to 30% of the purchase price, and you will be notified of this amount when you request a refund or exchange.

For full information visit our Returns Policy.

Celotex

50mm Celotex CW4050 Cavity Insulation - 1200mm x 450mm - 11 Boards

£45.68 Ex VAT
£54.82 Inc VAT

This Celotex CW4050 is a partial fill insulation for masonry cavity walls. It is a high-performance rigid polyisocyanurate (PIR) material which is available in 50mm thickness and has been pre-sized so it can fit between cavity wall ties. It's suitable for use in both new and existing builds as well as extensions, making it a versatile option.

CW4050 insulation has excellent thermal conductivity value of 0.022 W/mK, and the innovative low emissive aluminium foil facing helps it to achieve impressive uValues. As a result, it's among the best-performing insulation materials available on the market, bringing you reliable long-term savings.

  • Quick & easy to install
  • High-performance partial fill PIR insulation board
  • Low emissivity foil facings
  • Improves thermal insulation performance in cavity air spaces
  • Suitable for masonry cavity walls
  • CS(10\Y)120 compressive strength (kPa)

Celotex CW4050 insulation board has been specifically sized to fit the standard wall tie spacing requirements. This means that no cutting is required, making it quick and easy to be installed. When fitted correctly, it will help you meet carbon dioxide emissions and energy use targets which have been set by the national building regulations.

Thickness: 50 mm
Length: 1200 mm
Width: 450 mm
No. Boards: 11
Coverage: 5.94 m²
R-value: 2.25 m²K/W
Thermal Conductivity: 0.022 W/mK
Maximum Weight: 1.92 kg/m² 
Certification: BA 16/5352 BBA  17/5405
Country Origin: UK


The R-value denotes the resistance to heat flow – the higher the R-value the more insulating the product is.

What's more, this sturdy PIR insulation comes with a BBA (British Board of Agrément) certificate and a BRE (Building Research Establishment) Green Guide Rating of A, which will help improve your environmental performance.

View product
Thickness: 50mm