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Celotex  |  SKU: TC1090

6 Boards x 90mm Celotex Thermaclass Cavity Wall 21 Insulation - 1190mm x 450mm

£74.17 Ex VAT
£89.00 Inc VAT

Celotex Thermaclass 21 is a 90mm tongue-and-groove PIR insulation board designed specifically for 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.


Thermaclass Cavity Wall 21 is an easy to install, high thermal performance polyisocyanurate (PIR) insulation board for full fill cavity wall applications, with a thermal conductivity of 0.021 W/m.K. It can be installed with up to a 10mm residual cavity (to support ease of installation and accommodate mortar squeeze) or as a full fill solution with no residual cavity.

The boards have a low emissivity foil facing to each side and feature an engineered tongue and groove joint profile, helping to ensure a continuous layer of insulation to maximise thermal performance and provide protection from wind driven rain.

Thickness: 90 mm
Length: 1190 mm
Width: 450 mm
Coverage: 3.21 m²
Thermal conductivity: 0.021 W/mK
No Boards: 6
Country Origin: UK
  • Size
    1190mm x 450mm
  • Coverage (m²)
    3.213
  • Thickness
    90mm

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.

Thickness: 90mm