Celotex Thermaclass Cavity Wall 21 140mm, 16 x (4 x 0.45×1.19m) = 34.27m²


Lower lambda value, higher performance, rigid Polyisocyanurate (PIR) full fill cavity wall insulation board

Comes in tongue & grooved conveniently sized boards for installation between cavity wall ties.

Includes low emissivity foil facings giving improved thermal insulation performance within a 10mm residual cavity air space.

Can be installed with up to a 10mm residual cavity or as a full fill solution with no residual cavity.

Can be used to provide energy performance of new and existing buildings.

BBA certified.

Provides reliable long term energy savings for buildings.

Thicknesses and Availability:

Available in most popular thicknesses from the manufacturer; short lead-times apply as we may need to get the products in from Celotex before delivering to site.

This Thermaclass Cavity Wall 21 Range includes the following available product thicknesses: 90mm, 115mm and 140mm.

Additional information


Special request

SKU: CELCW21140 Category:
Product ex-VAT inc-VAT  
Celotex Thermaclass Cavity Wall 21 140mm, 16 x (4 x 0.45×1.19m) = 34.27m² £1,196.22 £1,435.46

Availability Indicators

Celotex Thermaclass Cavity Wall 21 is sent out from depots nationwide and is subject to the Local Depot Delivery minimum order levels and delivery charge thresholds.

Some stock of the most popular thicknesses are held at our larger depots. In some geographic locations, depots may stock alternates, however, we will contact you to discuss before proceeding with the order.

Where products need to be brought in from Celotex, please allow approx. 1 week for delivery.

While the items are priced per pallet, in some cases we can split the pallets and supply individual packs … please contact me to discuss your requirements so I can check with the relevant depot about options of splitting the pallet.

Product availability depends upon stock levels at closest depot and delivery logistics to geographic locations.

  • Generally 1 to 3 working days for delivery
  • Generally 1 to 5 working days for delivery
  • Generally 5 to 10 working days for delivery
  • Special request or made to order item, allow extended lead times. Minimum order levels may apply.
  • Please call to check availability and approximate lead times

Delivery charges will be calculated at check-out. Please visit our Ordering From Us page for further details on minimum order levels and delivery charges. If you have any queries, please do not hesitate to contact me via our Contact Form or on 01903 899 898.

Product Application

Full fill cavity wall application insulating board

Celotex high performance polyisocyanurate (PIR) foam board, Thermaclass Cavity Wall 21, is suitable for use in cavity wall applications with up to a 10mm residual cavity or full fill cavity with no residual cavity.

Product Make-up

Core: Celotex Thermaclass Cavity Wall 21 is manufactured from rigid polyisocyanurate (PIR) using a blowing agent that has zero ozone depletion potential (zero ODP) and low global warming potential (GWP).

Facings: Faced on both sides with a low emissivity aluminium foil, autohesively bonded to the insulation core during manufacture.

Product Performance

Thermal Conductivity 0.021 W/mK  
Compressive Strength 120 kPa at 10% compression BS EN 826:2013
Vapour Resistance > 300 MNs/gm