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Kingspan TW50 Thermawall Cavity Wall Insulation Boards

Kingspan's popular polyisocyanurate products are available in most popular thickness’s from the manufacturer, in which case short lead-times apply. The most popular board sizes may be available from stock.

Kingspan TW50 available in most popular thickness’s from the manufacturer, therefore short lead-times apply. This Thermawall Range includes the following readily available product thickness's 25mm, 30mm, 40mm, 45mm, 50mm, 60mm, 70mm, 75mm and 100mm. Manufactured to order are the following thickness's 55mm, 65mm, 80mm and 90mm

Product Functions

Thermawall TW50 performance rigid PIR boards used for insulation of cavity walls and timber and steel framing systems.

Thermawall TW50 Range comprises performance rigid PIR boards used for Insulating partial fill cavity walls. These boards are faced on both sides with a low emissivity composite foil facing that is highly resistant to the transmission of water vapour

Common applications for this product include ...
Cavity Wall (Partial Fill) Applications, Single Timber Frame Wall Lining, Steel Stud Frame Walls, Timber Frame Wall Lining, and Timber Frame Walls Sheathing

Product Description

The Front Facings

TW50 is faced on both sides with a low emissivity composite foil facing which is highly resistant to the transmission of water vapour. This reflective, low emissivity surface can effectively double the thermal resistance of the cavity in which the board is placed.

The Core

The core of TW50 is manufactured from trademarked Nilflam technology (a high performance CFC/HCFC free polyisocyanurate (PIR) based formulation). TW50 has a typical density of 32 kg/m3.

TW50 is manufactured without the use of CFCs/HCFCs and has zero Ozone Depletion Potential (ODP).

Compressive Strength

Typically exceeds 140 kPa at 10% compression when tested to BS EN 826: 1996 (Thermal insulating products for building applications. Determination of compression behaviour).

Water Vapour Resistance

Modified to include board facings, the boards achieve a resistance far greater than 100 MN.s/g, when tested in accordance with BS 4370–2: 1993 (Methods of test for rigid cellular materials. Methods 7 to 9)
Where additional vapour control is required an appropriate surface treatment should be applied over the completed insulated wall area (see ‘Water Vapour Control’)


If correctly applied, the TW50 Board has an indefinite life. Its durability depends on the supporting structure and the conditions of its use.

Resistance to Solvents, Fungi & Rodents

The insulation core is resistant to short–term contact with petrol and with most dilute acids, alkalis and mineral oils.
However, it is recommended that any spills be cleaned off fully before the boards are installed. Ensure that safe methods of cleaning are used, as recommended by the suppliers of the spilt liquid. The insulation core is not resistant to some solvent–based adhesives systems, particularly those containing methyl ethyl ketone. Adhesives containing such solvents should not be used in association with this product.

Damaged boards or boards that have been in contact with harsh solvents or acids should not be used.

Fire Performance

TW50, when subjected to British Standard fire tests, achieves the results given below.
Test - BS 476–3: 1958 (External fire membrane adopted exposure roof test)
Result - SAA rating
Test - BS 476–7: 1997 (Fire tests on building materials and structures. Method of test to determine the classification of the surface spread of flame of products
Result - Class 1 rating

Product Benefits

    High performance rigid PIR thermoset insulation – thermal conductivity 0.022 W/m.K
    Meets NHBC technical requirements when used with a 50 mm residual cavity
    Clear cavity is maintained –resists moisture penetration
    Can be used between studs or as an insulating sheathing
    Low emissivity foil facings significantly increase the thermal resistance of the cavity
    Unaffected by air infiltration
    Resistant to the passage of water vapour
    Easy to handle and install
    Ideal for new build or refurbishment
    Non–deleterious material
    Manufactured with a blowing agent that has zero ODP and low GWP

Product availability indicators

TW50 - Price and Availability Advisory:

Presently there are no availability restrictions, apart from manufacturing lead-times and minimum quantity order levels on the 55mm, 65mm, 80mm and 90mm boards

Excellent = Product Availability Excellent Good = Product Availability Good Fair = Product Availability Fair Poor =  Product Availability Poor Undetermined = Product Availability Undetermined
Availability relies on stock levels at closest depots and upon transport logistics to effect deliveries

Technical Data

Kingspan TW50 Cavity Wall PIR Insulation Boards

Product Code

Board dimensions

Thickness (mm)

λ Value (w/mK)

R-value (m²K/W)

U Value (W/m²K)

Weight (kg/m²)

Unit weight (kg)

Kingspan TW50 25mm 20 x 0.45m x 1.2m = 10.8m² 25 0.022 1.10 0.91 1.14 12.40
Kingspan TW50 30mm 16 x 0.45m x 1.2m = 8.64m² 30 0.022 1.35 0.75 1.30 11.36
Kingspan TW50 40mm 12 x 0.45m x 1.2m = 6.48m² 40 0.022 1.80 0.56 1.62 10.56
Kingspan TW50 45mm 11 x 0.45m x 1.2m = 5.94m² 45 0.022 2.00 0.50 1.78 10.67
Kingspan TW50 50mm 10 x 0.45m x 1.2m = 5.4m² 50 0.022 2.25 0.45 1.94 10.50
Kingspan TW50 55mm 9 x 0.45m x 1.2m = 4.86m² 55 0.022 2.50 0.40 2.10 10.26
Kingspan TW50 60mm 8 x 0.45m x 1.2m = 4.32m² 60 0.022 2.70 0.38 2.26 9.84
Kingspan TW50 65mm 6 x 0.45m x 1.2m = 3.24m² 65 0.022 2.95 0.34 2.42 7.86
Kingspan TW50 70mm 6 x 0.45m x 1.2m = 3.24m² 70 0.022 3.15 0.32 2.58 8.40
Kingspan TW50 75mm 6 x 0.45m x 1.2m = 3.24m² 75 0.022 3.40 0.30 2.74 8.88
Kingspan TW50 80mm 6 x 0.45m x 1.2m = 3.24m² 80 0.022 3.60 0.28 2.90 9.42
Kingspan TW50 90mm 4 x 0.45m x 1.2m = 2.16m² 90 0.022 4.05 0.25 3.22 6.96
Kingspan TW50 100mm 5 x 0.45m x 1.2m = 2.7m² 100 0.022 4.50 0.23 3.54 9.60
Thermal conductivity / Lambda value (W/mK) = 0.022 to 0.022 | Compressive Strength (kPa) = > 125 | Water vapour resistance (MNs/g) = > 100 | Fire Performance = Class 1 | Please Note: R-Value = Thermal Resistance; U-Value = Thermal Transmittance Co-efficient; Compressive Strength = kiloPascals; Vapour resistance = MegaNewton second gram

Product Information and Certification

Links to manufacturer's information. Click to download in a separate browser window.

Kingspan TW50 Datasheet | Kingspan Product Selector | Kingspan Design Manual | Kingspan BBA U-Value Compliancy Cert. | TW50 CE Performance Declaration

Kingspan Kooltherm® TW50 Range - Certification

Kingspan Thermawall® TW50 is manufactured to the highest standards. The cavity wall insulation comprises a high performance rigid thermoset insulation core faced on both sides with a low emissivity composite foil facing. The product is manufactured: with a blowing agent that has zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP); in accordance with the requirements of BS 4841–1; under a management system certified to BS / I.S. EN ISO9001: 2008, BS / I.S. EN ISO 14001: 2004 and BS / I.S. OHSAS 18001: 2007; by Kingspan Insulation Limited; and should be installed in accordance with the instructions issued by them

CE Marking - Kingspan has provided Decelerations of Performance for its products. CE marking is the visible sign, that the product has met the requirements of the European Norms (ENs) and is therefore compliant with the Construction Products Regulation (CPR).

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Product Installation - Kingspan Thermawall TW50

Kingspan Thermawall® TW50 is normally held in position by the wall ties used to tie the two skins of masonry together. 

Wall ties should include a retaining disc / clip and be of the double drip type, installed drip downward. 

For a solid concrete ground floor the first row of wall ties are installed in the inner leaf at 600 mm horizontal centres a minimum of one course of blockwork below the damp proof course or 150 mm below the top surface of the ground floor perimeter insulation up-stand (see ‘Linear Thermal Bridging at the Wall to Floor Junctions’ above), whichever is the lower. 

For a suspended timber floor the first row of wall ties are installed in the inner leaf at 600 mm horizontal centres a minimum of 200 mm below the top surface of the ground floor perimeter insulation up-stand.

Continue constructing the inner leaf up to the next wall tie course (450 mm above the first – usually 2 block courses). 

The next course of wall ties is positioned at the usual 900 mm horizontal centres in the UK and 750 mm horizontal centres in Ireland. 

The next course of blockwork is installed to secure the ties. 

The first row of insulation boards should now be installed between the two rows of wall ties, ensuring each insulation board is retained tight against the inner leaf and joints are lightly butted. 

Each board should be secured at a minimum of three points. Additional ties may also be required to satisfy the structural requirements of BS 5628–3: 2001 and / or to ensure adequate retention of boards or cut pieces. 

The outer leaf is then built up to the level of the top of the boards and the process is repeated. 

When insulating a gable, insulation boards should be continued 250 mm beyond the height of the top storey ceiling and a cavity tray installed above the insulation.

Excess Mortar

After raising each section of inner leaf, before installation of the insulation board, excess mortar should be removed and mortar droppings cleaned from exposed edges of the installed insulation boards. 

Use of a cavity batten or cavity board is recommended to protect board edges and maintain a clear cavity (see Figures 7 & 8 or refer to BBA Certificate 94/2992 or NSAI Agrément Certificate 03/0196).

Contact Manufacturer

Kingspan Limited

Kingspan Kooltherm Phenolic Foam, Therma PIR, and Styrozone Polystyrene range of rigid insulation boards

Pembridge, Leominster, Herefordshire, HR6 9LA

Kingspan Technical Advisory Service.

Telephone: 01544 388 601 - Fax: 01544 388 888
Email:  /
Web sites: Kingspan Home Page / Kingspan U-Value Calculator.

Contact us

Insulation Online Limited

Sales Office only:

39 Normandy Road, Worthing, West Sussex, BN14 7DX, UK

Telephone: 0333 8000 828