Kingspan Insulation Kooltherm K103 phenolic floor insulation board Celotex Insulation

Kingspan Kooltherm K103

Premium performance rigid Phenolic floor insulation board.

Replaces Kingspan Kooltherm K3.

New lower Lambda Value (Thermal Conductivity) 0.019 W/mK... The most thermally efficient commonly used insulating board.

Used for insulating beam and block, concrete, and timber floors with or without underfloor heating systems.

Faced on both sides with a glass tissue based facing, autohesively bonded to the insulation core during manufacture.

Premium performance rigid thermoset fibre-free phenolic insulant.

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 Kingspan before delivering to site.

This Kooltherm Range includes the following readily available product thicknesses 25mm, 40mm, 50mm, 60mm, 70mm, 75mm, 90mm, 100mm and 150mm.

The following thicknesses are manufactured to order and may have minimum order requirements: 80mm, 120mm, 130mm and 140mm.

Product Information

General information about Kingspan Kooltherm K103

Product Application

External wall insulating board for render systems

Kingspans premium performance 'lower-lambda' value phenolic foam board, Kooltherm K103, is suitable for use in beam and dense block floors, between floor joists, suspended timber ground floors, between and under floor joists, concrete ground based floors, floating ground floors, upgrading concrete slab floors, and garage conversions.

Product Make-up


Kingspan Kooltherm K103 floor board is a premium performance fibre-free rigid thermoset phenolic insulant.


Faced on both sides with a glass tissue based facing, autohesively bonded to the insulation core during manufacture.

Product Properties

Thickness 25mm to 150mm
Board Length 2.4m
Board Width 1.2m
Board Edge Square

Product Prices

Buy Kingspan Kooltherm K103

Product ex-VAT inc-VAT
Kingspan Kooltherm K103 25mm, 12 x 1.2x2.4m = 34.56m² £413.97 £496.76
Kingspan Kooltherm K103 40mm, 8 x 1.2x2.4m = 23.04m² £366.36 £439.63
Kingspan Kooltherm K103 50mm, 6 x 1.2x2.4m = 17.28m² £320.79 £384.94
Kingspan Kooltherm K103 60mm, 5 x 1.2x2.4m = 14.4m² £315.38 £378.45
Kingspan Kooltherm K103 70mm, 4 x 1.2x2.4m = 11.52m² £293.04 £351.64
Kingspan Kooltherm K103 75mm, 4 x 1.2x2.4m = 11.52m² £321.17 £385.40
Kingspan Kooltherm K103 90mm, 3 x 1.2x2.4m = 8.64m² £283.56 £340.27
Kingspan Kooltherm K103 100mm, 3 x 1.2x2.4m = 8.64m² £305.42 £366.50
Kingspan Kooltherm K103 150mm, 2 x 1.2x2.4m = 5.76m² £298.13 £357.75

Limited stock of the most popular boards sizes may be held at some of our larger depots.

Where products need to be brought in from Kingspan, please allow approx. 1 week for delivery on stocked items and up to 3 weeks on made to order thicknesses. While Kingspan keep the majority of the popular thicknesses in stock, less popular thicknesses may carry a minimum order level.

Kingspan reserves the right to change stocked products - while we will do all we can to keep on top of changes, availability and lead times my vary.

  • Generally 1 or 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

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

Product Performance and Guides

Product Performance, Manufacturer Downloads, and Installation Guides

Product Performance

Thermal Conductivity 0.019 W/mK
Compressive Strength 120 kPa at 10% compression BS EN 826:2013
Vapour Resistance > 370 MNs/gm BS EN 12086: 1997 / I.S. EN 12086: 1998
Nominal Density 35 kg/m³
Product Thickness Thermal Resistance kg/m²
Kingspan K103 25mm 25mm 1.32 m²K/W 1.01 kg/m²
Kingspan K103 30mm 30mm 1.58 m²K/W 1.19 kg/m²
Kingspan K103 40mm 40mm 2.11 m²K/W 1.54 kg/m²
Kingspan K103 50mm 50mm 2.63 m²K/W 1.89 kg/m²
Kingspan K103 60mm 60mm 3.16 m²K/W 2.24 kg/m²
Kingspan K103 70mm 70mm 3.68 m²K/W 2.59 kg/m²
Kingspan K103 75mm 75mm 3.95 m²K/W 2.77 kg/m²
Kingspan K103 80mm 80mm 4.21 m²K/W 2.94 kg/m²
Kingspan K103 90mm 90mm 4.74 m²K/W 3.29 kg/m²
Kingspan K103 100mm 100mm 5.26 m²K/W 3.64 kg/m²
Kingspan K103 110mm 110mm 5.79 m²K/W 3.99 kg/m²
Kingspan K103 120mm 120mm 6.32 m²K/W 4.34 kg/m²
Kingspan K103 130mm 130mm 6.84 m²K/W 4.69 kg/m²
Kingspan K103 140mm 140mm 7.37 m²K/W 5.04 kg/m²
Kingspan K103 150mm 150mm 7.89 m²K/W 5.39 kg/m²

Product Certificates

Please visit the Kingspan website for product certificates.