Kingspan Kooltherm K103


Premium performance rigid Phenolic floor insulation board

Replaced 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 options


Availability Indicators

Kingspan Kooltherm K103 is sent out from depots nationwide and is subject to the Local Depot Delivery minimum order levels and delivery charge thresholds.

Limited stock of the most popular boards sizes may be held at some of our larger depots, and thus, available on shorter lead times than the availability rating suggests.

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 may vary.

  • 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

Floor insulating board

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

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

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

Product Properties

Thickness25mm to 150mm

Product Performance

Thermal Conductivity0.019 W/mK 
Compressive Strength120 kPa at 10% compressionBS EN 826:2013
Vapour Resistance> 370 MNs/gmBS EN 12086: 1997 / I.S. EN 12086: 1998
Nominal Density35 kg/m³ 

Product Variants

ProductThicknessThermal Resistancekg/m²
Kingspan Kooltherm K103 25mm25mm1.30 m²K/W1.08 kg/m²
Kingspan Kooltherm K103 40mm40mm2.10 m²K/W1.60 kg/m²
Kingspan Kooltherm K103 50mm50mm2.60 m²K/W1.95 kg/m²
Kingspan Kooltherm K103 60mm60mm3.15 m²K/W2.30 kg/m²
Kingspan Kooltherm K103 70mm70mm3.65 m²K/W2.65 kg/m²
Kingspan Kooltherm K103 75mm75mm3.90 m²K/W2.83 kg/m²
Kingspan Kooltherm K103 80mm80mm4.20 m²K/W3.00 kg/m²
Kingspan Kooltherm K103 90mm90mm4.70 m²K/W3.35 kg/m²
Kingspan Kooltherm K103 100mm100mm5.25 m²K/W3.70 kg/m²
Kingspan Kooltherm K103 120mm120mm6.30 m²K/W4.40 kg/m²
Kingspan Kooltherm K103 130mm130mm6.80 m²K/W4.75 kg/m²
Kingspan Kooltherm K103 140mm140mm7.35 m²K/W5.10 kg/m²
Kingspan Kooltherm K103 150mm150mm7.85 m²K/W5.45 kg/m²

While we have provided Thermal Resistance values for all thicknesses on the Kingspan Kooltherm K103 datasheet, some thicknesses may not be readily available.