Kingspan K103

The Kingspan Kooltherm K range comprises the thinnest commonly used insulation products for any specific U-value. With a fibre-free rigid thermoset phenolic core and a thermal conductivity of 0.018–0.023 W/m·K, Kingspan K103 panels are among the most thermally efficient insulation products and can be purchased as specialised phenolic floorboard products online.

How Is Kooltherm Phenolic Insulation Made?

The rigid thermoset foam forms an insulating core between two facing elements. At the start, wet foam insulation mix is added to the bottom layer of the facing. It then expands to meet the top layer. As it dries, the foam bonds to the facings. The foam is then heat-cured during continuous lamination.

What Is Kingspan K103, and What Types Of Floors Is It Suitable For?

Kingspan K103 is used to insulate floors below a floor slab or floor screed, and in a suspended timber floor, and below floor joists. The product is available in a wide range of thicknesses from 25mm to 150mm (please note some densities may be subjected to longer lead times due to special order specifications).

The product is available in a wide range of thicknesses from 25mm to 150mm and can be ordered in bulk or pallet quantities for larger projects (please note some densities may be subject to longer lead times due to special order specifications).

Features Of Kingspan Kooltherm K103 Floorboard

• Thermal Conductivity – All K103 boards achieve a thermal conductivity of 0.018W/mK.
• Thermal Resistance – Thermal resistance varies with thickness and is calculated by dividing the thickness of the board by its thermal conductivity. The resulting number is rounded down to the nearest 0.05 m2 K/W. Example: Insulation Thickness 100mm = Thermal Resistance 5.55m2K/W.
• Compressive strength – K103 has a compressive strength of ≥120 kPa at 10% compression, as tested in accordance with BS standards for assured structural reliability.
• Water Vapour Resistivity – typically achieves a resistivity greater than 370 MNs/gm when tested in accordance with BS EN 12086: 2013.
• Durability – If correctly installed, Kingspan Kooltherm® K103 can have an indefinite life. Its durability depends on the supporting structure and the conditions of its use.

Benefits of Kooltherm K103

• Easy to handle.
• Easy to install.
• Unaffected by air infiltration.
• Appropriate to be used for new builds and refurbishment projects, with volume discounts available for larger orders.
• Non-deleterious material, which means it is non-hazardous to health.
• Manufactured with a blowing agent that has zero ODP and low GWP.
• Resists attack by mould and microbial growth.
• Resistant to short-term contact with petrol and with most dilute acids, alkali, and mineral oils.
• Please note that all K103 Kingspan products are sold in full pack quantities only and can be purchased online from Insulation Wholesale.

Packaging and Storage

The polyethene packaging of Kingspan Insulation products, which is recyclable, should not be considered adequate for outdoor protection and should be kept under cover until installation, whether for site or residential delivery.

Insulation Wholesale is a trusted supplier of Kingspan Kooltherm across the UK, offering quotes in minutes and support for bulk or volume orders.

At Insulation Wholesale, standard delivery for 99% of products is 2-3 working days, with fast UK delivery, kerbside delivery to home or site, and project-ready stock available.

FAQ

Where to buy Kingspan K103?

You can purchase Kingspan K103 directly from us at Insulation Wholesale, where we keep a full range of K103 Kooltherm floorboards in various thicknesses, from 25 mm to 150 mm. Select thin K103 boards for limited floor height or thicker options for maximum insulation. If you are unsure which K103 Kingspan Kooltherm is right for your project, we are always happy to give friendly advice or a fast quote to make the process stress-free.

How to cut Kingspan K103?

1. Measure the exact space – say, between joists.
2. Cut your K103 with a fine-tooth saw or score it using a utility knife. Snap the panel over a straight edge, then turn it and cut the facing. This ensures clean edges and prevents damage to the facing.
3. Trim the facing on the other side so that the board remains properly faced.
4. Make sure board joints are tight butted to eliminate all gaps.
5. Press each K103 board tightly between joists or supports.
6. Use the recommended sealant to fill all small gaps and maintain continuity of insulation.

How to fit Kingspan K103?

1.Prep the Area
Clean, level, and dry the working space. When the surface is even, the Kooltherm K103 floorboard can sit properly without uneven gaps.

2.Measure and Test-Fit
Before fixing anything, place your cut Kingspan Kooltherm K103 pieces in position, ensuring they sit snugly and the edges are even. A tight fit is key – K103 Kingspan works best when there are no gaps for heat to escape.

3.Lay the Boards (Foil Side Up Unless Your System Says Otherwise)
Most floor systems use the foil-faced side down, but always follow your build spec or manufacturer’s details.
Place the K103 Kingspan Kooltherm boards in staggered rows. This prevents straight continuous joints and improves insulation performance.

4. Fix the Boards
How you secure Kingspan K103 depends on your floor build:

On Concrete Slabs:

• Lay the boards loose, fully supported underneath.
• Add a vapour control layer if required, then your screed or chipboard deck goes on top.

Between Joists:

• Place each Kooltherm K103 panel snugly between joists, and support it using battens or clips.
• Seal gaps with the recommended urethane sealant for a continuous insulation layer.

On Suspended Timber Floors:

• Fit the K103 between joists from above.
• Seal gaps using sealant.
• Support each insulation board, keeping it flush with the top of the joists. You can use:
  • timber battens side-nailed to joists, or
  • galvanised steel clips, or
  • galvanised nails. Keep nails used 40 mm proud of the joist (they stick out slightly) so they act as a support.

5.Tape or Seal the Joints
Use foil tape or the recommended jointing method to seal any visible gaps between boards. This locks the whole K103 Kooltherm layer together and boosts thermal performance.

6.Protect the Boards During the Job
Avoid leaving the insulation exposed to rain or foot traffic. Once the K103 Kingspan boards are down and checked, get the flooring layer on promptly.

7.Keep It Safe
Wear gloves whenever handling K103 Kooltherm – the foil edges can be sharp. Always walk only on the surface if it is supported, never directly on unsupported insulation.

How thick should Kooltherm K103 be for flooring?

Consider the desired heat retention rate and U-value when choosing Kooltherm K103 floorboard thickness. In many regular builds, 70 mm to 150 mm of Kingspan K103 is enough. 100 mm is the common middle-ground that gives strong thermal performance without raising the floor too much.

Thinner options like 50–70 mm K103 Kingspan can still work well in renovations with limited floor height. For new builds aiming for stricter U-values, thicker boards such as 120–150 mm Kingspan Kooltherm K103 deliver the best performance.