50mm Kingspan Kooltherm K5 External Wall Insulation Board

50mm Kingspan Kooltherm K5 is a premium external wall insulation board engineered for superior thermal performance on masonry walls. Built with a fibre-free, rigid thermoset phenolic core, this product delivers exceptional results for external wall insulation systems and thin coat rendering applications.

The 50mm K5 board works seamlessly with both traditional and lightweight polymer-modified renders. Installation happens entirely from the outside, allowing you to upgrade your property's thermal envelope without disrupting internal spaces.

As one of the market's thinnest external wall insulation board (EWI) options, it maximises internal space—essential for properties where internal insulation isn't viable.

This board features mineral glass facings bonded during manufacturing and achieves a certified thermal conductivity (lambda) of 0.022 W/mK. The phenolic core delivers outstanding thermal efficiency using a zero Ozone Depletion Potential (ODP) blowing agent with minimal Global Warming Potential (GWP).

Kingspan Kooltherm K5 50mm exceeds Building Regulations requirements by providing exceptional thermal performance at reduced thickness. It outperforms EPS, XPS, and mineral wool alternatives, delivering higher insulation values in a thinner profile.

Each board measures 1200mm x 600mm x 50mm, offering lightweight handling and straightforward installation.

Product specification

• Brand: Kingspan
• Model: 50mm K5 Single Board
• Thickness: 50mm
• Length: 1200mm
• Width: 600mm
• Weight: 0.57kg
• Dimensions: 1,200mm x 600mm x 50mm
• Board Coverage: 0.72m2 per board
• Pack Coverage: 7.2m2
• Pack Quantity: 1 board
• Compressive Strength: 100kPa
• Density: 35kg/m3
• Thermal Conductivity: 0.022 W/mK
• R-Value: 2.50m2K/W
• Material: Rigid thermoset phenolic insulation
• Profile: Square edge
• Colour: Light shade of red
• Fire Classification: Euroclass C-s2,d0
• Finish: Mineral glass coatings
• Application Temperature: from +5 °C to +25 °C
• Applications: External insulation for masonry walls
• BBA Certified: Yes
• Features: Thinnest commonly used External Wall Insulation Board
• Manufacturer: Kingspan Kooltherm® K5

Application

Installation of Kooltherm K5 boards must follow manufacturer guidelines, which outline comprehensive design and application procedures. For best performance, attach boards to your substrate (masonry or timber) using Premium Basecoat combined with metal screw mechanical fixings.

After securing boards to the external wall, apply a protective outer layer—either a mortar basecoat or netting cover—to guard against excessive heat, moisture, and UV damage. Complete the system with a protective render topcoat. Consult our comprehensive installation guide for detailed step-by-step instructions.

Storage Instructions

Shelf Life: Refer to the manufacturer's expiry date. Storage Conditions: Store in a dry location, in the original packaging, and away from excessive heat or UV light.

Applications

• · External wall insulation systems:
• · Solid brick and block walls.
• · Cavity block and brick walls.
• · Thin coat rendering.
• · Cavity brick walls.
• · Cavity dense block walls.
• · Insulated render systems.
• · Steel-framed walls
• · Timber-framed walls.

Kingspan Kooltherm K5 Installation

We recommend

1. Adhesive and Base-Coat Render: EWI-225 Premium Basecoat Render Adhesive 25kg,
2. Rendering Mesh: Orange Fibreglass Rendering Mesh Roll,
3. Priming Paint: EWI-333 Top Coat Primer,
4. Top Coat Thin Coat Render: EWI-075 Silicone Render.
5. Plastic Fixings: 90mm Insulation Panel Fixings Plastic Pin,
6. Metal Fixings: 90mm Insulation Panel Fixings LMX10 Metal Pin Hammer Fix,
7. Base Track: 50mm Aluminium Base Track | 2500mm length profile,
8. Render Beads and Profiles

What is Phenolic Insulation?

Kingspan K5 Phenolic insulation, including our Kooltherm range, represents some of the most thermally efficient insulation materials on the market. A specialised manufacturing process creates a rigid thermoset foam core sandwiched between two facing layers, such as low-emissivity composite foil.

Phenolic insulation enables you to achieve low target U-values with minimal insulation thickness, making it perfect for projects demanding high performance and space-saving solutions.

Info

Browse our comprehensive Kingspan Products range and filter by thickness or coverage using the left-hand side options. For guidance on product suitability for your specific project or to request a quantity discount quotation, contact us by phone on +4402038839057, email sales@insulationbee, or use Live Chat for the lowest UK Kingspan insulation prices.