External Wall & Cladding Insulation

External wall insulation and cladding insulation is installed on the outside of domestic and commercial buildings. We stock popular Kingspan Kooltherm insulation boards, including external K5 insulation boards and the K15 Rainscreen cladding insulation boards. These boards will improve the thermal performance of your building and reduce your energy bills. We stock a range of thicknesses from 20mm to 100mm to suit every insulation project. Browse through our catalogue of external insulation cladding to discover a long-term solution to high energy bills.


    Product filters

    • Manufacturer

    • Thermal conductivity

    • Width

    • Thickness

    • Material type


inc VAT

Want a quotation?

What Is Exterior Wall Insulation?

Homeowners and commercial site managers lose around 35% of the heat in their spaces through walls. When property owners start to invest in insulation, wall insulation is often the first thing that they look at. The right external wall insulation (EWI insulation) can eliminate a third of your energy bills and keep your space warmer for longer. 


Kingspan Kooltherm K5 External Wall Board

The Kingspan Kooltherm outside wall insulation that we offer has a fibre-free thermoset phenolic core. Phenolic foam is made from phenolic resin, a blowing agent, and an acid catalyst. 

To create the boards, Kingspan places a layer of wet phenolic foam on a glass tissue facing. Over time, the phenolic foam expands. When phenolic foam dries it becomes tacky and adheres itself to both the bottom and top facing. Kingspan applies immense heat to the board and cures it in a different oven. Cladding insulation that is made from phenolic foam is bright pink. 

Phenolic exterior wall insulation has a closed-cell formation and is very rigid yet lightweight. Kingspan Kooltherm K5 external wall boards have glass tissue facings, which increases the overall thermal conductivity of the insulation. These boards in the Kooltherm range have a thermal conductivity of between 0.020 W/mK and 0.023 W/mK. 

External Wall Insulation

Most types of wall insulation are designed for installation inside the property, either directly on the wall or between two masonry walls. External insulation is designed for installation directly on the outer walls of your home. 

Kingspan Kooltherm K5outside wall insulation will protect your home from the elements. Phenolic is resistant to moisture, which makes it excellent for people who live in high rainfall areas. You also do not have to worry about rot or fungi growth when you invest in Kingspan Kooltherm insulation boards. They have two glass tissue facings on either side, which provide extra protection against the elements. K5 has achieved a Euroclass rating of C-s1,d0, meaning it has a limited contribution to fire.

Kingspan cares about the carbon footprint of Kooltherm insulation boards. Each board is manufactured with blowing agents that have a low Global Warming Potential (GWP) and zero Ozone Depletion Potential (ODP). People who care about their environmental impact choose Kingspan Kooltherm boards to reduce the amount of CO2 that they produce and to save money on energy bills. 

Cladding Insulation 

The term cladding refers to the outer casing of buildings. External wall insulation cladding has no impact on the structural integrity of the building itself. Cladding has thermal properties and also protects the important parts of the building from outside elements like rain and snow. There is also an aesthetic element to cladding. It is most common on large, tall commercial properties that need to meet specific building requirements. 

Kingspan Kooltherm K15 Rainscreen Insulation is premium quality exterior insulation cladding. People who need thermal protection for a range of different facade systems choose this rainscreen board. It has been tested in existing structures and has achieved a Euroclass rating of C-s2,d0. It is light, rigid, and easy to handle, which is an important consideration for cladding insulation projects as the insulation often needs to be installed at dizzying heights.

Unlike Kingspan K5 which is faced with glass tissue, Kingspan K15 is faced with composite foil facings. This external wall insulation cladding is 2400mm by 1200mm, which is the industry standard size.

Frequently Asked External Insulation Cladding Questions

Is External Wall Insulation Fireproof?

All insulation materials have a Euroclass rating. The Euroclass rating was designed to combat the lack of regulation for insulation materials across Europe. External wall insulation boards have to undergo up to five different tests to achieve a Euroclass rating. Insulation that has an A1 rating is non-combustible, and insulation that has an F rating is the most combustible that a material can be. 

We stock Kingspan Kooltherm insulation boards for external walls and cladding. They contain a fibre-free thermoset phenolic foam. When fire makes contact with phenolic insulation, two reactions happen. Pyrolysis (thermal decomposition) occurs and a black scorch mark appears on the board at the point of contact. The boards in the Kooltherm range are not fireproof, but they do have a rating that lands in the middle of the scale. 

Both Kingspan Kooltherm K5 and Kooltherm K15 outside wall insulation boards have a Euroclass rating of C, which means they have limited contribution to fire.

Is External Wall Insulation Waterproof? 

Phenolic boards are water-resistant. They have a closed-cell structure and only absorb around 2% of moisture. They are also faced with either glass tissue or composite foil, which both function as an extra layer of protection for your building. 

Kingspan Kooltherm K5 and Kingspan Kooltherm K15 exterior wall insulation are designed for a range of purposes. They can protect small domestic properties and large commercial properties from the elements. We recommend phenolic external wall insulation cladding for those who want to reduce their heat consumption in areas with high rainfalls. 

How to Install Exterior Wall Insulation?

There are a few different ways to install external solid wall insulation. Kingspan Kooltherm insulation boards are faced with either glass tissue or composite foil. They are much easier to install than insulation rolls or slabs because they come with a protective cover. 

We discourage homeowners from installing outside wall installation themselves. In most cases, homeowners employ professionals to install EWI insulation. This type of insulation can also change the outward appearance of your home, which may require planning permission. 

The installation process is complicated and involves lots of different steps. Professionals have to undertake render tests, remove pipework, and protect windows before they can even think about installing external wall insulation. When it comes to high-performance thermal materials, it pays to speak to the experts.