External walls form the envelope of any building, protecting everything inside. There are many types of external wall insulation solutions that can meet your project requirements.

They also cover the greatest surface area, making them a prime area for heat loss –  about a third of all the heat lost in an uninsulated home escapes through the walls.1

With ROCKWOOL external wall insulation and solutions, living spaces can be made warm, energy efficient and compliant with modern building standards – as well as gaining additional benefits in terms of acoustics, indoor comfort and fire safety. 


Discover the importance of insulation for exterior walls, and the positive impacts it can bring. 

FirePro® SP FireStop EN

Introducing FirePro® SP FireStop EN – a new linear cavity fire stopping solution from ROCKWOOL delivering up to 120 minutes integrity and insulation*.

SP FireStop EN is tested in conjunction with steel frame systems, composite panels and masonry constructions – for vertical or horizontal installations.

*Subject to the application

SP Fire Stop Black Foil Slabs

External Wall Insulation Products

Why do we need external wall insulation?

The building envelope is where heat loss commonly occurs, and the outside walls are responsible for a large percentage of the heat loss.

External wall insulation can significantly reduce heat loss – improving the building’s energy efficiency, as well as cutting emissions and reducing fuel costs. 

If you start your project thinking ‘fabric first’ and install the insulation correctly from the start, you may receive a higher energy performance certificate (EPC) rating. A good EPC rating can allow developers and housebuilders to make their properties more profitable as well as commercially appealing to buyers.      


Key benefits of external wall insulation:

  • Less heat loss
  • Lower energy bills
  • Protected building structure
  • Lower temperature fluctuations
  • Reduced condensation

Calculator and savings

The exact costs and savings from external wall insulation will depend on the size of the area being insulated and how much insulation is required. It is important to address the external wall as a complete system, and take into consideration thermal bridging. For example, around windows, doors, and floors. You can – of course – also decide to go above and beyond what is required by minimum regulations. 

Use our U-Value Calculator to work out the thermal performance of your walls. ROCKWOOL can also provide technical support in different ways, using online digital tools or calculations from our technical experts. 


“There are many simple yet effective ways to insulate your home, which can significantly reduce heat loss while lowering your heating bills.”

Energy Savings Trust


U-Value Calculation Tool
ROCKWOOL boasts excellent thermal performance both in winter and summer. Stone wool slabs can add significant mass to the building envelope, ensuring summer comfort. The fibres in the tightly butted slabs effectively knit together, significantly reducing heat loss that would otherwise be caused by gaps between slabs.

Erica Bazzini

Global Product Manager, ROCKWOOL Group

Case Studies


The problem

Wilmcote House flats, an iconic Portsmouth landmark, had become blighted by mould, damp and condensation. 

Many people living in its three connected blocks – across 100 maisonettes and 11 ground-floor flats – were in fuel poverty, and residents were not typically heating their homes to the comfort temperature of 18°C set by the World Health Organisation (WHO).


The solution

Renovation aimed to ease fuel poverty by making the buildings naturally warmer and less susceptible to damp – with a target to reduce heating demand by 90 per cent. 

Meanwhile, a deep retrofit was launched to extend the lifetime of Wilmcote House by another 30 years. 


The result

ROCKWOOL external wall insulation helped to reduce draughts, condensation and mould. Thermal performance and air tightness were improved thanks to the fitting of a 300/400mm zone fixed to external steel frames, which were newly assembled.

Wilmcote House project completed
It’s about future-proofing the property and moving away from the sticking plaster approach.
Due to the fabric improvements, we’re now more confident that the residents don’t need as much heating in their properties. In fact, we’re looking to take out some of the existing storage heaters so that there is a maximum of two per property — one in the lounge and one in the downstairs hall.

Steve Groves

Head of Building Maintenance at Portsmouth City Council
Read more about Wilmcote House
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Routes to Compliance

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EWI System Holders Guide

To be updated
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Rainscreen Acoustic Reference Guide

Download our guides

Financial support

Check the Energy Savings Trust website to see whether there are any financial support schemes available for external wall insulation.

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