External Wall Insulation (EWI)

External walls, together with the roof, form the envelope of any building, protecting everyone and everything inside.

Find Products Cladding Solutions EWI Slab Downloads

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.

Find inspiration, guides and reports

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

External Wall Insulation Products

Cladding solutions

RainScreen Duo Slab®

RainScreen Duo Slab® is a stone wool insulation product specifically developed for use within ventilated cladding systems, as well as sealed systems such as curtain walling. It is a BBA-approved insulation product, that in addition to thermal insulation comfort, provides an independently-tested acoustic benefit.

Slab Products

Timber Frame Slab

ROCKWOOL Timber Frame Slab is a non-combustible stone wool insulation with dimensions specifically designed to enable quick and easy installation into timber frames.

Slab Products

Steel Frame Slab

ROCKWOOL Steel Frame Slab has been specifically designed for use in steel frame buildings. Steel Frame Slab has been engineered to meet thermal, acoustic and fire requirements in external walls.

Cladding Solutions

Cladding Roll

Cladding Roll is a stone wool insulation specifically developed for use within twin skin systems. In addition to thermal comfort, the product provides independently-tested acoustic and fire resistance properties.

Cladding Solutions

External Wall DD Slab

ROCKWOOL insulation for EWI systems - ROCKWOOL External Wall DD Slab insulation has been specifically developed for use within external wall insulation systems. Such systems can considerably enhance both the thermal and acoustic performance of a building.

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

Relevant resources

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

Learn about energy efficiency

Why choose ROCKWOOL solutions?

In using ROCKWOOL insulation, you can simplify the specification process. We offer a proven and tested comprehensive range of stone wool solutions that reduce heat loss through external walls and save energy.

ROCKWOOL benefits include²:

Fire resilience
Temperature maintenance
Noise reduction properties
Robustness
Sustainability
Water repellent and vapour permeable
Flexibility for innovative building design

ROCKWOOL external wall insulation is central to developing energy-efficient walls, and meets regulatory requirements by providing continuous insulation for residential and commercial buildings.

Fire resistance also adds an extra layer of safety. Non-combustible ROCKWOOL stone wool insulation can withstand heat above 1000°C³ – ideal during construction or renovation of high-rise buildings, which often face the greatest fire risk.

ROCKWOOL insulation is both water repellent and vapour permeable, which means it repels water, yet remains breathable, limiting the risk of condensation.

Find ROCKWOOL products

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.

Find more case studies

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

Installing

With the various solutions available for external wall insulation, there are many different installation requirements. For cavity walls you can install granulate, partial and full fill slabs, while for timber frame you need products with flexible edges.

High-density slabs or lamellas are necessary for ETICS and ventilated facades, with prefabricated sandwich panels or slabs with cut-outs best for metal walls. More detailed instructions can be obtained from the product datasheets which can be found on the product pages.

Some overall tips:

Measure your walls – measure the size of your external walls first to ensure you have enough installation material.
Choose the right product – assess the shape, size and material of your external wall to help decide on the best insulation product and installation method to use.
Consider the building use – choose the best external wall insulation whether it’s for a commercial, residential or industrial property.

Installation guides for professionals

Applications

Insulation

Cladded Façade Insulation

Cladded façade insulation is an important aspect of high performing cladded façade systems. Cladded facade insulation improves acoustics, heat loss, fire resilience and energy efficiency in buildings.

Insulation

Metal Wall Insulation

Metal wall insulation improves building performance and operating costs for constructions with metal wall systems.

Insulation

ETICS

Apply multilayer insulation ETICS solutions to the external walls of a new or existing building.

Insulation

Timber Frame Wall Insulation

Timber frame wall insulation provides strong acoustic, fire resistant and thermal properties.

Insulation

Cavity Wall Insulation

Cavity wall insulation reduces heat loss, energy use and cuts heating costs. Discover the benefits of ROCKWOOL cavity wall insulation today.

Downloads and resources

PDF

2.5 MB

Routes to Compliance

Download Brochure

PDF

830.2 KB

EWI System Holders Guide

Download Guide

PDF

609.0 KB

Rainscreen Acoustic Reference Guide

Download Guide

Download our guides

Product Documentation

ROCKWOOL Thermal Regulation Guides

More stringent thermal regulations are now in place across the UK, bringing significant changes for new and existing buildings. Download our straightforward guides today

Product Documentation

The ROCKWOOL Red Book

To help save specifiers’ time and make it easier to identify the correct insulation solutions for facades, walls, floors and roofs, ROCKWOOL has launched the new ROCKWOOL Red Book – a fully interactive guide which provides digital access to technical data, product certification and a wide range of specification support materials.