External Wall Insulation (EWI) is the placement of insulating boards on the external surface of all the vertical walls of a building. This protects the building from fluctuating weather conditions, reduces heat losses from inside the building and will prevent external temperature changes from affecting the interior climate. EWI keeps homes warm in winter and cool in summer, ensuring a home with a pleasant atmosphere by eliminating sharp and high changes in indoor temperature. EWI will also reduce energy consumption terms of energy consumed for heating and cooling.
External Wall Insulation (EWI) is designed for a solid wall construction. You will need to seek further advice from a cavity extraction consultant for your specific needs.
Initially, the main reason for choosing an External Wall Insulation solution is that EWI will achieve higher thermally insulating results by protecting the walls from changes in outdoor temperature, taking advantage of the thermal capacity of the existing walls and more effectively avoiding thermal bridges.
Therefore, with EWI, the maximum possible reduction in heating or air-conditioning costs can be achieved. Another reason for opting for EWI is to enhance renovations. If renovating the exterior of a building, opting for an EWI solution provides great flexibility for architectural and design choices.
The disadvantage of indoor thermal insulation is the reduction of floor space in the house from the installation of the thermal insulation. In addition, the decommissioning of any objects found on the walls such as built in storage, wardrobes and radiators for example, and their subsequent reinstallation is time consuming and costly.
There is no need for full planning permission to install EWI, unless you are living in a conservation area or a listed property. However, always check with local planning authority to be sure.
What insulation boards are used for External Wall Insulation (EWI)?
The standard materials use as part of the Baumit EWI systems are Expanded Polystyrene (EPS), Mineralwool, phenolic insulation and wood fibre boards.
View our systems here.
The most common insulation thickness is 100mm, however a U Value check can indicate the appropriate thickness you will require.
A full list of thickness can be found here:
Baumit OpenTherm, EPS insulation boards
Baumit StarTherm, EPS insulation boards
Baumit Mineral Wool EWI Slab
Baumit StarTherm Nature, wood fibre board
Depending on the substrate, we offer the following fixings:
Baumit H3 Hammer Fixing, 75mm - Used on masonry
STR U 2G, 115mm - Plastic fixing used on masonry and concrete
STR H, 80mm - Metal fixing with screw thread used on timber
Depending on the size of the project, usually a two-week period is enough to complete the project.
Baumit has a variety of mineral and organic topcoat renders suitable for use will all our EWI systems, each available in a huge range of colours.
Please refer to the Baumit Topcoats leaflet for our full range of renders.
When installing EWI, all pipes should be extended and then returned into the existing outlets.
Utility services should be treated according to the guidance of the utility provider.
As part of our External Wall Insulation system range we offer a specifically design Plinth System which uses a High Density insulation Board.
For further information you can visit our guide page here.