External Wall Insulation (EWI), which is also referred to as ETICS (External Thermal Insulation Composite Systems) is a method of insulating the outside walls of either a new or existing house, and involves directly applying insulation panels to the walls of the building before finishing with a rendering system to provide protection from impact and weather.

Whilst this method of insulating your home can be expensive when compared with other alternatives, it has numerous advantages which include not only increasing thermal performance, but also improving the overall airtightness of the home by eliminating air leakage through the external walls.

As compared to insulating from the inside this method has the benefit of not reducing your floor area; you are also less likely to run into possible condensation problems as you are in effect adding a layer of protection from the elements where they hit.

Are there grants available?

Yes there are grants available for homes built before 2006  in ROI via the Better Energy Homes Scheme, ranging from €2,250 for a midterrace house up to €4,500 for a detached house.

You can also avail of the Home Renovation Incentive which allows you to claim an income tax credit (maximum €4,050 over a period of four years). In NI the Affordable Warmth Grant Scheme offers a maximum grant of £10,000 for houses with solid wall construction but your gross annual income needs to be less than £20,000.

Can it be used on any type of house?

External wall insulation is most suitable for masonry walls that are of either solid construction or cavity wall construction. Not generally recommended for timber or steel frame walls or when the wall is clad with timber.

So which insulation should I use?

There are a number of different manufacturers of insulated panels and these generally come in the form of either expanded polystyrene slabs or mineral wool. In ROI the National Standards Authority of Ireland (NSAI) provides guidance in relation to the application of EWI along with a comprehensive a list of Irish Agrément Certified EWI products so choose from this list. The NSAI has a directory of approved installers that can provide a guarantee and warranty for the installation.

In NI the British Board of Agrément provides guidance in a similar manner to the NSAI and provides a current list of Agrément Certified products, manufacturers and installers registered in NI (and the UK).

How much insulation do I need?

This will depend on the wall construction, the type of insulated panel and associated finishes you chose, but in ROI, generally speaking approximately 160mm of insulation would be required to meet the requirements of Technical Guidance Document Part L 2011 for a new build wall.

The heat loss requirements for an existing wall are not as high, and approximately 100mm of insulation is generally required to achieve the necessary standard. In NI the Building Regulations requirements result in approximately 100mm of wall insulation for a new build and approximately 50mm for an existing wall.

Do I need to secure planning permission?

In many cases external wall insulation will be exempt from planning permission. In ROI, the exemption clause in Section 4 (1)(h) of the Planning and Development Act 2000 states: ‘constituted works which do not materially affect the external appearance of the structure so as to render the appearance inconsistent with the character of the structure or neighbouring structures’.

Despite the fact that a layer of external wall insulation has been applied to your home, the selection and application of external render may ensure that the external appearance of the house is not materially affected. The requirements in NI are similar. If you have doubts, it is advisable in ROI to apply to your relevant local authority for a Section 5 Declaration to confirm whether the work is considered exempted development or if it will require planning permission.