Does External Wall Insulation Comply with Building Regulations?

There are approximately 7 million solid wall properties in the UK that could potentially have insulation added either externally or internally to upgrade the thermal performance and extend the longevity of the walls. The walls account for approximately 40% of the heat loss area in a typical property. By upgrading them, a typical family can save £100s off their heating bills whilst in the process enjoying a comfortable and cosy property.

What are the building control standards for external wall insulation?

According to the advice offered, where a solid wall is upgraded by the installation of insulation then it must meet the minimum energy efficiency values set out in the Approved Documents.

However, if such an upgrade is not technically or functionally feasible, the element should be upgraded to the best standard which can be achieved within a simple payback of no greater than 15 years.

Where 25 per cent or more of an external wall is being renovated, building regulations would normally apply, and the thermal insulation of the wall would have to meet the standards required by the Approved Documents. In this context renovation means the provision of a new layer or the replacement of an existing layer, but excludes decorative finishes.

How much insulation is sufficient to meet building regulations?

This will depend on the material you are using and the type of wall that you are applying the insulation to. For a typical 9-inch solid brick property, 90mm of EPS or 110mm of high density mineral wool brings the U-value down to 0.3, which is the current minimum for building regulations.

Of course, if you are installing the insulation on a cavity wall or an alternative type of wall (a timber frame or system build wall), then the required insulation level is going to vary. In this case, speak to your installer or a system designer to find the minimum insulation required, as it will vary greatly depending on the U-value of the current wall.

What is the reality of interpretation from some local authorities?

In our experience from talking to installers, local authorities tend to interpret the regulations differently from one to another. We always recommend checking with your local authority to confirm that your plans meet the regulations, and where appropriate, obtaining planning permission for the works.

What do I need to send a planning application for external wall insulation?

  • Drawings – These can be full-blown architects’ drawings or some simple scale drawings. Typically you would submit a location plan (showing the building and its surrounding properties), a top-down plan and elevation drawings of each elevation to be installed, with a ‘before and after’ showing the changes created by the works.
  • Material used – Technical documentation showing how the system is installed is the best option, as this will let the authorities see what is used and how they are applied.
  • BBA system certification – The materials used or system as a whole should have the correct accreditations, typically British Board of Agrement accreditation. This ensures that the system being installed is appropriate and will not create more problems for the building further down the line.
  • Evidence of the warranty that the works are going to have – If anything goes wrong with the materials or the install, it is important to know that they are put right, and if you are in a very sensitive area like a conservation area, the council are going to want to be reasonably happy that the works are covered.

What can I do if I am in a conservation area?

Conservation areas will nearly always require some sort of planning, but every conservation area is different. Some are relatively lax and will only be concerned if the insulation is going on the front of the building and will affect the view from the street. Others will be more strict and wherever the insulation goes on they will want to be completely assured that the resulting finish is appropriate for the area.