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What do I need to know about new foundations for an extension?

Foundations are required to carry and distribute the load of the building safely. Therefore, all buildings should have adequate foundations. The factors that need to be considered when designing a foundation are:

  • Type of soil
  • Adjacent structures
  • Trees
  • Drains and sewers
  • Size and construction of the new building
  • Ground condition
  • Landfill sites

It is advisable to contact a structural engineer or speak to a building control body about plans for new foundations. 

Read more about foundations for extensions

Common Questions

Do I need planning permission to convert my garage into a workshop?

If the garage will remain in domestic use - for example, as a personal hobby or home workshop - then planning permission is typically not required.  

However, it’s important to check whether there are any planning conditions, covenants, or restrictions attached to your property or the garage itself that may limit or prevent conversion.  

Read about planning permission for garage conversions on Planning Portal.  

Do I need building control to refurbish an existing dormer roof with insulation

Significant changes to insulation and thermal elements would normally require building regulations approval. The extent to which this applies depends on the existing insulation and what it will be replaced with.

If the work is completed by a member of a competent persons scheme, then an application for approval will not be required.

Find out more about insulation and building regulations on our common projects.

Is planning permission or building regulations approval required to change to an electric garage door?

Changing a standard garage door to an electric garage door will not normally require planning permission. Instead, they are covered by permitted development rights.

Permission may be required if your property is listed, you live in a conservation area or there will be a visual impact on the appearance of the house as viewed from the street. If you are unsure, it is advised that you contact your local planning authority.

Work to install an electric garage door must comply with Part P of the building regulations. This can be done by using an electrician who is registered with the competent person scheme.

Visit the website for registered electrical competent persons.

What documents to I need to make a planning application?

Your planning application must be made up of:

  • The necessary plans of the site
  • The required supporting documentation
  • The completed form
  • The correct fee.

The local planning authority will not be able to process your application unless the mandatory supporting documentation has been provided. You can also attach any other relevant documentation which you think will help the local authority determine the application.

What supporting documentation must be provided depends on the application type,  development type and local planning authority.

There are two levels of mandatory documents, national and local. If you’re applying online, the service will tell you what mandatory documentation you need to provide and allows you to attach the relevant documents. Most applications will require you to provide a location plan and a site plan.

In addition to the national list, your LPA may produce a list which details any specific documentation that is required to accompany the application. The requirements may vary according to the type of application, i.e. household, full, outline, etc. If you are applying online, this list is available from the supporting documents screen or your local planning authority’s website.

For more information around what to submit visit the how to apply section on Planning Portal.

Is there a maximum height for a new dormer?

Yes, under permitted development, a new dormer must not be higher than the existing highest part of the roof. It should also have materials that are in similar appearance to the existing roof. Additional limits apply in conservation areas and on listed buildings. Read about planning permission for loft conversions on Planning Portal

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