Planning Permission For Timber Frame Extensions

Knowing whether you need planning permission for timber frame extensions can be confusing and off-putting for many homeowners. With the increasingly competitive nature of the housing market and seemingly endlessly increasing property prices, extending an existing property makes sound financial sense.

Before starting a new building project, it is vital to understand how planning permission and building regulations may apply to your build. Although the two terms are often used together, they govern two very different elements of construction.

Applications for planning permission and timber frame building regulations approval are considered under different laws. Since they are separate pieces of legislation, approval for one doesn’t confer approval for the other.

The Development Management Team of Local Planning Authorities is given power by the government to handle planning permission applications. This is used to control the way towns and cities develop through the use and appearance of buildings and land.

Highways access, environmental impact, landscaping and conservation are also considered. Building regulations are a set of standards governing all construction work in the UK. They are used to ensure the safety of occupants living or working in the building and its immediate surroundings. To clarify this, we will address some of the most frequently asked questions regarding planning permission for bespoke oak structures.

1. Do you need planning permission for timber framed extensions?

The use of timber as a construction material in itself does not affect the need for planning permission. All timber used for oak framed buildings will have the load-bearing capacity and fire resistance required by law for construction.

Since dimensions, use and location are the main factors considered for planning permission, the material itself is not usually an issue. However, there is one exception to this.

Any materials used in exterior work must have a similar appearance to the existing house, with the exception of conservatories. For example, if an exposed frame is part of the extension design, this should match the existing look of the house.

2. What size extension can I build without planning permission?

The proposed ground area covered by your extension will affect whether you will need to apply for planning permission. No more than half of the total area of the property (excluding the original house) should be occupied by extensions or other buildings.

Therefore, if you have freestanding structures on your property it will affect the size of the extension you can build without planning permission. No part of the extension should extend beyond a wall facing a road if it is a principal or side elevation.

Regardless of placement, no extension should be wider than half the width of the original house. For detached dwellings, no single-storey rear extension should extend further than four metres from the wall.

For all other types of houses, this is reduced to three metres. Rear extensions of more than one storey should not extend further than three metres.

3. How big can I make my extension?

In addition to the ground area, the height of your extension should also be considered if you wish to avoid a planning permission application. Without planning permission, side extensions can only be one storey high and no more than four metres in height.

Within two metres of the property boundary, the eaves must be no higher than three metres. No part of an extension should be higher than the highest point of the roof of the original building.

In addition, the pitch of the extension roof should match the pitch of the existing roof as much as practically possible. In areas of outstanding natural beauty, national parks, world heritage sites and conservation areas, no extension can exceed one storey.

In these areas, no part of the extension should extend beyond an adjoining principle or side elevation.

4. How close to my boundary can I build an extension?

Known as the ‘boundary of the curtilage’, this is the edge of the enclosed space around the original house. For example, a wall hedge or fence surrounding the house and dividing it from other properties is the boundary.

It is worth noting that this is not a legal definition and the Local Planning Authority may define the legal boundary differently. It is always worth clarifying this with them to avoid accidentally building without the appropriate permission.

Side extensions on detached homes should be at least one metre away from the side boundary. For all types of houses, single-storey extensions should be no closer than 3.5 metres to a boundary with a road to the rear.

For extensions of more than one storey, no part should be within seven metres of a boundary to the rear of the house.

5. Can you double the size of your house with an extension?

While this is physically possible, it will be impossible without planning permission. The rules cited above outline what is known as ‘permitted development’ for extensions without planning permission.

Doubling the size of your house would far exceed these rights and a planning application would need to be made. However, this could still be approved by the local council if your building plans fulfil their criteria.

6. What happens if you build without planning permission in the UK?

Even if your extension plans fall within permitted development, it is possible that details will have to be changed during construction. This can cause what is known as a planning breach and whether deliberate or not can have serious repercussions.

As the homeowner is ultimately responsible for any planning breach, you will be held personally accountable. It is possible to submit a retrospective application and if this is successful, no harm is done.

If it fails, the council can issue enforcement demanding alterations or possibly demolition. Committing a planning breach is not in itself a criminal act, but ignoring an enforcement notice is.

If you fail to comply, you can be prosecuted and fined. If demolition is required and you do not carry out the work yourself, the council is entitled to perform the work itself.

You will then be billed for the cost of work and incur further fines if this is not paid. Failing to plan properly and obtain permission where needed can be an extremely costly mistake.

If you are unsure, visit for guides and advice on planning permission.

Hardwoods Group offers a wide range of pre-designed oak frames suitable for extensions, garages, oak-framed porches and more. These can be supplied as ready-to-build kits for ease of construction with the minimum fuss. We also offer a bespoke design service for individual designs machined to your exact specifications. For further information, contact us, and we will be happy to help.