Two extra storeys no longer require full planning. Make the most of this opportunity.

Extending homes by two storeys will no longer require full planning permission. Are you ready to help customers wanting to take advantage of this easing? The new rights to build two extra storeys on an existing property will come into force on 31st August 2020 in England only. The government has said the new rules are in being put in place to make it easier for homeowners to build more bedrooms for a growing family or for elderly relatives to have their own self-contained flat, for instance.

The changes will be allowed under Permitted Development. This restricts the powers of local councils to prevent development going ahead.

Fightback Tip: Publicise the new rules on your website and social media.
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While homeowners are going to be happy with the news, it hasn’t been well received by councils and architects. But the government has made it clear that anyone wanting to build upwards will have to carefully consider the impact on neighbours and the appearance of the extension.

This isn’t the end of the reforms. The government is expected to lay out even more significant changes to the planning system in a policy paper later on in July.

Below are the key details of the government’s Town and Country Planning Explanatory memorandum relating to development of an existing home. You can read the full document here.

Permitted Development right to extend existing homes by two extra storeys

So existing houses which are detached, semi-detached or in a terrace can be extended upwards by two extra storeys to provide additional living space by constructing additional storeys.

Detached house

The right allows the construction of up to 2 additional storeys on the topmost storey of 2 storeys or more.

It also allows 1 additional storey on a detached house of 1 storey, above ground level.

Terraced house or semi-detached house

The ruling allows the construction of up to 2 additional storeys on the topmost storey of a house of 2 storeys or more.

It also allows 1 additional storey on a house of 1 storey above ground level.

Roof space

Existing accommodation in the roof space of the existing house, including a loft extension, is not considered as a storey for the purposes of this right.

The right allows engineering operations necessary for the construction of the additional storeys.

Height and overlooking

The right is subject to a maximum height limit for the newly extended house of 18 metres. Where the house is in a terrace its height cannot be more than 3.5 metres higher than the next tallest house in the terrace.

To prevent overlooking, a window cannot be installed in a wall or roof slope of a side elevation of an additional storey built under this right. As with existing permitted development rights to extend or alter houses the external appearance of the materials used in the construction of the additional storeys must be of similar appearance to that of the existing house.


The right applies to houses built since 1 July 1948 (being those granted planning title under the current planning system) and 28 October 2018 when the proposal to introduce a permitted development right to extend existing houses upwards was first announced.

Prior approval

The right to build two extra storeys is subject to obtaining prior approval from the local planning authority. They will consider certain matters relating to the proposed construction of additional storeys. These considerations include the impact on the amenity of neighbouring premises, including overlooking, privacy and overshadowing; the design, including the architectural features of the principal elevation of the house, and of any side elevation which fronts a highway; and the impacts a taller building may have on air traffic and defence assets and on protected vistas in London.


The local planning authority is required to make a decision on an application for prior approval under the right within 8 weeks. The right does not provide a default deemed consent if the local planning authority fails to make a decision within this time, reflecting the significance of the matters under consideration including the potential impacts of the proposed development on the amenity of neighbours and on air and defence safety. If a decision has not been made within 8 weeks there is a right of appeal to the Secretary of State for non-determination of the prior approval application.

What next? How can you benefit?

With our PlansXpress software you can help customers show what the extension will look like. Drop the plans into EstimatorXpress and you can give them an almost instant estimate. So act quickly to capitalise on this opportunity – your competitors will! Now is the time to put everything into the ‘fight back’ and these types of changes in legislation can really help.

Book an online demonstration with one of the team, or start a free trial. Give us a call on 0117 916 7898 or go online to get ready for these new opportunities.