Single Storey Extension

Building a single storey extension is the perfect way to create extra living space in your home, while transforming your space to better suit your lifestyle. More practical additions can be added or incorporated with re configured layouts such as utilities, studies and toilets.

single storey extension Design, planning and building regulations in North Yorkshire
single storey extension Design, planning and building regulations in North Yorkshire
single storey extension Design, planning and building regulations in North Yorkshire


Before beginning a project there are certain things to consider every design needs to be around what you want to achieve, how best to get it, limitations of planning and building regs and any potential complication of the build and of course the build cost. Site checks should be carried out on shared boundaries, partywall, mains sewers and is it a listed building or in a conservation area. To help us give you the best options we will go into detail of why you want to build then how to do it. It is advisable to give us a rough budget to design to, the last thing we want is to produce a design you love but can’t afford.


First the size, how does it integrate with the existing living spaces. 

Ventilation access what we don’t want is to design new spaces that are detrimental to existing space. You may have space already there that needs tweaking that can be altered and re-configured.

You don’t want to end up with dark unusable or impractical spaces or corridor effect.
Once the layout has been determined around the practical uses and layout has been established (tv, sofa, sink etc) then we can look at external doors, lights, roofing etc

Other important things to consider are drainage, roof style, trees, boundaries, access, external impact etc..

single storey extension Design, planning and building regulations in North Yorkshire
single storey extension Design, planning and building regulations in North Yorkshire

In most cases a single storey can be done under permitted development (see below) which means it does not need a home owner planning permission application.

Larger rear single storey extensions over the permitted development measurements can be done on a prior approval application. This is a basically a planning app that’s deemed approved. The council will send notice to any neighbours that share a boundary and if no reasonable objections its deemed approved.

If you do need planning permission there will be an 8 week period where all documents are submitted.Here at CK Architectural design consultants will advise what type of application is need and likelihood of approval. We will check the design against the planning guidance such as over development, impact on street scene, right of light, over shadowing, loss of amenity and outlook, massing/dominance, loss of privacy, etc.


An extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

No more than half the area of land around the “original house”* would be covered by additions or other buildings.

No extension forward of the principal elevation or side elevation fronting a highway.

No extension to be higher than the highest part of the roof.

Single-storey rear extension must not extend beyond the rear wall of the original house* by more than three metres if an attached house or by four metres if a detached house.

In addition, outside Article 2(3) designated land* and Sites of Special Scientific Interest the limit is increased to 6m if an attached house and 8m if a detached house until 30 May 2019.

These increased limits (between 3m and 6m and between 4m and 8m respectively) are subject to the prior notification of the proposal to the Local Planning Authority and the implementation of a neighbour consultation scheme. If objections are received, the proposal might not be allowed.

Maximum height of a single-storey rear extension of four metres.

Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres.

Maximum eaves height of an extension within two metres of the boundary of three metres.

Maximum eaves and ridge height of extension no higher than existing house.

Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house.

Two storey extensions no closer than seven metres to rear boundary.

Roof pitch of extensions higher than one storey to match existing house.

Materials to be similar in appearance to the existing house.

No verandas, balconies or raised platforms.

Upper-floor, side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor.

On designated land* no permitted development for rear extensions of more than one storey.

On designated land no cladding of the exterior.

On designated land no side extensions.

single storey extension Design, planning and building regulations in Scarborough


Most alterations to your home will require a building certificate from a building control body, either local authority or private building inspector. Once the design and planning has been approved you will then need a detailed set of drawings and specification that demonstrates the new extension can and will be built in accordance with the building regulations approved documents. These building regulations drawings will then be submitted for a full plans check, amended if necessary and once approved they will be the standard that is built to and inspection against. Our plans will include all the necessary detail such as structure, passage of sound, disabled access, drainage, resistance to moisture, collision, impact, heat loss, ventilation, light, emergency escape and much more. These drawings will used when the building control officer inspects the build to ensure the builder is carrying out the works correctly.


Once you have your detailed drawing approved it is time to get some prices we can recommend you builders we trust. We advise that any quotation you consider will be written up clearly and well detailed. Both you and your builder need to know exactly what is included in the price or disagreements will occur at the messy end of the project. We have extensive on site knowledge and work closely so we will always advise where we think areas need exploring or issues may arise. We advise that you use our drawings in line with the quotation and any additional information we don’t provide such as plumbing and electrics is agreed in detail before the first fix goes in. it will be costly changing thing once the initial preparation has been built. We offer help throughout for both you and the builder, we will come to site if help is required.

single rear extension Design, planning and building regulations in Scarborough