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Double Storey Extensions

CK Architectural Manchester offers double storey house extensions across the whole of the Greater Manchester area, ranging from places like Manchester and Bolton right through to Rochdale and Stockport.

Double or two storey extensions as they are also popularly known are an incredible way to maximise your home space for a much lower cost than other renovations, and can really make a huge difference to the life you can have without having to move home.

We’re here to help you with every step of your build, from initial designs and consultations all the way through to project management and bringing your build to life with our expertise and years of experience ensuring the utmost efficiency and minimal costs.

For more information how we can help you create your perfect home, contact us today and speak with our architectural experts who can give you everything you need, all for free with no commitment required.

Are you ready to makeover your space?

Double storey house extensions
Street view of double storey extension
Rear view of double storey extension

The Benefits of a Double Storey Extension

A double storey extension designed by a good architect or architectural designer adds space to the ground and first floor of your house to the rear or to the side of your home. This alone has a huge list of benefits such as paying the same in equipment and site costs as you would for a single extension saving money in that respect, as well as getting a complete new addition to home.


The ground floor can have all the benefits of a single storey extension has to offer, like a bigger kitchen and/or utility room, or a feature room with the wow factor you’ve dreamed of, but with even more to offer too. The first floor then adds more of the essentials that can completely change your living situation like bedrooms, bathrooms, studies, or en-suites that can really increase the value of your home and improve quality of life.

Design considerations

Because of the size and shapes of these incredible, large and visible two storey extensions, it’s essential to take lots into consideration when looking at the architectural design. The additional spaces will be the same on both floors and the regulations are stricter than a single storey extension, specifically about fire escape and structure.

Making the first-floor bedroom bigger, for example, might create unneeded space on the ground floor, and the roof must harmonise well. Bedrooms need to have light, ventilation and means of escape. With two stories the planning limitations require that size and scale fit with its environment. Consider what you want to gain from the build, what you are willing to sacrifice and what your budget is.

We will perform a thorough walk over survey before we advise you on the next steps.  At the onsite survey, we will be looking at issues such as shared boundaries, party walls, sewers, is it a listed building or are you in a conservation area.

Design options

With something as intricate and practical as a double extension, it’s also important to make sure that time is taken to really understand the options at hand that you have available and the impact they will have on the build as well as the rooms when in use.

To put this into context, once you know the room sizes required, you need to plan how to access and ventilate them. Then, you need to make the external of the new building work well with the existing house. There are limitations in the planning guide for two storey extensions as they have more impact on their surroundings.

In addition to this, we also need to think about the appearance and style of the double extension too. We like to work with and enhance existing areas where possible as this means less new building, cost and impact to you. A double side extension needs to look subservient to the house. Typically, this is achieved by pulling the front wall back. Gaining a good balance is important. If the need for an additional bedroom is the prime motivator, you need to consider how best to use the additional space on the ground floor.

Double rear extensions must consider the overshadowing and loss of amenity or outlook from the neighbours near the boundary.

Planning Permission

Double storey extensions generally need planning permission, unlike most single storey extensions that have permitted development rights. There are many things to consider before submitting a planning application. Planners want to know how it impacts the street scene, does it enhance character, does it have a negative effect on the neighbours, does it affect light/privacy/amenity?

Our design consultants will advise how to achieve your requirements with the best opportunity of securing planning approval. We prepare and submit the application on your behalf, then act as your agent, talking directly with the council throughout the application.

See our full planning guide for everything you need to know before designing.

Double storey extension street view
Garden view of double storey house side extension
Side angle of double storey house extension

Building regulations

You will most certainly need a building certificate from a building control body – which is either the local authority or a private building inspector – for a double storey extension. We advise gaining the planning permission before paying for the detailed building regulations drawings.

Our detailed building regulations plans and specification drawings will include any necessary detail such as structure, passage of sound, disabled access (if needed), drainage, resistance to moisture, collision, impact, heat loss, ventilation, light, emergency escape and much more.

Our specification demonstrates the new double extension can and will be built in accordance with the building regulations approved documents above all else. These will then be submitted for a full plan check, amended if necessary, and once approved, they will be the standard that is built to and inspected against.

You can use these drawings for gaining quotations from builders.

Given the additional complexity of the building regulations for a two-storey extension, it is essential that your get the plans approved prior to commencing

Building and Builders

When choosing your builder, ensure that you choose someone with lots of specific and relevant experience and most importantly, choose someone you’ll feel comfortable working with and talking to about concerns – they are going to be in your life and home for a substantial amount of time. Be clear about your timescale expectations and specific finishes.

Quotations should be clear and easy to read with reference to our detailed approved building regulations drawings. Ask who will be doing the work, will it be their company, or will they be sub-contracting and who is managing the process. Make sure you discuss payment dates and check their payment structure and be comfortable with it. Don’t always go with the references they give you, it’s not hard to find out where else they may have been working.

We try to add as much construction details as possible, but some assumptions must be made, and certain areas investigated with the builder before moving forward. Ensure that you are happy with everything before proceeding. We offer help throughout for both you and the builder, and we will come to site if help is required.

Remember when you finally do come to build, only half of the building work will be outside.  You should plan and phase exclusion zones with your builder.

Living room inside single storey extension
Inside double storey extension
Bathroom of double storey extension

Are you ready to makeover your space?

Try our new

Online Design Service

  • Free property assessment
  • Free project feasability report
  • Design your project with our experts
  • Easy self survey guide
  • Online planning applications
  • Online building regulations drawings