How much will my dream home cost?

Architect Kelly O'Driscoll discusses...

David Green from Dorchester asks...
“I’ve bought a bungalow; how much is it going to cost to make it my dream home?”
Architect Kelly O’Driscoll of Western Design Architects answers this common question.
We hear this a lot, and unfortunately the answer is “it depends…” but what does it depend on? There are many factors to consider before even beginning to build.
Surveys: A measured building survey ensures your Architect’s drawings are as accurate as they can be, these can cost from £900 to upwards of £1500 depending on the scope of works.
Ecology surveys – a bat survey is often required when altering the roof of an existing building as they are a protected species.
The Architect will inform the client of any further surveys they feel would be necessary, such as asbestos, tree and ground investigation surveys.
Professional Fees: In addition to Architect fees, you will probably require a Structural Engineer and maybe an Energy Consultant. If your site or proposal is controversial we may advise a Planning Consultant to assist with the planning process. You may want a Landscape Designer and to be really sure of costs from an early stage, a Quantity Surveyor.
The Design: Are you wanting to alter internally, extend up or out into the garden – all these have different costs and depend entirely on the building & location. In some circumstances it is cheaper for a whole new extension, in others an attic conversion is the way forward. Here is where your Architect’s expertise will arrive at the best design solution for you.  
Statutory Fees: Assuming this is for your own home, the cost of a Local Authority planning application fee is generally £172 (£385 for a new build home). You will then require construction drawings for your builder to construct your dream home. These will need to be approved by Building Control, who charge a separate fee and this varies per home and location.
Build costs: These will typically range from between £1200/sqm through to beyond £2500/sqm, and will depend whether you intend on doing any work yourself, the quality of the materials & finishes and how long you intend for the build to take – there will inevitably be a compromise between time, quality and cost.  These costs do not incorporate a contingency which we would always advise, especially alterations to an existing building, of at least 10%.
Figures often exclude VAT which is applicable on extensions but not new build work so if you are considering major works it may work out cheaper to demolish and build from new.