Cost Estimator
An early, order-of-magnitude construction cost range for extending, refurbishing or building a new home.
Knowing roughly what a project might cost is one of the most useful things to have at the very start. This estimator is built from our own benchmark rates on comparable Cotswolds and Gloucestershire projects. It isn't a quote or a cost plan, but it's the kind of figure worth having before you commission drawings or speak to a contractor.
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Describe your project
Choose the type of work, its size and the level of finish you have in mind.
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See a realistic range
The range updates as you go, with a breakdown of where the money goes.
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Talk it through with us
Send us your range and we'll give you an honest view on what's achievable.
Estimate your project
What are you planning?
How big is it?
A single-storey kitchen extension is often 15–30 m². A full-width two-storey addition is often 40–90 m².
A three-bedroom house is often 90–120 m². A larger family home is often 180–250 m².
What level of finish?
Anything else to account for?
More roof and foundation for each square metre of floor
Excavation, retaining walls and waterproofing
Supply and fit, scaled to your finish level
Supply and fit, per room
Extra care, materials and consents typically add to cost
Local labour and material costs vary significantly
How to read this
Millar Howard Workshop are Chartered Architects, not Quantity Surveyors. This range is calculated from benchmark construction rates on comparable residential projects, adjusted for size, specification, region and the factors above.
It is early-stage guidance, not a cost plan or quotation. Actual costs depend on ground conditions, structural findings, contractor pricing at the time of tender, and decisions made through design. We recommend a Quantity Surveyor’s cost plan once a scheme is developed, and always before committing to a budget.
What usually moves the figure
The ground and the structure
Foundations, drainage, retaining walls and what’s found when the existing house is opened up are the most common causes of change.
Glazing and openings
Large sliding doors, rooflights and steelwork to open up walls bring light and views, and are often the biggest single choices in a budget.
Decisions made through design
Materials, joinery, heating and renewables can all be tuned. Early, honest conversations about cost keep the design and the budget aligned.
Ready to talk about your project? We’d love to hear from you.
An estimate is only a starting point. Get in touch
and we can talk through what’s realistic for you.