Get an Instant Estimate for Your House Extension

Use our simple Project Estimate Calculator to get a rough idea of your project costs. Just enter your requirements below for an instant estimate.

Extension estimator

Price your extension in about 60 seconds

Pick your extension type, slide the dimensions and choose your spec — we’ll show you a realistic ballpark based on the rates we actually build to. No forms to fill in first.

A rough idea only. Every project is different — this tool gives a genuine ballpark, not a quotation. Your accurate price comes after a proper survey.

What are you building?

Pick the closest match — you can tell us the detail later.

How big?

Slide to your rough overall dimensions — the plan and price update as you go.

Length 5 m

2 m14 m

Width 4 m

2 m10 m

inc. VAT · rough guide

Your footprint

Build your spec

The range covers low spec to high spec. Or start at low spec and tick the upgrades you’d want — we’ll tailor the figure.

Happy with the ballpark?

Send us your details, drawings and photos and we’ll come back with an accurate estimate. No drawings yet? No problem — we offer a full design & build service.

Your ballpark so far

Drawings & photos

Both optional — but the more we can see, the tighter the estimate.

Upload drawings (if you have them)

Architect plans, sketches, planning drawings — PDF, JPG or PNG

Upload photos of your property

The rear/side of the house, the garage, anywhere the work happens

No drawings yet? Ask about our design & build service — we handle drawings, planning and the build under one roof.

Any other works needed?

Tick anything that applies — we’ll include it in your accurate estimate.

Tell us more

Your details

We’ll only use these to talk to you about your project.

Name *

Please add your name

Phone *

Please add a contact number

Email *

Please add a valid email

Property address *

Please add the property address

Postcode

Anything else we should know?

By sending this you’re happy for Rosebrick Developments to contact you about your project. Nothing is binding — the ballpark above is a rough guide only.