What actually drives the cost of an extension, and why a price per square metre only tells you part of the story.
Why there isn't one number
Two extensions of identical size can differ substantially in price. The variables are ground conditions, drainage, the amount of structural work needed to open up the existing house, the glazing specification and the standard of internal finish. A cost per square metre is a starting point for a conversation, not a quotation.
What tends to move the price
Foundations are the first unknown — trees, drains and made ground can all mean deeper or wider foundations than expected. Structural steel to remove the existing rear wall is the second. Large spans of glazing and high-specification kitchens are usually the largest single line items after the shell.
How we price it
We visit the property, look at access, drainage and the existing structure, then price against a written scope so you can see what is and isn't included. If something can only be confirmed once the ground is open, we say so rather than burying it in a provisional sum.
Talk it through with us
Every property is different. If you would like this applied to your own project, send us the details and we will give you a straight answer.
Start a project enquiry