Guide
How much does a house extension cost in Hertfordshire?
The honest answer is: it depends on your house and what you want. This guide explains what drives the price, what to budget for beyond the build itself, and how to get a figure you can rely on.
Typical costs
[Geoff: 3 to 4 typical price bands, e.g. small single-storey rear extension, kitchen extension, larger or two-storey extension. Real figures from his recent jobs.]
Every home is different, so these are guide figures only. The only way to get an accurate price is a visit and a written quote, which we give for free.
What affects the price of an extension
- Size and shape. Bigger costs more overall, but the cost per square metre often falls as size goes up.
- Glazing. Bifold doors, sliding doors and rooflights are among the biggest single items.
- Ground and drainage. Poor ground, trees nearby or drains in the way can mean deeper or specialist foundations.
- Kitchen and bathroom fit-out. A new kitchen or en suite can be a large share of the total.
- Finishes. Flooring, underfloor heating, lighting and decoration.
- Access. Terraced houses with no side access take longer to build.
Costs on top of the build
- Drawings, and structural engineer calculations
- Planning or prior approval fees, if needed
- Building control fees
- Party wall agreements, if you build on or near a shared wall
- VAT: check whether a quote includes it
Does an extension add value?
Usually, yes, particularly a bigger kitchen and family space or an extra bedroom. How much depends on your street and the ceiling price for houses like yours, so speak to a local estate agent before you decide how far to go.
Getting an accurate quote
We visit, measure up and talk through what you want, then give you a written, itemised quote. See how we work or ask for a free quote.
Related: house extensions · kitchen extensions · planning permission
Common questions
How much would an extension cost in the UK?
Prices vary a lot around the country. In Hertfordshire, our extensions typically cost [Geoff: range]. Use the factors on this page to see where your project might sit, then ask us for a free quote.
How much does a kitchen extension cost?
Allow for the building work plus the kitchen itself. Ours typically cost [Geoff: range]. See kitchen extensions.
How much is a two-storey extension?
A two-storey extension costs more overall but often less per square metre, because the foundations and roof serve two floors. Ours typically cost [Geoff: range, or remove if he doesn’t build two-storey].