How Much Does a Single Storey Extension Cost in Worcestershire?

Typical price ranges per square metre

Builders usually price extensions per square metre of internal floor area. In Worcestershire, a realistic guide for the build itself is roughly £1,900 to £2,800 per square metre for a good standard finish, rising to £3,000 or more for a high specification with large areas of glazing. These figures normally exclude VAT, which is 20% on most extension work, and exclude a fitted kitchen.

As a rough guide to what that means in practice:

• Small rear extension, around 15 square metres: roughly £30,000 to £45,000
• Medium kitchen diner extension, around 25 square metres: roughly £48,000 to £70,000
• Large wraparound or full width extension, around 40 square metres: roughly £75,000 to £115,000

What pushes the cost up or down

Two extensions of the same size can differ by tens of thousands of pounds. Smaller extensions also cost more per square metre, because the fixed costs of foundations, scaffolding and setting up the site are spread over less floor area.

Ground conditions matter more here than many people expect. Much of the county sits on clay, which can mean deeper foundations, particularly near mature trees. Properties close to the Severn, Teme or Avon may need flood resilient design, and sloping plots around the Malvern Hills often need retaining walls or stepped foundations.

• Structural openings: knocking through the back of the house needs steel beams, typically £2,500 to £6,000 fitted depending on the span
• Glazing: bifold or sliding doors commonly cost £4,000 to £10,000, and roof lanterns £1,500 to £4,000
• Roof type: a flat roof is usually cheaper than a pitched and tiled one
• Drains: moving a manhole or building over a shared sewer adds cost and needs approval from Severn Trent
• Access: terraced streets in areas such as St John's or Barbourne can mean materials carried through the house, which adds labour
• Matching materials: reclaimed brick or stone to suit an older property costs more than standard facing brick

The costs people forget to budget for

The builder's quote is only part of the total. Professional fees and the internal fit out often add 10% to 20% on top, so it helps to list them before you settle on a size.

A kitchen is the biggest of these. If the extension is for a new kitchen diner, allow anything from £8,000 for a decent mid range kitchen to £25,000 or more with stone worktops and integrated appliances.

• Architectural drawings and building regulations plans: roughly £1,500 to £4,000
• Structural engineer's calculations: roughly £400 to £1,200
• Planning or lawful development application fees, where needed: a few hundred pounds
• Building control fees: typically £600 to £1,200
• Party wall surveyor, if you are building on or near a boundary: often £1,000 or more per neighbour
• Flooring, decorating, heating alterations and making good the garden or patio

Planning permission in Worcestershire

Many single storey rear extensions fall under permitted development, which means no full planning application. As a broad rule, that covers up to 3 metres out from the original rear wall on a semi detached or terraced house and 4 metres on a detached one, subject to height limits and other conditions.

Those rights are restricted or removed in conservation areas, for listed buildings and within the Malvern Hills and Cotswolds National Landscapes, which take in places such as Great Malvern and Broadway. Your local planning authority will be Worcester City, Wychavon, Malvern Hills, Wyre Forest, Bromsgrove or Redditch, and it is worth checking with them early. Building regulations approval is needed in every case, whether or not planning permission is.

How to get a quote you can rely on

Ballpark figures are only useful for deciding whether the project is feasible. For a price you can hold a builder to, get drawings done first and ask each builder to quote against the same set, so you are comparing like with like.

Ask for a written, itemised quote that states clearly what is excluded, whether VAT is included and how payments are staged. Keep a contingency of around 10% for anything discovered once the ground is opened up, such as poor soil or an uncharted drain.