What a Single Storey Extension Costs in Suffolk in 2026

Typical price ranges in Suffolk

Builders usually price by the square metre of new floor area. In Suffolk in 2026, a realistic figure for the build itself is around £2,200 to £3,300 per square metre plus VAT, depending on specification. That covers foundations, walls, roof, windows, plastering, electrics and basic heating, but not a fitted kitchen, flooring or decoration.

Smaller extensions cost more per square metre than larger ones, because the fixed costs (digging out, scaffolding, knocking through, a steel beam) are spread over less floor.

• Small rear extension, about 15 square metres: roughly £38,000 to £55,000
• Mid-sized kitchen diner, about 25 square metres: roughly £55,000 to £80,000
• Large or wraparound, about 40 square metres: roughly £85,000 to £125,000
• Add 20% VAT to all of the above unless your builder has already included it

What pushes the price up or down

Ground conditions are the big local variable. Much of mid Suffolk sits on heavy boulder clay, which shrinks and swells with the seasons. If there are mature trees nearby, building control may ask for foundations 1.5 to 2.5 metres deep rather than the usual metre, and that can add several thousand pounds. The sandier soils east of Ipswich towards Kesgrave and Woodbridge are generally kinder.

Drainage is the other common surprise. If a shared sewer runs under your garden, you will need a build over agreement from Anglian Water, and sometimes a manhole has to be moved.

After that, it comes down to choices. A flat roof with a single rooflight is cheaper than a pitched, tiled roof with a vaulted ceiling. A three metre set of bi-fold or sliding doors can cost £4,000 to £9,000 on its own. Access counts too: a mid-terrace in central Ipswich, where everything has to come through the house, takes longer than a detached home with a side drive.

The costs that sit outside the builder's quote

A build quote rarely covers everything. Budget separately for the items below, and ask every builder to state clearly what is and is not included so you can compare like with like.

We would also suggest holding back a contingency of around 10%. Older Suffolk houses, particularly Victorian terraces and timber-framed cottages, often reveal something once the walls are opened up.

• Drawings and building regulations plans: roughly £1,500 to £4,000
• Structural engineer's calculations: roughly £500 to £1,500
• Planning application fee, if needed: a little over £500
• Building control fees: roughly £600 to £1,200
• Party wall surveyor, if you build near a boundary: often £1,000 or more per neighbour
• Kitchen, flooring and decoration: anything from £10,000 to £40,000 depending on taste

Planning and permissions locally

Many rear extensions fall under permitted development, which means no planning application. Broadly, that allows up to three metres out from the back of a semi-detached or terraced house and four metres from a detached one, within height limits. Larger schemes can sometimes go through a prior approval process instead.

Those rights are restricted or removed in conservation areas, of which Suffolk has many, including parts of Ipswich, Woodbridge, Hadleigh and Lavenham. Listed buildings always need consent, and homes within the Suffolk and Essex Coast and Heaths or Dedham Vale protected landscapes face tighter rules. Your local planning authority (Ipswich Borough, East Suffolk, Babergh and Mid Suffolk, or West Suffolk) can confirm what applies, and it is worth checking before paying for full drawings.

Building regulations approval is needed in every case, whatever the planning position.