How Long Does It Take to Build an Extension in East Devon?

Typical build times for common extension types

For the construction phase alone, assuming drawings are approved and the site is clear, these are the ranges we work to in practice. Weather, ground conditions and the level of finish you choose can move things either way, so treat them as a guide rather than a promise.

A build is not finished when the roof goes on. Second fix, plastering, decorating and floor finishes typically account for the final third of the programme, and it is this last stretch that most people underestimate.

• Small single storey rear extension (up to about 20 square metres): 8 to 12 weeks
• Larger single storey or wraparound extension (30 to 50 square metres): 12 to 18 weeks
• Double storey side or rear extension: 16 to 24 weeks
• Extension combined with a knock through and full kitchen refit: add 3 to 6 weeks on top

The part nobody budgets time for: planning and design

Before any work starts you need drawings, and in many cases planning consent. East Devon District Council aims to decide householder applications within 8 weeks, but validation, neighbour consultation and any requests for amendments can stretch this to 10 to 14 weeks. Much of Budleigh Salterton sits within a conservation area and close to the coast, so materials and roof forms attract closer scrutiny than they might elsewhere.

Some single storey extensions fall under permitted development, which avoids a full application. You will still want a lawful development certificate for peace of mind and for when you sell, and that takes a further 6 to 8 weeks. Building regulations drawings, structural calculations and a party wall notice to neighbours, where one applies, run alongside this and need to be sorted before the builder can price the job properly.

Realistically, allow 4 to 6 months from first conversation with a designer to being ready to start on site. Starting the paperwork in the autumn is a sensible way to be building by spring.

What slows an extension down once you are on site

Ground conditions are the biggest unknown locally. Parts of East Devon sit on clay, and tree roots or drains near the footings can mean deeper excavations than the drawings assumed. A building control inspector will look at the trench before concrete goes in, and if they ask for more depth that is a day or two lost plus extra muck away.

Steel beams and bespoke glazing are the other common culprits. Structural steel usually has a 2 to 3 week lead time once the fabricator has final dimensions, and large sliding or bifold doors can be 6 to 10 weeks from order. A good builder will order these well before they are needed, but any late change to the opening size starts the clock again.

• Wet winters delaying groundworks and brickwork on exposed coastal sites
• Late decisions on kitchens, tiles or sanitaryware holding up second fix
• Discovering old drains, soakaways or unrecorded services under the garden
• Waiting on utility companies to move a gas meter or electricity supply

How to keep your extension on programme

The single most useful thing you can do is make your decisions early. Have the kitchen designed, the flooring chosen and the door supplier confirmed before the footings are dug. Every choice made in advance is one less pause waiting for a delivery or a price.

Ask your builder for a written programme with the main stages dated, and agree how changes will be handled. A weekly ten minute walk round the site with whoever is running the job catches small issues before they become a week's delay. Finally, be realistic about living arrangements. A rear extension that opens into the kitchen usually means a few weeks without a working kitchen, and planning for that up front makes the whole process far less stressful.