Beyond the BlueprintVisit Website →
← Back to blog

UK Kitchen Extension Timeline: Why Planning Can Take 8 Weeks

October 15, 2026
UK Kitchen Extension Timeline: Why Planning Can Take 8 Weeks

Most UK kitchen extensions take 6 to 12 months from your first architect meeting to Building Control sign-off, with on-site construction making up 12 to 20 weeks of that total. Planning and approvals eat the most time, not the building work itself, so the single biggest lever you have is sorting statutory checks and long-lead items during the design stage, before anyone picks up a trowel.

TL;DR:

  • Planning decisions normally take 8 weeks from validation, or 13 for complex cases; full plans building regulations usually take 5 weeks.
  • Check sewer locations, ground conditions, and party wall requirements during design; late discoveries can force redesigns, new consents, or weeks of delay.
  • Confirm written lead times for bespoke cabinetry, glazing, and specialist joinery before signing; delay delivery until the structure is watertight to prevent moisture damage.
  • Add 10% to 20% contingency to approvals and 10% to 15% to construction, and tie staged payments to completed milestones rather than upfront fees.
Extensionkings
Plan Your Kitchen Extension With Confidence
Extension Kings designs and builds bespoke extensions across the West Midlands, managing planning and building regulations from consultation to handover.
Explore extension services

Table of Contents

At-a-glance kitchen extension timeline

Here is a rough breakdown of how the months add up for a typical kitchen extension:

  • Design and surveys: 3 to 6 weeks for drawings, revisions and sign-off.
  • Planning permission (if required): 8 weeks normally, or 13 weeks for unusually large or complex cases from a validated application.
  • Building regulations: around 5 weeks for a full plans submission, occasionally up to 8.
  • Pre-construction: 2 to 8 weeks to finalise contracts, insurance and deliveries.
  • On-site build: typically 12 to 20 weeks, depending on scale.
  • Snagging and completion: 1 to 6 weeks for final fixes and certificates.

Add it together and most households are looking at 6 to 12 months end to end, though a straightforward permitted development project can land at the shorter end while anything needing full planning, structural engineering or a party wall agreement tends to sit nearer the top. Some projects run longer still, usually because approvals or deliveries stack up rather than because the build itself drags.

Phase 1: design, surveys and appointing your team

Before anyone applies for permission or orders a brick, you need drawings that reflect what you actually want, and that takes longer than most homeowners expect. Architectural drawings and a measured survey commonly take a few weeks on their own, and that is before revisions and your own sign-off, which can add more time if you change your mind on layout or glazing.

Where the extension affects load-bearing walls or needs a steel beam, structural engineering input has to happen alongside the architectural drawings, not after them, so the two processes should run in parallel rather than one after the other.

A few survey items are worth ordering as soon as you start, rather than waiting until planning is submitted:

  • Drainage and sewer checks: knowing whether you are building over or near a public sewer early avoids redesigning the extension later.
  • Site levels and ground conditions: these feed directly into foundation design and cost.
  • Party wall survey: if you share a boundary wall, start this conversation now rather than at planning submission.

Finding a builder and getting proper itemised quotes also takes time once you factor in site visits and back-and-forth on specification. It pays to run this alongside your planning and building regs applications so your contractor is confirmed by the time approvals land rather than afterwards.

Pro Tip: Confirm lead times for your kitchen units, bespoke joinery and any large glazing at the design stage, not once the quote is signed, since some of these items take longer to arrive than the build itself.

Approvals: planning, building regs, party wall and sewer consents

This is where most kitchen extension timelines actually stretch, because these are fixed statutory windows rather than something your builder can speed up.

Planning permission, where required, has a standard decision period of 8 weeks from validation, extending to 13 weeks for larger or more complex applications. If your local authority does not decide within the relevant period, check the official guidance on appealing for non-determination. A pre-application check may help identify issues before submission.

Building regulations approval follows a separate track. A full plans application typically gets a decision within 5 weeks, with some authorities taking up to 2 months by agreement. A building notice lets you start work two days after submission, but you forgo the pre-approval check and carry more inspection risk if something needs correcting later.

Planning and building approval timeframes compared

The Party Wall Act is separate from planning and building regulations, and it catches people out because it is easy to forget until a neighbour raises it. Check the official Party Wall Act guidance and allow time to serve notices before works begin.

Sewer and build-over consents vary by water company. Many respond within 14 days where a simple protocol agreement applies, but formal applications, CCTV surveys or design amendments can add weeks.

Key statutory windows to remember:

  • Planning permission: 8 weeks normally, or 13 weeks for unusually large or complex cases.
  • Building regulations full plans: usually 5 weeks, or by agreement up to 2 months.
  • Party wall notices: allow time before works start and check the official guidance.

Pre-construction: site set-up and ordering long-lead items

Once approvals are in hand, there is still a short runway before your contractor breaks ground. This stage usually covers finalising the build programme, confirming site insurance, arranging temporary works such as scaffolding or protection, and agreeing a delivery schedule with your main contractor.

Certain items have longer lead times than homeowners expect, and ordering them late is one of the most common causes of a stalled build:

  • Bespoke kitchen units: order as soon as the design is locked, especially for made-to-measure cabinetry.
  • Large glazing and sliding doors: these are often the longest lead item on the whole project.
  • Specialist joinery: anything custom-built should be confirmed alongside your contract signing.

Hold off on delivering fitted units and finished glazing until the structure is watertight. Boxed items left on an open site risk moisture damage during wet trades, and most suppliers only give a narrow window to report transit damage.

Pro Tip: Notify your utility company about any meter relocation at the design stage, since moving a gas or electricity meter can itself take several weeks to schedule.

Construction on site: a week-by-week view

Once the diggers arrive, the sequence is fairly consistent across most single-storey kitchen extensions, even though exact durations shift with ground conditions and scale.

  1. Weeks 1 to 2: groundwork and foundations. Excavation, drainage runs and oversite preparation, longer on clay or waterlogged ground.
  2. Weeks 3 to 6: superstructure. Blockwork walls, lintels and roof structure go up, with the aim of getting the building watertight as soon as possible.
  3. Weeks 6 to 8: first fix. Electricians and plumbers run cables and pipework through the new structure, and structural carpentry for the roof or any internal openings is completed.
  4. Weeks 8 to 11: plastering and drying out. Walls and ceilings are plastered and left to dry before any finishing work begins.
  5. Weeks 11 to 14: second fix and kitchen fitting. Sockets, switches, flooring and kitchen units go in. Kitchen fitting within a larger extension commonly takes around two months once you include design tweaks and supplier coordination.
  6. Weeks 14 to 16: snagging and final inspections. Small defects are corrected and Building Control carries out the final inspection before issuing a completion certificate.

A standard single-storey kitchen extension typically takes around 14 weeks on site, though double-storey and wrap-around projects can run longer because there is more structure to build and more trades working in sequence rather than in parallel. A double-storey addition often adds several extra weeks for the upper floor structure and roof tie-in, while a wrap-around extension can extend the groundworks and superstructure phases because of the larger footprint.

Booking Building Control's final inspection in advance, rather than waiting until the work is finished, is one of the simplest ways to avoid a gap between finishing on site and getting your completion certificate.

Common causes of delay and how to reduce them

A handful of issues cause delays on kitchen extension projects, and many can be avoided with earlier planning rather than faster building.

  • Incomplete planning applications: missing information triggers requests for further detail, which resets the clock. A pre-application check with your local authority catches this before submission.
  • Party wall disagreements: a neighbour who disputes the notice, or simply does not respond, can stall your start date by weeks. Serving notices early and agreeing a surveyor in advance keeps this moving.
  • Sewer issues found late: discovering a public sewer under your proposed footprint after design is finalised means redrawing plans and reapplying for consent. A sewer location check at survey stage avoids this entirely.
  • Supply and trade bottlenecks: kitchen units, glazing and specialist fitters often have their own waiting lists, and poor coordination between suppliers and fitters is a recurring complaint among homeowners.
  • Weather and site access: groundworks in winter, or a build on a tight urban plot with limited access, both add time that a summer project on an open site would not face.

Pro Tip: Ask your kitchen fitter directly about their current waiting list before you commit to a delivery date, since installer availability is one of the most common reasons kitchen fitting slips past its planned week.

Time budgets and contingency: how much extra to plan for

Even a well-managed project benefits from a buffer, because statutory timescales and supplier deliveries are largely outside your control. We suggest adding 10 to 20% time contingency to your approvals stage and 10 to 15% to the on-site build, alongside the 10 to 15% cost contingency most budgeting guidance recommends.

Staging payments against completed milestones, rather than a flat upfront fee, protects you if a phase slips and gives you leverage to hold back the final payment until snagging is genuinely finished.

Three things worth locking down before you sign a build contract:

  • Confirm who is responsible for chasing planning and building regs decisions.
  • Get written lead times for every long-lead item before the contract is signed.
  • Make sure the contract states who manages sewer and party wall consents.

How we manage timelines on West Midlands projects

Running design, planning, building regs and the build itself through one coordinated team removes most of the handover gaps that cause delays elsewhere. We manage planning, check sewer locations before drawings are finalised, and build milestone payments around the stages that actually determine your completion date. If you want a realistic timescale for your own project, a site survey gives us what we need to put real weeks against each phase.

How Extension Kings helps reduce timeline risk

Coordinating design, approvals and build under one team removes the handover delays that happen when separate architects, planners and builders are not talking to each other. We set a realistic budget and timeline before the site survey, then keep payments tied to milestones so you always know where the project stands.

Extensionkings

  • One team, start to finish: design, planning, building regs and construction managed together.
  • Realistic budgeting upfront: cost guidance before any site survey takes place.
  • Local West Midlands knowledge: regional cost detail available in our extension cost guide.

Get in touch to book a site survey and find out what your own timeline looks like.

FAQ

How long does a kitchen extension take in the UK?

Most UK kitchen extensions take 6 to 12 months from first appointing an architect to Building Control sign-off. On-site construction itself usually accounts for 12 to 20 weeks of that total, with the rest spent on design, planning and approvals.

What is the 3 metre rule for extensions?

If you plan to build over, or within 3 metres of, a public sewer or lateral drain, you need to check for water company consent before building. Confirming sewer locations at the design stage avoids costly redesigns or delays once construction has started.

What is the 7 year rule for planning permission?

This question usually confuses two separate rules: the 4-year rule for unauthorised building work and the 10-year rule for unauthorised change of use, both of which can make a development immune from enforcement in England once the relevant period has passed. There is no official 7-year rule, so it is worth checking the current position with your local authority or the Planning Portal rather than relying on the figure.

Is £30,000 enough for a kitchen extension?

Whether your budget is enough depends heavily on size, specification and whether structural work such as steel beams is needed, so it is not possible to give a single answer without those details. We recommend getting at least three itemised quotes and setting aside a contingency on top of the build cost before fixing a budget.

Sources