A common question that I’m asked when someone is thinking about a kitchen extension is how long it’s all going to take. Usually this inquiry is followed by whether it will be finished for Christmas.
The honest answer is that a kitchen extension nearly always takes longer than people expect, but when it’s planned properly, the timescales are far more predictable than their reputation suggests.
What catches people out is that the physical building work is only part of the story. By the time a builder turns up, most of the important decisions should already have been made, with orders placed and approvals sorted. Miss this preparation work and the build will struggle to get off the ground whilst everyone waits for drawings, approvals and materials. Get the preparation right, and the whole process feels much more under control, even when construction starts and the inevitable disruption kicks in.
Phase one: Before you start your kitchen extension
Before a single brick can be laid, there’s a surprisingly long runway called the pre-start phase. This phase is often underestimated, partly because it doesn’t feel like “doing the build”, but it’s also the part that has the biggest influence on how smoothly the build phase will run.
1. Concept work (at least 2 weeks)
The very first step is usually a short burst of concept work. This might be as simple as sketching ideas over the kitchen table, pulling together inspiration and having some honest conversations about budget and priorities.
In many cases this takes a couple of weeks, not because the work itself is slow, but because decisions need to be made which often need to be slept on. Rushing this stage often leads to expensive changes later, particularly when people haven’t fully thought through how the new kitchen design will work when it’s finished.
2. Designing a kitchen extension (two to four weeks)
Once the concept is agreed, the design then needs to be finalised. Whether you’re working with an architect, a designer or a design-and-build contractor, this stage is about turning ideas into a technical design that can be priced, and then built out.
Layouts are fixed, structural openings agreed, glazing sized and kitchen layout ideas finalised. At the same time, choices around cabinetry, worktops and appliances need to be made. Allow two to four weeks here if decisions can be made promptly, but be aware that indecision can easily stretch this out.
3. Ordering materials and booking trades (at least eight weeks)
The longest wait in the entire process often comes next – ordering materials and booking trades. Bespoke kitchen cabinetry, high end kitchen appliances and specialist glazing can have lead times of eight to ten weeks, and sometimes even longer.
Good kitchen fitters, electricians and plumbers are also booked well in advance, particularly in busy areas or ahead of peak seasons. This is where even well planned projects can stall if orders weren’t placed early enough.
4. Permissions and regulations (at least eight weeks)
Planning permission and building control sit alongside all of this. Some kitchen extensions fall under permitted development, others don’t, and structural changes always need building control approval regardless.
Even where planning isn’t required, structural calculations, drainage proposals and insulation details all need to be set out and agreed. Local authority timescales vary, and whilst building control is usually pragmatic, they won’t rush because a homeowner has booked a kitchen delivery.
In terms of how long planning permission takes, expect to factor in at least eight weeks.
Phase two: Building your kitchen extension
Once everything is in place, the building work for your kitchen extension ideas can begin. The early days are usually the messiest, as demolition and site clearance get underway. Existing doors, windows or walls come out, and as the site is prepared the garden often looks worse for wear.
This part can be quick, and sometimes just a few days. But it’s also the stage where neighbours tend to notice what’s going on, so good communication helps.
1. Your kitchen extension's foundations and drainage (at least two weeks)
Extension foundations and drainage are next, which is where ground conditions start to influence the timeline. Straightforward trench foundations can be dug and poured within a week, but unexpected drainage diversions, poor ground conditions or deeper foundations can slow things down.
This is also a key point where inspections are required. Concrete can’t be poured until the excavations have been inspected. If your inspector is busy, this can mean a short pause before concreting can proceed.
The actual pouring of concrete can take around a week, but factor in at least a week of delays.
2. Building your kitchen extension's walls and roof (at least four weeks)
Once the foundations are poured, the superstructure progresses quickly. Medium sized brick and block builds might take a couple of weeks to get up to wall plate level, while faster build systems such as timber frame or SIPs can shorten this significantly.
Roof construction and roof coverings follow, and getting the extension watertight is a key milestone. This should take another couple of weeks and until watertight has been achieved, progress inside should be on hold to avoid damage from the weather.
3. First fix electrical and plumbing work (from two days to six weeks)
With the shell complete, attention turns to making good and first fix operations. Openings are formed, and new windows and doors go in. Electricians and plumbers also get started by running their cables and pipework before the walls are closed up.
The time this stage takes varies hugely depending on the specification and complexity of the build. It could be as quick as two days for a basic kitchen extension but if the kitchen layout is ambitious, or includes kitchen islands, bifolds, underfloor heating or lots of integrated appliances, extra time is needed, potentially up to six weeks. Don’t forget, first fixing is a key inspection stage so you'll also need to call in the building control inspector.
4. Plastering and screed (at least two weeks)
Plastering and screeding marks the end of the first fix phase, and is the moment where patience pays off. Freshly poured floors and new plaster needs time to dry, especially in cooler months, or where underfloor heating isn’t yet operational.
Rushing ahead with paint or tiling can lead to problems, so take your time. A few extra days here will avoid remedial work later. This will take at least two weeks, depending on the size of your kitchen extension, as well as if it is a open plan kitchen extension or separated off into different rooms.
Phase three: Fitting out your kitchen extension
Once the structure is complete and reasonably dry, the focus shifts to the kitchen itself. This is an exciting stage, but one where sequencing becomes critical.
Before any new kitchens units can be fitted, the room must be properly prepared. Floors levelled, walls checked, and plumbing and electrical services installed to suit the kitchen design. This prep work only takes a day or two, but if something's not quite right, skipping it will become a false economy.
1. Fitting your kitchen units (at least two days)
Kitchen fitting is often quicker than people expect. A competent installer with everything on site can usually install base and wall units in two or three days.
Problems tend to arise not from the fitting itself, but from missing components or last-minute changes. Checking deliveries and not changing your mind is therefore vital to keep things on track.
2. Fitting new kitchen worktops (at least ten days)
Kitchen worktops introduce a built-in pause. Solid stone and quartz worktops can only be templated once the base units are fixed in place. Templating is usually quick, but fabrication can take ten days or so, and sometimes longer during busy periods.
This is normal and needs to be factored into the overall programme. If laminate worktops are specified, these can be installed straight after the cabinetry, so the timeline here is much quicker.
3. Second fix kitchen electrics and plumbing (two days to two weeks)
Once the worktops are installed, the second fix phase can continue. Appliances installed and connected, sinks and taps plumbed in, electrics completed and tested, and any remaining tiling finished.
This stage can take anywhere from a few days to a couple of weeks, depending on how available the trades are. Building control will also want to make their final inspection, so book this in and let everyone know when it’s happening.
4. Decorating your kitchen extension
The final touches are what turns a building site into a beautiful living space. Decorating, kitchen flooring and snagging all happen here, and whilst these jobs are individually small, they still need time to complete. Trying to rush to meet an arbitrary deadline often results in poor quality so don’t do it – patience is advised.
When to start
If there’s one piece of advice that I give quite often, it's to work backwards from when you want the kitchen finished, not when you want builders to start. For anyone hoping to be cooking Christmas dinner in a new kitchen, an August or early September start on site is usually the sweet spot. Add in the pre-start phase, and for the average kitchen extension the likely project timeline is going to take around six months to complete. This might mean that the summer holidays have to go on hold whilst the pre-start phase is done properly.
Trying to squeeze a kitchen extension into a tighter window is possible, but it relies on everything going right, from design sign-offs to planning approvals and supplier lead times. In my experience, the projects that feel less stressful are those that are well planned, with breathing space built in, and trades who are lined up well in advance.
With a bit of good planning, the whole build will be better organised so trades can get their work done quickly. By starting early, even the jeopardy of a Christmas deadline won’t become a regrettable experience.
Making sure you properly budget your kitchen extension costs will ensure your kitchen extension timeline stays on track and doesn't cause any delays. Underestimating whether you have enough funds is a common kitchen design mistake, so avoiding this by ensuring you don't overstretch yourself is important.
