How long does a house extension take? A realistic timeline
Knowing how long your extension will take is just as important as knowing what it will cost, especially if you are living in the property while the work goes on. In this guide we set out a realistic timeline for a house extension, from the very first drawings through to handover, and explain what can speed a project up or slow it down. Every project is different, but these ranges reflect typical, well run builds in Solihull and the West Midlands.
Before work starts on site
The part many people underestimate is the design and approvals stage, which happens well before a single brick is laid. This includes measured surveys, architectural drawings, structural engineer calculations and, where needed, a planning application. Drawings and structural design typically take a few weeks. If a planning application is required, you should allow roughly eight weeks for a decision, sometimes longer. If your project is permitted development, you can move much more quickly. Our guide on planning permission explains which route is likely to apply to you.
The build, stage by stage
Once work begins on site, an extension follows a natural sequence. Each stage depends on the one before it, which is why a build cannot simply be rushed. A typical order of work looks like this:
- Groundworks and foundations. Setting out, digging and pouring the foundations, and getting up to floor level.
- Structure. Building the walls, installing any steel beams, and constructing the roof.
- Making watertight. Fitting the roof covering, windows and external doors so the space is weatherproof.
- First fix. Running electrics, plumbing and any heating pipework before the walls are closed up.
- Plastering and second fix. Plastering the walls and ceilings, then fitting sockets, switches, radiators and internal doors.
- Finishing. Kitchen or bathroom installation, flooring, decoration and the final details, followed by a clean and handover.
How long each type takes
As a general rule, a single storey extension takes around eight to twelve weeks on site, while a double storey extension takes around twelve to twenty weeks because there is more structure and finishing involved. Larger or more complex projects, such as a wrap around extension with extensive glazing, naturally take longer. If you are choosing between the two, our comparison of single and double storey extensions covers the trade offs. It is also worth remembering that the finishing stage, which includes decoration and the fitting of kitchens or bathrooms, often takes longer than people expect, so it is wise not to plan any major event around a tight completion date.
What can affect the timeline
Several things can influence how long a project takes. Weather can hold up groundworks and roofing. Ground conditions that are worse than expected can add time at the foundation stage. The availability of specific materials or bespoke items such as windows can be a factor, so ordering these early helps. Perhaps the biggest variable of all is decision making. Delays in choosing finishes, tiles, kitchens or bathrooms can hold up the finishing stage, so making these decisions early keeps everything moving.
Living in your home during the build
Many homeowners stay in their property while a single storey extension is built, and with good planning this is perfectly manageable. The new extension is usually built alongside the existing house and only connected to it near the end, when the old external wall is opened up. This means the disruptive, dusty phase of breaking through is often relatively short. During the build you should expect some noise during working hours, deliveries and skips outside, and a period without your kitchen if that is the room being extended. A considerate builder will seal off the work area, keep the site tidy, and agree sensible working hours with you. For larger double storey projects, or where the only kitchen or bathroom is affected, some families choose to move out for part of the build. We will always give you an honest view of what to expect so you can plan around it.
How we keep your project on track
A well organised builder makes an enormous difference to the timeline. We plan the programme carefully so that trades follow on smoothly and the site is never standing idle, and we keep you informed at each stage so you always know what is happening and what is coming next. This is one of the things clients mention most often in the reviews on our case studies page. If you would like a realistic timeline for your own project, get in touch and we will talk it through, and you can read our advice on choosing a builder before you commit.
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