The short answer
A straightforward replacement typically takes one to two days to fit, once the doors arrive on site. Swapping an existing patio or French door for bifolds in the same opening is the quickest case — often completed in a single day for a smaller set, or two days for a wide unit or where finishing and making good is involved. The bigger variable is what happens before installation day: bifold doors are made to measure, so there is usually a lead time of several weeks between ordering and delivery while the doors are manufactured. Jobs that need a new or enlarged opening, a steel beam or lintel, or structural alterations take significantly longer overall — often a week or more on site — because the building work and inspections come first.
The fitting itself is usually quick, but the total project time depends heavily on whether structural work is involved and on the manufacturing lead time. Here is what to expect at each stage.
Timescales at a glance
- Like-for-like swap1-2 days on site
- Wide / multi-panel setOften 2 days
- New opening + steelA week or more
- Manufacturing lead timeTypically several weeks
- Survey to fittingAllow weeks, not days
The fitting itself: usually one to two days
For the common scenario — replacing an existing door or window with bifolds in the same opening — the physical installation is quick. A competent two-person team can often remove the old unit, prepare the opening, fit and level the new frame, hang and adjust the panels, seal and weatherproof, and make good in a single day. A wider set with several panels, or a job that needs more careful making good of plaster, flooring and external finishes, more typically runs to two days.
The reason it is so fast is that bifold doors arrive as a pre-engineered system, manufactured to the exact measurements taken at survey. The frame, track, panels, glass and hardware are designed to go together, so on-site time is about accurate fitting and levelling rather than fabrication. Getting the frame perfectly square and level is the critical part — bifolds are precision products, and a frame that is even slightly out can cause the panels to bind or fail to fold smoothly. A good installer spends time on this rather than rushing, which is why two days is sensible to allow even when one day is achievable.
Jobs that take longer: structural work
The picture changes substantially when the project involves more than a like-for-like swap:
- Forming a new opening: if you are knocking through a solid wall to create a wider aperture, the wall has to be opened up, temporarily supported, and a new structural beam installed before the doors go in. This is several days of building work in its own right.
- Installing a steel beam or lintel: widening an opening usually requires a steel beam (RSJ) or engineered lintel sized by a structural engineer. The steel must be fitted, the load transferred, and the work inspected by building control before the opening is finished.
- Removing a load-bearing wall: the most involved case, needing engineer's calculations, temporary propping, the new beam, and inspections.
In these scenarios the doors are one of the last things to go in. Realistically you should plan for a week or more on site, and the project needs proper sequencing of the structural trades.
The lead time before fitting day
For most homeowners, the longest part of the process is not the fitting at all — it is the wait between ordering and installation. Because bifold doors are made to measure, the supplier needs a precise survey, then time to manufacture the bespoke set. From the day you confirm the order, a lead time of several weeks is normal while the doors are built, with busy periods, premium finishes or non-standard sizes potentially extending it.
The typical sequence is: initial quotation and design, a detailed technical survey to take exact measurements, the order placed into manufacture, the lead-time wait, then delivery and installation. It is worth confirming the quoted lead time in writing and not booking a trade to finish flooring or decorating until the doors are confirmed delivered, since dates can slip. Planning around the manufacturing window — rather than assuming a quick turnaround — is the single most useful thing you can do to keep the project on track. The fitting may be a day or two, but the realistic end-to-end timeline from decision to finished doors is usually measured in weeks.
A realistic end-to-end timeline
Pulling the stages together gives a clearer picture than the fitting time alone. For a typical homeowner replacing existing doors with bifolds, the journey runs roughly like this. First comes the quotation and design stage, where you agree the configuration, finish and threshold. Then a technical survey takes the precise measurements the doors will be manufactured to — this is a separate, more detailed visit than the initial sales measure, and it is critical to getting a set that fits.
Once the order is confirmed into manufacture, the lead time begins — usually several weeks while the bespoke set is built, longer for premium finishes or non-standard sizes. When the doors are delivered, installation follows: one to two days for a like-for-like swap, or a week or more where structural work and inspections are involved. After fitting there may be a short period of making good and finishing — plastering the reveals, touching up paint, laying or reinstating flooring up to the threshold — which is sometimes done by other trades on their own timeline.
So while the headline "how long to fit" answer is one to two days, the realistic end-to-end timeline from deciding on bifolds to standing back with finished doors is more often several weeks to a couple of months, dominated by the manufacturing lead time. Planning around that — confirming lead times in writing, not booking finishing trades until delivery is certain, and allowing some slack for slipped dates — is the single most useful thing you can do to keep the project smooth and avoid the frustration of a half-finished opening waiting on doors that have not yet arrived.
Two extra factors can stretch the timeline and are worth allowing for. Access matters: doors that must be carried through the house, up steps, or into an awkward space take longer to handle than those that go straight in from a driveway. And making good after a structural opening — plastering, flooring and external finishes — may run on after the doors are in, sometimes involving separate trades. Building a little contingency into your plans for these covers the common reasons a job runs slightly beyond the headline estimate.
Frequently asked questions
How long does it take to install bifold doors in an existing opening?
For a like-for-like replacement in the same opening, fitting is often completed in one day, or two days for a wide multi-panel set or where significant making good is needed. The doors arrive pre-made, so on-site time is mostly about fitting the frame square and level and weatherproofing.
Why is there a wait before my bifold doors can be fitted?
Bifold doors are made to measure, so after the survey the supplier manufactures your set to exact dimensions. This lead time is typically several weeks. The wait is for manufacturing, not the fitting itself, which is quick once the doors arrive on site.
How much longer does a new opening take compared with a replacement?
Considerably. A like-for-like swap is one to two days, but forming a new or wider opening with a steel beam adds several days of structural work, temporary support, and building control inspection before the doors go in. Allow a week or more on site for that kind of project.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific opening and material. They are guidance, not a quotation.