Supply-only or supply-and-fit bifold doors: what is the cost difference?

The choice is less about the absolute price and more about who carries the risk of measuring, fitting and getting compliance right.

Cost breakdown of each route

The table compares indicative UK 2026 costs for a three-pane aluminium bifold bought supply-only against a supply-and-fit package, into an existing opening. The door set is similar in both, but the surrounding responsibilities differ.

With supply-only you pay for the door and then add a fitter's labour separately, plus you carry the risk of measuring correctly. With supply-and-fit, the installer surveys, supplies, fits and usually certifies the glazing, wrapping it all into one price. The totals can be close, but the risk profile is very different.

Indicative UK figures; supply-only totals depend on the fitter you hire separately.

When supply-only makes sense

Supply-only can be the lower-cost and more flexible choice in specific situations:

• You already have a builder on site for an extension, who can fit the doors as part of the wider job.
• You are confident measuring the opening accurately, since errors on a made-to-measure set are costly.
• You want to choose a specific door system and arrange independent fitting.

The risk is that responsibility for correct sizing, safe handling and compliance falls on you. A mismeasured opening can mean a remake at full cost, which wipes out the saving. Aluminium bifolds are also heavy and need careful handling on site, so the fitter you choose must be experienced with the specific system to avoid problems with folding and sealing.

When supply-and-fit is better value

Supply-and-fit puts one company in charge of surveying, manufacturing, fitting and certifying the doors. For most homeowners replacing patio or French doors, this is the lower-risk option. The installer measures the opening, so a sizing error is theirs to put right, and a registered fitter can self-certify the glazing for Building Regulations through a scheme such as FENSA, avoiding a separate building control fee.

A workmanship guarantee on top of the product warranty gives a single point of accountability if anything goes wrong, rather than the door supplier and fitter pointing at each other. The modest premium over arranging fitting yourself often buys reassurance that is hard to replicate with separate trades. For a one-off project where you do not have a builder on site, supply-and-fit usually represents the more dependable value even if the headline figure is slightly higher.

How to compare the two fairly

To compare honestly, build the full cost of the supply-only route, not just the door price. Add a realistic fitting labour figure, the cost of any specialist lifting or handling, and a contingency for measurement risk. Then set that total against the supply-and-fit quote, checking that both cover the same threshold, glazing and making good. Only then can you see the real difference.

Also weigh the non-cost factors. Supply-and-fit gives one accountable company, a workmanship guarantee and self-certified compliance. Supply-only gives flexibility and potential saving if your separate fitting is cheap and accurate. For confident project managers with a builder already engaged, supply-only can save money; for most homeowners, the single accountable quote of supply-and-fit is the simpler and safer choice, and the price gap is often smaller than it first appears.

It is also worth asking what each quote includes around the edges, because that is where hidden costs sit. A supply-and-fit price should state whether it covers removing and disposing of the old doors, the threshold type, any scaffolding, and making good the reveals and internal finish. A supply-only price covers the door alone, so you add all of those yourself, plus delivery and the handling of a heavy aluminium set. Lining the two up on the same scope, rather than comparing a bare door price against a complete installed job, is the only way to judge them fairly. When both are itemised on a like-for-like basis, the decision usually comes down to whether you value the saving and control of supply-only or the single accountable warranty of supply-and-fit.

Frequently asked questions

Sources & further reading

• Checkatrade — bifold door cost guide
• MyJobQuote — bifold door prices
• FENSA — replacement window and door rules

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.