Smart lead times explained
One of the first questions we get asked about Smart aluminium windows and doors is how long they take. It is a fair question and it deserves a straight answer, but it is also a question that gets answered badly across the industry, because “lead time” means two completely different things depending on who is using the word.
A fabricator quoting a two-week lead time means two weeks from a signed order to a pallet leaving the factory. An installer quoting eight weeks means eight weeks from your first phone call to the last window being sealed. Both are honest. They are measuring different things. This guide explains what actually happens between order and installation, how long each stage takes, and what you can do to move it along.
Note: the figures below are drawn from published 2026 UK trade sources and reflect typical ranges across the Smart fabricator network. Because Smart supplies profiles to approved fabricators rather than building finished units itself, lead times vary between suppliers.
Standard lead times
Smart Systems is a systems house. It designs and extrudes the aluminium profiles and powder coats them at its site in Yatton, North Somerset, then supplies them to approved fabricators who cut, build and glaze the finished windows and doors. That structure is why you will see very different lead times quoted for what looks like the same product.
Here is what the published 2026 trade data shows across the network.
| Product and specification | Average factory lead time |
| Smart windows and doors, standard specification | 4 to 6 weeks |
| Aluminium windows and doors, stock colours | 2 to 3 weeks |
| Smart Alitherm 400 windows, black, white or anthracite grey | 2 weeks |
| Aluminium bifold doors, standard colours | 6 to 8 weeks |
| Any aluminium system, non-standard RAL colour | 6 to 10 weeks |
Two things to take from that table. First, the spread is enormous, from two weeks to ten, and almost all of it is explained by colour and product type rather than by the system itself. Second, every one of those figures is a factory lead time. None of them include the survey before the order or the fitting slot after delivery.
Arc Glazing works to 6 to 10 weeks end to end, covering survey, order, fabrication, delivery and installation, with standard specifications at the shorter end and bespoke work at the longer end. That is the number that matters if you are planning a build programme, because it is the one that tells you when you will have a finished opening.
Factors that affect delivery
Colour
This is the big one, and it catches almost everybody. Most fabricators hold stock in anthracite grey (RAL 7016), black (RAL 9005) and white (RAL 9010), which is why those three colours are always the fastest. Anything outside the stock range has to be powder coated to order, and that adds a separate stage with its own queue. Expect a non-standard RAL to add several weeks and 10 to 20% to the price.
Dual colour, different inside and out, adds more again, because the frame goes through the coating line twice.
Product type
Windows are quicker than doors. Doors are quicker than bifolds. A bifold has more profile, more hardware, more glass units and more fabrication hours than a casement window, and the published trade figures reflect that: 2 to 3 weeks for windows against 6 to 8 for bifolds at the same fabricator.
Glass specification
Standard argon-filled double glazing with a warm-edge spacer is held in volume and rarely holds anything up. Upgrades do:
– Triple glazing, heavier units, longer to source
– Acoustic glass, particularly asymmetric units, usually made to order
– Solar control coatings, specialist stock
– Toughened or laminated glass, required by Building Regulations in low-level glazing and next to doors, and generally quick, but it is another processing stage
None of these are dramatic on their own. Two or three combined on a large project can add a fortnight.
Site readiness
The most common delay on any glazing project is not the factory. It is the opening not being ready. We cannot survey a hole that has not been formed, and we will not manufacture off a drawing for an opening that does not yet exist, because a 10mm variance between drawing and reality means a remake and a remake costs far more time than it saves.
Time of year
The trade has a rhythm. Spring and early summer are the busiest period across the whole industry, and fitting diaries fill up first. If your project has flexibility, ordering in late autumn or winter usually buys you a shorter wait.
Installation scheduling
Understanding the sequence helps you plan around it. A typical Arc Glazing project runs like this.
1. Quote. We discuss the project, confirm the system, colour and glass specification, and price it. For straightforward replacements this can be done quickly. For extensions and new openings we usually want to see the drawings.
2. Survey. A physical site survey with exact measurements. This is the point at which the order becomes real. Nothing goes into manufacture before it, and the survey cannot happen until the structural opening exists, the lintel is in and the reveals are formed.
3. Order and manufacture. Final sizes go to the fabricator and the factory lead time starts. This is the stage the tables above are measuring.
4. Delivery. Units arrive and are checked before they go anywhere near your house. Damaged or incorrectly made units are spotted here, not on your driveway.
5. Installation. Removal of the existing frames, fitting, sealing, making good and clearing up. A straightforward window replacement is usually a day or two. A large bifold set with structural coordination takes longer.
6. Certification. Replacement windows and external doors are notifiable work under Building Regulations. As a registered installer we self-certify the work, so there is no separate building control application to wait on.
The stage most people underestimate is the gap between delivery and installation, because that is a diary question rather than a manufacturing one. Ask about it early.
Tips for faster delivery
If the timeline matters on your project, these are the levers that actually move it.
Choose a stock colour. Anthracite grey, black or white will get you to site weeks sooner than a special RAL. If you have your heart set on a heritage green, that is a legitimate choice, but make it with the timeline in front of you rather than after the order is placed.
Get the opening finished first. Push your builder to complete the structural work before the survey rather than in parallel with it. Every week the opening is not ready is a week the factory clock is not running.
Sign off sizes once. Changes after the order goes in restart the fabrication queue. Get the specification right at survey stage and hold it.
Order everything together. Windows and doors placed as a single order are usually built and delivered together. Splitting them across two orders can mean two lead times and two fitting visits.
Ask which lead time you are being quoted. If a quote says six weeks, ask whether that is six weeks to delivery or six weeks to a finished installation. The answer changes your build programme by a month.
Book the fitting slot when you order, not when the units land. Diaries fill from the front. Provisionally holding a slot at order stage costs nothing and can save a fortnight.
Do not rush the survey to save a week. An accurate survey is the single cheapest insurance on the whole project. Remakes are measured in weeks, not days.
Frequently Asked Questions
How long do Smart windows take to arrive?
Smart windows in a standard specification and a stock colour typically take 4 to 6 weeks from final specification to delivery, with some fabricators offering fast-track slots of two weeks on popular colours. A non-standard RAL colour extends that to around 6 to 10 weeks. Smart supplies profiles to approved fabricators rather than building finished units, so the exact figure depends on who is manufacturing your order.
Does choosing a special colour delay my order?
Yes, and it is usually the biggest single delay you can add. Most fabricators hold stock in anthracite grey, black and white only. Any other RAL has to be powder coated to order, which adds a separate production stage and typically pushes the lead time from 4 to 6 weeks out to 6 to 10 weeks, along with a 10 to 20% price increase.
Can you fit windows before the building work is finished?
We can survey once the structural opening is complete, the lintel is in and the reveals are formed, but not before. Manufacturing from drawings rather than a physical survey risks a size mismatch, and a remake takes longer than waiting for the opening did. Talk to us early so we can sequence the survey against your builder’s programme.
Do I need building control approval for replacement windows?
Replacement windows and external doors are notifiable work under Building Regulations. Because Arc Glazing is a registered installer, we self-certify the installation, so there is no separate building control application for you to submit or wait on.
Lead times move with the season and the specification, so the only reliable answer is a current one. Tell us what you are planning and we will confirm the specification, the manufacturing time and a realistic installation window, in writing.
[Check Lead Times and Get a Quote]
Related Guides
– [How Much Do Smart Windows Cost in the UK?]
– [Are Smart Windows Any Good?]
– [Smart heritage Windows]
– [Back to Smart Windows & Doors Hub]