If you fit aluminium windows and doors for a living, your supplier decides more of your week than almost anything else. They set how soon you can book a job, whether the frames arrive on the day you've told the customer, how much glass your team has to lift, and how much margin is left once the job is done. Picking one on price per frame alone tends to cost more later.
This guide is for window and door installers, builders, main contractors, garden room companies and glazing firms who are choosing a trade supplier, or wondering whether to change. We manufacture Cortizo aluminium doors and windows in Leeds and supply trade customers across the UK mainland, so the guide covers the questions trade buyers ask us before they open an account.
The short version
- Find out who actually makes the frames. A fabricator cuts, assembles and glazes the product; a distributor or reseller buys it in, and each step between you and the factory adds cost and time.
- Ask for the lead time in working days and whether the delivery date is fixed when you order. Most UK aluminium fabricators quote 3–6 weeks.
- Unglazed supply is usually quicker and easier to handle on site. Glazed supply saves a step but makes the panels heavier.
- A good trade account should be quick to open, come with a clear price list, and give you one named contact.
- Check the system's tested classes, the guarantee terms and the coating standard, and visit the factory if you can.
What does buying aluminium windows and doors "at trade" mean?
Buying at trade means buying as a business that fits or builds, on an account, at prices set for repeat orders rather than one-off retail purchases. In practice it usually comes with:
- a price list you can quote from, rather than a separate quotation for every job
- prices that reflect the volume you order
- faster ordering by phone, email or messaging once your details are on file
- products supplied in the form that suits a fitter, such as unglazed frames you glaze on site
- delivery to your yard, the site or straight to your customer
Trade pricing is only half of it. The other half is how reliably the supplier turns an order into frames on the right day. A cheap frame that arrives a week late costs you a rebooked fitting team and an unhappy customer.
Fabricator, distributor or reseller: who are you buying from?
Aluminium windows and doors pass through up to four kinds of business before they reach site. Knowing which one you're dealing with tells you who controls the lead time and the quality.
System companies
A system company designs and extrudes the aluminium profiles, develops the hardware and has the system tested. Cortizo, Schüco, Smart Systems, AluK and Reynaers are all system companies. They sell profile to fabricators; for the most part they don't sell finished doors to installers.
Fabricators
A fabricator buys profile from a system company and makes the finished product: cutting, machining, assembling, fitting hardware, glazing where specified and checking each unit before dispatch. The fabricator controls the build quality and most of the lead time.
Distributors and resellers
A distributor or reseller buys finished units from a fabricator and sells them on. Some add useful local stock or a showroom. But they don't control the factory schedule, so their lead time is the fabricator's lead time plus their own handling, and their price includes their margin.
| Who you buy from | Controls the build? | Controls the lead time? | What to ask |
|---|---|---|---|
| Fabricator | Yes | Mostly; also depends on profile, glass and coating supply | Which system, which accreditation, and can I see the factory? |
| Distributor | No | Partly; adds its own handling time | Who makes the product, and how long does it sit with you? |
| Reseller or agent | No | No | Who makes it, who delivers it, and who do I call if something's wrong? |
None of these is wrong in itself, but you should know which you're paying for. If a supplier won't tell you who makes their frames, treat that as an answer.
Why do lead times and fixed delivery dates matter so much?
For an installer, lead time sets how soon you can turn a signed quote into a fitted job and an invoice. For a builder, it decides whether an opening sits boarded up waiting for doors while the rest of the programme stalls.
Most UK aluminium fabricators quote 3–6 weeks. Because we cut, assemble, glaze and deliver in-house, our standard lead times are:
| Order | Typical lead time |
|---|---|
| Unglazed, stock colour | 2–5 working days |
| Glazed, stock colour | 6–10 working days |
| RAL colours | Around 2 weeks |
| Woodgrain finishes | 4–6 weeks |
| Heritage doors | 3–4 weeks |
| COR Vision sliding doors | 4–6 weeks |
| Roof lanterns and flat skylights | Around 3 weeks |
Stock-colour lead times depend on order quantity, so ask for the date on each order rather than assuming it.
Estimated vs fixed delivery dates
A short quoted lead time is only useful if the delivery date holds. Ask every supplier two questions:
- Is the date fixed when I order, or confirmed later? An "estimated week" can move, and you often find out when it's too late to rebook your fitting team.
- Who delivers? When frames go through a pallet network or courier, they change hands at least once, and each handover is a chance for delay or damage.
We give a delivery date when you order, and it doesn't change. Deliveries go on our own branded vehicles with our own drivers, with no pallet networks or courier handoffs. That's what lets you book your fitting team against the date with confidence.
What changes a lead time
Colour and glass are the two biggest factors. Our seven stock colours carry the fastest lead times: White, Agate Grey, Anthracite Grey, Black, and three dual-colour finishes (Agate Grey on White, Grey on White and Black on White). Any other RAL colour is available but adds around two weeks, and woodgrain takes 4–6 weeks. Glazed orders take longer than unglazed ones because the glass units have to be made and fitted first. If a job is urgent, a stock colour supplied unglazed is the quickest route.
Should you order glazed or unglazed?
Most of our products can be supplied either way, and many trade customers mix the two depending on the job.
Unglazed supply
Unglazed frames come fully assembled with hardware and locking fitted, ready for you to glaze on site. Trade customers choose them because:
- they're the fastest option: 2–5 working days in a stock colour
- empty frames are far lighter to carry, lift and position, which matters when a glazed bifold panel can weigh up to 120kg
- you can source your own glass, or specify toughened, laminated, self-cleaning or acoustic units for a particular job
- the glass isn't exposed to damage while the frame is being fixed
Glazed supply
Glazed products arrive ready to fit, so there's one less trade and one less delivery to co-ordinate. That suits smaller teams, jobs without a glazier on hand, and projects where time on site matters more than time in the factory. Glazed stock-colour orders typically take 6–10 working days.
Glass thickness
If you glaze on site, match the glass to the frame. We specify glass thickness against the frame area of each unit:
| Frame area | Glass thickness |
|---|---|
| 2.5m² or less | 4mm |
| 2.6–4.5m² | 6mm |
| 4.6–5.5m² | 8mm |
| 5.6m² or more | 10mm |
Whichever route you take, agree before you order who is responsible for the glass specification, including safety glass where it's needed, so nothing falls between supplier, glazier and installer.
What should a trade account give you?
Opening an account shouldn't take longer than the job you want to quote. Look for:
- A quick set-up. If you need to submit references and wait weeks, the supplier isn't set up for small and growing firms.
- No minimum order. Some months you'll order a single door. You shouldn't be penalised for it.
- A price list you can quote from. You need to price jobs without waiting on a quotation for each one.
- Volume pricing. Your prices should improve as your orders grow.
- One named contact. A dedicated account manager who knows your jobs saves explaining each order twice.
- Easy ordering. Phone and email as a minimum; many fitters also want to send sizes and photos from site by WhatsApp.
- The full range on one account. Being able to order bifolds, sliders, windows, front doors and roof lanterns from one supplier means one delivery and one invoice.
Our trade accounts have no minimum order value and no lengthy application. We set accounts up the same day and send a bespoke trade price list within hours. Pricing is volume-based, you get a dedicated trade account manager, and you can order by phone, email or WhatsApp. All eight of our product categories are available at trade pricing.
How do trade prices for aluminium windows and doors work?
Trade prices are normally set per customer on a price list rather than published, because they depend on your volume and the mix of products you buy. A few things to watch when you compare suppliers:
- The middleman. Each business between you and the factory needs its margin. Buying direct from the fabricator removes that layer: there's no distributor markup because there's no distributor.
- What's included. Check whether each price includes glass, cills, add-ons, delivery and VAT. A low frame price with extras added later isn't a low price.
- Colour and glass. RAL, woodgrain and higher-specification glass all change the price as well as the lead time.
- Like for like. Compare the same system, size, glass and hardware. A cheaper door on a different system may not have the same tested classes or guarantee.
We operate a like-for-like price match on comparable quotations. Send the quote you want compared to sales@mazuli.co.uk.
What should you check before choosing a supplier?
The system and its test results
Ask which system the products are made from and for its tested classes, then compare them like for like. As an example, the Cortizo Bifold system achieves air permeability Class 4 (EN 12207), water tightness Class 9A (EN 12208) and wind resistance Class A3 (EN 12210), from a 2,700mm × 2,530mm three-panel test sample. A supplier who can't give you their system's results can't tell you how the product will perform on an exposed site.
Security
Find out what locking comes as standard and what's available as an upgrade. On our bifolds, multi-point locking is standard and PAS 24 security accreditation is available on request.
The coating
Look for powder coating to the QUALICOAT standard and ask how long the finish is guaranteed for. Our powder coating is QUALICOAT-rated and guaranteed for 10 years against discolouration, flaking and UV fading.
The guarantee, and what it depends on
Read what each part of the product is covered for, and the conditions attached. Our guarantee on bifold doors, bifold windows and sliding patio doors covers:
| Component | Guarantee | Covers |
|---|---|---|
| Aluminium profile | 10 years | Structural integrity |
| Powder coating | 10 years | Discolouration, flaking and UV fading |
| Glass units | 5 years | Moisture inside the sealed unit |
| Locks, hardware and handles | 1 year | Oxidisation |
Like most manufacturer guarantees, it assumes correct installation and regular maintenance: cleaning with soap and water and lubricating the hardware every six months. Pass those care instructions on to your customer at handover. It's the simplest way to cut call-backs.
Visit the factory
A factory visit tells you more than a brochure. You can see how frames are cut, assembled and checked, how stock is held, and how dispatch is organised. Our factory in central Leeds welcomes visits by appointment, Monday to Friday, 8:30am to 5:00pm.
Who buys aluminium windows and doors at trade?
Window and door installers
Installers make up our largest group of trade customers. For them, short lead times and fixed dates turn into more jobs fitted per month, and unglazed supply makes for easier handling on site.
Builders and main contractors
On an extension or new build, the doors and windows sit on the critical path. A fixed delivery date lets you programme the fitting around the steelwork, roof and screed, rather than leaving the opening boarded up.
Garden room companies
Garden room firms often need the same few sizes repeatedly, in quick succession. Bifolds in 2 to 7 panels, up to about 7,000mm wide, cover most fronts, and we can deliver to the garden room company, the builder or straight to the end customer. See our garden room bifold doors page for typical specifications.
Architects and specifiers
Specifiers need a system with documented performance and a fabricator who can make what's drawn. Ask us for project-specific U-values with the system, configuration, sizes and intended glass, and for product specifications such as cill and threshold options.
Glazing companies
Glazing firms often order unglazed and fit their own units, which plays to the fastest lead time and lets them control the glass specification.
A checklist for choosing a trade supplier
Ask every supplier on your shortlist the same questions and compare the answers side by side:
- Do you make the frames yourselves? If not, who does?
- Which aluminium system do you use, and are you accredited by the system company?
- What are the system's tested classes for air, water, wind and security?
- What's the lead time in working days, glazed and unglazed, in stock and non-stock colours?
- Is the delivery date fixed when I order, and who actually delivers?
- Can you deliver to site, my yard or directly to my customer?
- Is there a minimum order? How quickly can an account be opened?
- Will I get a price list I can quote from, and does pricing improve with volume?
- What exactly does the guarantee cover, for how long, and on what conditions?
- Can I visit the factory and see the products being made?
Mazuli trade accounts
Mazuli is a fully accredited Cortizo manufacturer, founded in 2020, with a 25,000 sq ft factory in central Leeds. We fabricate aluminium bifold doors, sliding doors, windows, gable ends, residential, French and heritage doors in-house, supply Ultraframe roof lanterns and skylights, and deliver across the UK mainland on our own fleet. We supply and deliver; we don't install, so the fitting stays with you.
To open an account, call 0113 827 5596 or email sales@mazuli.co.uk with a short description of your business and the work you do. See our trade accounts page for the full terms, browse the aluminium bifold doors, patio sliding doors and casement windows pages for specifications, or read our guide to aluminium bifold doors. For a price on a specific job, request a quote.
