The window and door supply chain: manufacturer, wholesaler and intermediary

When an end customer pays for a window, that price has passed through a chain of hands: the system house that produces the profiles, whoever assembles the window, whoever stocks it, whoever resells it, whoever installs it. Each step adds a cost or a value — sometimes both, sometimes only the first. The trouble is that from the outside the supply chain looks like a black box: the retailer sees a price list, the window fitter sees a price per square metre, and rarely understands how many links there are between the raw profile and what the customer actually signs for.

This article is a map. It doesn’t cover how to negotiate terms (that’s a different topic) or whether it’s worth producing in-house versus buying finished product (also a different topic). Here I’m only explaining how the chain is structured, who the players are, where real margin is created, and where it’s eroded in steps that add nothing. The aim is to help you understand where you sit and, as a result, how many hands touch the product before it reaches you.

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The players in the chain, one by one

Before talking about margins, the roles need to be clear. In the window and door sector, the terms are often used loosely — “wholesaler”, “manufacturer”, “distributor” get mixed up as synonyms when they aren’t. Let’s put things in order.

Player	What they actually do	What they DON’T do
System house (e.g. Salamander)	Designs and extrudes PVC profiles, carries out ITT testing, issues technical documentation	Doesn’t assemble the finished window
Manufacturer / industrial window fabricator	Buys profiles, cuts, welds, fits hardware, glazes: builds the finished, made-to-measure window	Doesn’t normally sell to the end consumer
Wholesaler / distributor	Buys finished or semi-finished product, holds it in stock, resells it with a range and quick delivery	Doesn’t manufacture to measure, doesn’t design
Intermediary / agent / broker	Connects supply and demand, takes a commission	Doesn’t own the goods, doesn’t process them
Retailer / showroom	Sells to the end customer, handles quotes and the commercial relationship	Often neither manufactures nor stocks
Installer / fitting contractor	Installs on site, manages the works	Isn’t always the one who sold the product

The confusion arises because a single business can cover more than one role. A manufacturer with its own plant can sell direct wholesale (making it its own wholesaler); a large retailer might hold some stock and behave like a mini-distributor; a fitting contractor might both install and resell. Understanding who you’re dealing with means understanding how many functions they actually perform — not which label is on their business card.

A useful clarification, given that LMT is a manufacturer under Italian management using German Salamander CE-marked profiles: the manufacturer is whoever physically transforms the profile into a finished window. That’s not a commercial step, it’s an industrial one. This is the structural distinction to keep in mind throughout this article.

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How many steps there actually are

The classic “long” supply chain — the one the end customer pays for without knowing it — takes this shape:

System house → Manufacturer → Wholesaler/Distributor → Retailer → End customer (with the installer slotting in at the end, sometimes the same party as the retailer).

That’s four commercial steps before the customer. Each is legitimate if it adds something; each is a cost if it doesn’t.

The “short” chain, the one that matters to anyone buying to resell, skips links:

System house → Manufacturer → Retailer → End customer.

Here the retailer or window fitter buys directly from the manufacturer. One step disappears (the wholesaler) and, where present, the intermediary too. That isn’t automatically “better”: it depends on what that step was giving you. If the wholesaler guaranteed you instant stock and your business runs on quick delivery, skipping it costs you in logistics. But if the wholesaler was just a party buying from the manufacturer and passing the goods on to you with a mark-up, then it was a link with zero value for you.

The right question isn’t “how many steps can I cut?” but “is every step I’m paying for giving me a service I couldn’t provide for myself?”

For anyone wanting to go further upstream — into the make-or-buy question of whether it’s worth becoming a manufacturer yourself — there’s a dedicated analysis on producing in-house versus buying for resale.

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Where margin is created and where it’s eroded

Now for the core question. Every player in the chain has a margin, and each margin has a different economic justification. Let’s see where real value is created and where it’s just erosion — a cost that builds up without any corresponding service.

Link	Margin justified by	When it becomes erosion
Manufacturer	Industrial transformation, made-to-measure, certification, warranty	Almost never: this is who creates the product
Wholesaler	Capital tied up in stock, product range, quick delivery, unsold-stock risk	When reselling to order without holding stock
Intermediary/agent	Business development, territorial coverage	When they simply “pass on the contact”
Retailer	Customer relationship, quoting, aftercare, showroom	When they only add a mark-up on someone else’s catalogue
Installer	Installation to a proper standard, responsibility for the works	Rarely: the value is in the workmanship

The manufacturer’s margin is the “healthiest” in the chain, because it rewards a physical transformation: profiles cut, welded, hardware fitted, glass installed, checks carried out, CE marking under EN 14351-1. That margin isn’t a commercial mark-up, it’s the price of the fact that, before, the product didn’t exist.

The wholesaler’s margin is justified when the wholesaler does their real job: tying up capital in stock, taking on the risk of unsold goods, giving you product tomorrow instead of in five weeks’ time. That stock has a cost (capital locked up, space, model obsolescence) and their margin rewards it. But if the wholesaler doesn’t hold stock and only orders from the manufacturer once you’ve placed your order, then you’re not paying for stock: you’re paying for an invoicing step. That’s the case worth recognising.

The intermediary’s margin is the most variable. An agent who brings you volume, opens up a territory, develops clients for you earns their commission. A broker who simply passes your name to a manufacturer — pocketing a percentage that ends up in the price you pay — is pure erosion: you’re paying for a contact you could have found yourself.

A word of caution: the real margins at each link vary enormously by product range, volume, geography, period and the individual operator’s structure. Anyone who gives you a flat percentage (“the wholesaler adds 30%”) is making it up. As an order of magnitude, the price indicatively rises at each commercial step, but by how much can’t honestly be generalised. The point of this article isn’t the number: it’s understanding which steps reward a service, and which don’t.

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Buying directly from the manufacturer: what actually changes

Skipping the intermediate links and buying from the manufacturer changes two things, and it’s worth keeping them separate because they’re often conflated.

The first is the starting price. Buying from the manufacturer, you start from the industrial cost plus their margin, without the wholesaler’s mark-up or any intermediary’s commission. On continuous volumes this is felt, because every step skipped is a margin that doesn’t end up in your cost. It doesn’t mean “rock-bottom prices” — a serious manufacturer doesn’t undersell, because a healthy margin is what lets them stay in business and guarantee you continuity — but it does mean starting from the lowest possible base in the commercial chain.

The second, often more important, is control. Buying from the manufacturer gives you a single point of contact on production: made-to-measure configurations without going through a stock catalogue, lead times negotiated directly with whoever cuts and welds, specification details discussed with whoever executes them, technical documentation (DoP, CE marking) issued by whoever makes the product. With a wholesaler, on all this, you have a middleman: if you ask for a change, they pass it to the manufacturer and pass the answer back to you. Every extra step in the information chain is a point where something gets lost or slowed down.

The other side of the coin, to be said honestly: buying from the manufacturer means giving up the wholesaler’s quick delivery. If you have a job tomorrow and you’re missing a piece, the distributor’s stock saves you. The manufacturer works to order, on production lead times. That’s why many professionals keep a foot in both models: the bulk of volume from the manufacturer, urgent needs from the wholesaler. That isn’t inconsistency, it’s risk management.

For how direct purchasing at manufacturer terms actually works, see the dedicated page on wholesale supply for retailers and window fitters, while the industrial side — who manufactures and with which systems — is described in the production and plant section.

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When the wholesaler adds real value (and when it doesn’t)

The wholesaler isn’t “the villain of the supply chain”. Done well, it’s a link that solves real problems. It’s worth listing when it genuinely pays to go through a distributor.

The wholesaler adds value when:

• They hold real stock and give you quick delivery on standard products, keeping a job site from stalling for want of one piece;
• They offer a wide range of brands and models that no single manufacturer covers, useful if you resell mixed product ranges;
• They break down volumes: selling you the small quantities that a manufacturer, geared to full batches, would struggle to handle or would offer on worse terms;
• They take on the unsold-stock risk for you, so you don’t tie up capital in warehousing.

The wholesaler is just an extra step when:

• They hold no stock and only order from the manufacturer after you’ve placed your order (in that case you’re paying a mark-up for a stock service that doesn’t exist);
• You always buy the same product, in volume and consistently: at that point, a direct relationship with the manufacturer gives you better terms and zero intermediation;
• You need made-to-measure: the wholesaler works from a stock catalogue, not on special configurations, and would end up passing the request on to the manufacturer anyway.

The practical rule: the more standard, urgent and fragmented your purchase, the more the wholesaler makes sense. The more continuous, made-to-measure and plannable, the more it pays to go direct to the manufacturer. Many professionals sit in the middle and use both.

If your leverage is continuous volume, the next step from this map is understanding how to structure the deal: I cover it in the guide on how to negotiate price lists and volume discounts with a manufacturer.

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Where you sit

Once the map is clear, the question becomes personal: which link are you in, and which one can you own best?

If you’re a retailer or a showroom, your value is the relationship with the end customer and the quoting process: there, you’re irreplaceable. But on the supply side you’re a buyer, and it’s worth shortening the chain upstream — buying from the manufacturer when volume justifies it, from the wholesaler when you need range or urgency.

If you’re a fitting contractor, your value is the installation and the responsibility for the works. On the product itself, again, you’re a buyer: same reasoning applies.

There’s also a lever many people underestimate: moving up the chain by selling under your own brand. Instead of reselling someone else’s product with a mark-up added (an erodible margin), you can have windows manufactured under your own brand by a manufacturer on a private-label basis — becoming, in the customer’s eyes, the “manufacturer” yourself. It changes both the margin and the perception. It’s an area with specific implications (including on liability), covered in private label, third-party manufacturing and margin for the retailer, with the operational page on private label manufacturing.

And what about the profile system? Knowing that behind a window sits a system house like Salamander, with ITT testing and documentation, is what lets you sell certified performance instead of “just any window”. The relationship between window fabricator and profile system is explained in Salamander for window fabricators.

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When it’s NOT worth shortening the chain

Cutting steps isn’t always the right move. There are situations where the wholesaler or intermediary do a job that, if you take it on yourself, costs you more.

• When your volumes are low and irregular. If you buy few pieces, scattered and always different, the manufacturer won’t give you better terms than the wholesaler — in fact, they may handle you worse, because you’re not a plannable customer. The distributor’s stock and ability to break down volumes work in your favour here.
• When you live on quick delivery. If your model is “the customer wants it now”, the manufacturer’s made-to-order production won’t keep pace with your timescales. The wholesaler’s stock is your service, and paying for it is rational.
• When range matters more than price. If you resell many product ranges and brands, no single manufacturer covers them all. A multi-brand distributor saves you dozens of separate supply relationships.
• When you don’t have the structure to manage the direct relationship. Buying from the manufacturer means placing well-formed orders, managing specifications, planning ahead. If you don’t have someone to handle that, the wholesaler’s intermediation simplifies your life — and that service has a value.
• When the intermediary brings you clients you wouldn’t otherwise have. An agent who opens up a territory or a new channel for you isn’t a cost: it’s business development. Cutting them to save the commission, and losing those clients, is an own goal.

In summary: shortening the chain pays off when you have volume, continuity and structure. Otherwise, the intermediate links are doing a job you’d pay more for if you did it yourself.

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FAQ

What’s the difference between a wholesaler and a window manufacturer?

The manufacturer physically transforms profiles into finished windows: cutting, welding, fitting hardware, glazing, certifying. The wholesaler manufactures nothing: they buy products (finished or semi-finished), hold them in stock and resell them with a range and quick delivery. The manufacturer’s margin rewards an industrial transformation; the wholesaler’s rewards stock and availability. They’re different roles, even though a manufacturer with their own plant can sell directly wholesale.

How many steps are there between the profile and the end customer?

In the classic long chain there are four commercial steps: system house → manufacturer → wholesaler → retailer → customer. In the short chain, the retailer or window fitter buys directly from the manufacturer, skipping the wholesaler (and any intermediary), so the commercial steps before the customer drop to two. Which is worthwhile depends on the service each link genuinely gives you.

Does buying from the manufacturer always pay off compared with the wholesaler?

No. It pays off when you have continuous volume, need made-to-measure product and can plan your orders: you start from the lowest base in the commercial chain and get direct control over lead times and specifications. It doesn’t pay off if you live on quick delivery or buy a few scattered pieces: in those cases, the wholesaler’s stock and range are worth their cost. Many professionals use both channels.

Where does margin get eroded in the window and door supply chain?

It’s eroded at every step that adds a mark-up without a corresponding service: a wholesaler reselling to order without holding stock, an intermediary who just “passes on the contact”, a retailer who applies nothing more than a mark-up on someone else’s catalogue. It isn’t eroded where there’s a real service: industrial transformation, capital tied up in stock, genuine business development, installation to a proper standard.

How much margin does each link in the chain add?

There’s no figure that can be honestly generalised. Each player’s margin varies enormously by product range, volume, geography, period and the individual operator’s structure. Indicatively, price rises at each commercial step, but by how much can’t be stated as a percentage without making it up. The useful reasoning isn’t about the number, but about which steps reward a service and which are just intermediation.

Is an intermediary or agent always a cost to cut?

No. An agent who brings you volume, opens up a territory or develops new clients for you earns their commission: that’s business development, not erosion. It only becomes an unnecessary cost when they simply pass on a name you could have found yourself. The distinction is between those who create commercial opportunities and those who just pass on a contact.

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Conclusion

The window and door supply chain isn’t a chain of “intermediaries to cut”: it’s a sequence of functions, some of which add real value and others only cost. The manufacturer transforms, the wholesaler stocks, the intermediary develops, the retailer sells, the installer fits. Every margin is healthy as long as it rewards a service you couldn’t provide for yourself — and becomes erosion when it’s just an invoicing step.

For the trade professional, the lesson is one: what matters is understanding where you sit and how many hands touch the product before it reaches you. If you have volume, continuity and structure, shortening the chain by buying from the manufacturer gives you a lower starting price and direct control. If you live on urgency and range, the intermediate links are doing a job you’d pay for anyway.

If you want to see how direct purchasing at manufacturer terms works, without the intermediate steps, the starting point is the page on wholesale supply for retailers and window fitters.