"What is the price per square meter?" is almost always the first question a buyer asks an aluminium fabricator, and it is almost always the question that produces the least usable answer. Not because suppliers are being evasive, but because a cost-per-square-meter figure is a ratio, and both the top and the bottom of that ratio move independently. Change how the area is counted and the same window can look cheap or expensive without a single component being altered.
This guide is written for people who have to compare two quotes that arrived in different formats. It does not publish a price list, because a price list without a specification behind it is not a quote. What it does instead is show you which lines on a specification sheet move the number, how the area itself gets defined, and what to put in a request for quotation so that the answers you get back are genuinely comparable.
A typical factory quotation priced by area covers the manufactured unit: aluminium profile, thermal break strip, the insulated glass unit, the hardware set, gaskets and seals, fabrication labour, and export packaging. That is a fairly consistent bundle across serious fabricators, which is why area pricing works at all.
What it usually does not cover is everything that happens after the crate is sealed: sea or air freight, insurance, import duty and taxes, port handling, delivery to site, crane or scaffolding time, installation labour, removal of old frames, making good the reveals, and any third-party certification testing required by the local authority. On a villa project those excluded items can add up to a meaningful share of the landed figure, and they vary by country far more than the window itself does.
So the first clarifying question is not about price at all. It is about the basis: is this ex-works, FOB, CIF, or installed? Two quotes that appear to differ by a wide margin on a per-square-meter basis are frequently much closer once both are converted to the same basis.
Two casement windows can look identical in a photograph and differ substantially in cost to build. The difference sits in six places, and every one of them is checkable on paper before you commit.
| Spec line | Lighter build | Heavier build | Why it changes the cost |
|---|---|---|---|
| Alloy temper and wall thickness | Unspecified alloy, thinner walls | 6060-T66 at 1.8 to 2.0 mm on casement lines | Aluminium is bought by weight. Every tenth of a millimetre of wall thickness is real material on every linear metre of frame and sash. |
| Thermal break strip | Narrow strip, generic material | PA66GF25, multi-chamber, 34 to 44 mm on some series | The strip is a separate bought-in component and a separate crimping pass on the production line. Wider and multi-chamber strips cost more in both material and machine time. |
| Glass build-up | Basic double glazing | Low-E coating, laminated pane, argon fill, triple glazing | Glass is one of the largest single bought-in items. Coatings, lamination and gas fill each add a step, and heavier units cascade into heavier hardware. |
| Hardware set | Unbranded, untested | ROTO, Winkhaus, CMECH, Wehag; cycle-tested sets | A named brand is a named purchase price. Cycle-tested hardware implies documented test evidence, which is a real cost to hold. |
| Sealing layers | Single or double seal | Triple sealing, or a dual-matrix eight-layer system | More seals mean more material, more notching operations, and welded or vulcanised corners rather than mitred ones. |
| Corner assembly | Mechanical crimping only | Full glue-injection process, injection-moulded structural adhesive | Adhesive, dispensing equipment and curing time are all added cost per corner, and they are the difference between a frame that stays square and one that weeps. |
None of these lines is optional information. If a quotation says "high-grade aluminium" without a temper, or "thermal break" without a strip material, or "German hardware" without a brand, it is not a specification. It is a description, and descriptions cannot be compared.
The area side of the ratio is where most of the confusion lives, and it comes down to three things.
Area can be taken over the outer frame dimension, over the structural opening, or over the visible glass only. On a window with a frame width of around 116 to 119 mm, the outer-frame figure and the glass-only figure are not remotely the same number, and dividing by the smaller one produces a much larger cost per square meter for the identical unit. Always ask which of the three was used.
Most fabricators apply a floor to how little they will bill for a single opening, because a small window still consumes a full saw cycle, a full hardware set and a full corner assembly. A bathroom or stairwell window priced on actual area looks expensive; priced at the floor it is simply normal. This is why a project with many small openings has a genuinely higher cost per square meter than a project with the same total area spread across fewer, larger units.
Handle, transmission box, anti-pry lock points, hinges, fall-rope safety device, drainage covers, and the screen sash are all bought per unit. A 0.6 square metre window and a 2.4 square metre window carry essentially the same hardware cost. Spread that fixed cost over four times the area and the large window's cost per square meter drops sharply.
Put those three together and one rule falls out: cost per square meter falls as average opening size rises, for a constant specification. That single sentence explains more apparent pricing contradictions than any other. It is also why comparing your per-square-meter figure against a figure quoted for someone else's project is close to meaningless unless the size mix is similar. Mullions and combination units add one more wrinkle: a wide opening built as fixed plus operable plus fixed is manufactured and priced as several units joined together, not as one large panel.
Once you know the six cost drivers, a product data sheet stops being marketing and starts being a map of where the money went. The table below uses four real series from the ALPES catalogue purely to show the reading method; the same method works on any fabricator's sheet.
| Series | Frame width | Glass sash thickness | Wall thickness | K-value | Hardware | What it tells you about cost |
|---|---|---|---|---|---|---|
| C120 Outward Opening | 119 mm | 62 mm | 1.8 to 2.0 mm | 1.6 | ROTO transmission box, anti-pry lock points | Widest frame here, full square cavity for wind load, injection-moulded structural adhesive on frame, sash and screen. Structural capability is where the money is. |
| C113 Outward-Open | 113 mm | 57 mm | 1.8 to 2.0 mm | Not the headline number | CMECH, 30,000-cycle tested | Slimmest glazing pocket in the group, so the cheapest glass capability. Full glue-injection corners and triple sealing still put it well above entry level. |
| C116 Outward-Open | 116 mm | 81 mm | 1.8 to 2.0 mm | 1.7 | Wehag upgrade available | 34 to 44 mm multi-chamber insulation strips and a 22 mm slim mullion. You are paying for thermal performance and sightlines, not for bulk. |
| AW90 Passive, inward-open | 90 mm | 90 mm | 1.8 mm | 1.3 | Winkhaus, optional C-slot ROTO | Narrowest frame, deepest sash, dual-matrix eight-layer sealing, 240-hour salt spray and 5,000 N shear figures on file. This is the top of the range and the spec sheet says so. |
Two readings worth internalising. First, glass sash thickness is a statement about glazing capability: 57 mm, 62 mm, 81 mm and 90 mm pockets support progressively heavier glass build-ups, and heavier glass is one of the largest single cost items in any window. Second, the step from a K-value of 1.6 down to 1.3 is not a rounding difference. Getting below roughly 1.5 in an aluminium frame generally takes wider multi-chamber strips, more sealing layers and better glass, all three of which are paid for.
If you are still settling the opening layout at this stage, it is worth fixing casement window sizes before you ask anyone for a number, because the size mix drives the denominator more than any other single input.
A retail or installed quote and a factory quote are different products wearing the same units. The installed figure carries site survey, removal and disposal of old frames, installation labour, sealants and flashings, scaffolding or access equipment, warranty call-outs, and the paperwork that goes with local building control. The factory figure stops at the crate. Converting between them is where most "the factory is cheaper by X percent" claims quietly fall apart.
Being honest about where the local supplier still wins matters more than winning the argument. A local fabricator or dealer can usually attend site the same day or the next, speaks the language of the local inspector, produces the compliance documentation your authority actually expects, carries van stock of common spares, and handles a single damaged sash as one small job. On a one-off replacement or a tight programme with no float, that is worth real money.
What a direct factory relationship buys you in exchange is traceability. When a window is manufactured against a recorded order with a named profile series, a named hardware brand and a recorded colour batch, a single sash can be remade to the original specification years later instead of replacing an entire elevation because nothing matches. For a developer running the same window type across dozens of units, that consistency is usually the deciding factor, not the unit price. Choosing a casement window supplier who can hold a specification constant across phases is often worth more than shaving a little off the first order.
Send the same list to every fabricator. If you do, the quotes come back sortable, and the per-square-meter figure finally means something.
| Ask for | Why it matters | Red flag in the reply |
|---|---|---|
| Per-opening dimension schedule with quantities | Fixes both the denominator and the size mix | "Our average price is X per square meter" with no schedule |
| Definition of the measured area | Outer frame, structural opening and glass-only give three different rates | No answer, or "standard practice" |
| Alloy temper and measured wall thickness in mm | Drives material weight and wind-load capacity | "High-grade aluminium" with no temper and no number |
| Insulation strip material and width | PA66GF25 with a stated width is verifiable | "Thermal break" with no material and no dimension |
| Full glass build-up | Pane thickness, spacer, gas fill, coating, lamination | "Double glazing" as the entire description |
| Hardware brand and any cycle or corrosion test | Named brands are priced and traceable | "German hardware" without a brand name |
| Sealing layer count and corner method | Triple sealing and glue-injected corners cost more and perform differently | Silence on how corners are joined |
| Screen mesh specification | Standard stainless mesh and anti-PM2.5 mesh are different products | "Screen included" with no mesh grade |
| Finish and colour, standard or custom | Custom matching adds a setup step and a minimum quantity | Colour listed without saying whether it is stock or matched |
| Basis of the price: EXW, FOB, CIF or installed | The single largest source of apparent price gaps | A rate with no basis stated anywhere |
| Certification or test reports required by your market | Testing is a real cost and a real lead time | "We can provide any certificate you need" |
The metric is not useless; it is just frequently used too early and on too little information. It works well in three situations.
The method is always the same order of operations: fix the schedule first, compare totals second, and divide by area last. Doing it in that order is the difference between a number you can defend and a number that falls apart the moment someone asks a follow-up question.
If you have a dimension schedule and a target specification, the fastest path to a usable figure is to send both and ask for a per-opening breakdown rather than a single blended rate. A blended rate hides the fact that your small openings are carrying the fixed hardware cost while your large ones are subsidising them, and that hidden cross-subsidy is what makes later change orders so surprising.
For a discussion of the casement window price structure across our outward-opening and inward-opening series, or to send a schedule for a per-opening quotation, reach the team through the ALPES contact page. Bring the schedule, the glass build-up you want, and the hardware brand you are willing to accept. That is enough for a quote you can compare.
