ALPES Aluminum Windows and Doors Designer: Six People Hold That Title, and None of Them Can Design a Section for Your Project

The Word on the Door Is Not a Job Title

A project team will say "the designer" and everybody in the room will picture a different person. The architect hears the practice that drew the elevation. The contractor hears the supplier who will issue the fabrication drawings. The client hears whoever chose the colour. The factory hears a piece of software with the word in its product name. All four are right, and they are not talking about the same work.

That ambiguity would be harmless if the four jobs were sequential versions of each other. They are not. They are four different kinds of authority over four different things, and the thing none of them can do is the thing most buyers assume they are paying for.

A section is the shape of the metal when you cut through it and look at the cut end. Every chamber, every drainage path, every sealing groove, every screw boss, the depth of the glazing rebate, the width of the thermal break and the pocket that receives the lock are all decided in that shape. And that shape is made by a die, in a tool shop, for a profile range, before any of your openings existed. Once the die is cut, the section is finished. Everything that happens afterwards is selection.

This is not a complaint about the industry. It is the reason a window catalogue is not an options list. It is a constraints list, printed in the format of an options list, and handed to a designer who was trained to read options lists.

Six People Who Are Called the Designer

Below is the honest version of the word. The third column is the one that matters, because it tells you when that person stops being able to help you.

Who is meant	What that person actually decides	When they lose their influence	What they cannot decide	Where you will find their name
The architect or building designer	Where the openings are, what they look like, what performance the building needs, and what the wall is made of	When the shop drawings are approved and the order is released	Anything inside the section: chamber layout, drainage route, rebate depth, hardware groove	Elevations, plans, the window schedule, the specification
The facade or building-enclosure consultant	Which performance classes and test standards apply, and how the interface to the wall is detailed	Once the performance brief is issued and the system is chosen	They do not manufacture or warrant the product, and they cannot sign a local approval	Performance specification, review comments, test witness reports
The system-house profile designer	The section itself: chambers, thermal break position, drainage, hardware pocket, glazing rebate	Years before your project, when the die was cut	They are not working on your building and never will be	Nowhere you will see, unless you ask for the section drawing
The fabrication or shop-drawing designer	How the elevation becomes cut lengths, hardware sets, drainage holes and a buildable window table	Once the drawings are approved and material is cut	They may not change the design intent; an unflagged departure is an unapproved change	Shop drawings, cut lists, hardware schedules
The industrial designer of the hardware	How a handle feels and looks; occasionally wins a design award for it	Long before your project	Nothing about the window it is fitted to	A badge in a supplier catalogue
The configurator called a designer	Nothing. It selects a product, a style and a size, then prices it	It never had any	It cannot measure your wall, and it does not carry code responsibility	A web form

Read the third column downwards and the whole article appears in miniature: the people who can still change things are the people with the least knowledge of the section, and the person who knew the section best stopped being reachable years ago.

Four Things in This Industry Called Design

The word does more damage because it is attached to four nouns, and each noun belongs to somebody else.

The term	Whose design it actually is	What it obliges	The mistake it invites
Design pressure	The building. Published guidance states that selecting window units begins with calculations by the project structural engineer or architect, using the wind-load method in the applicable load standard	A number the building imposes on the window	Asking a factory what the design pressure of your project is. It is not ours to give
Design award	A hardware brand's industrial designer, for a handle	Nothing about the window	Treating an award on a component as evidence about an assembly
Section design	The system house, at the time the die was cut	Everything the window can ever do	Believing a project can commission one
Design software	A vendor, for a factory's ordering process	Speed, and consistent repetition	Letting a default value stand in for a site measurement

Only the first of those four is a designer's own work product, and it is a load, not a window. That is the whole confusion in a single line: the one thing in this industry that legitimately carries the designer's name is not part of the product.

What the Code Actually Asks the Designer to Do

This is where the word stops being a marketing problem and becomes a documented one. Several published regulatory instruments in China describe the split precisely, and they are unusually explicit about who draws what.

Task	Who is named as responsible	What that means in practice
Elevation subdivision and opening design	The building design institute	The designer owns the layout of the holes, not the shape of the thing that fills them
Stating the key performance indicators	The building design institute, in the main design documents	Wind resistance, water tightness, air tightness, thermal, acoustic and operating-cycle durability must be written down by the designer, not discovered later in a catalogue
Window-specific detailing design (the deepening design)	The main design institute, or an enterprise with window design capability	When a non-main institute prepares it, the main institute must carry out a technical re-check and issue a written re-check record before it goes to drawing review
Review of specialist deepening-design documents	The original design institute, by seal and signature, and it is answerable for what it reviewed	The party that draws the fabrication detail is not the party that carries the review responsibility
Joint review before structural work starts	The developer convenes design, supervision, main contractor and the window manufacturer	A design-drawing review confirmation record is to be produced. This is the last moment a change is free
Public disclosure of the section	The developer, at the sales and construction site	Heat transfer coefficient, shading coefficient, the window section and any energy label are to be published. The section is treated as a public document, not as internal factory data

Two lines in that table are worth more than the rest of this article. The first: the designer's named duties are subdivision and openings, plus writing the performance figures down. Not one word about the section. The second: the detailed fabrication design may be produced by the manufacturer, but the original design institute must seal it and is answerable for what it reviewed.

So the arrangement is not "the architect designs and the factory makes". It is: the factory details what the architect specified, and the architect signs for the detailing. One document, two authors, only one of whom can sign.

The last row is the one designers never ask about and should. If a local instrument in our own district requires the window section to be published alongside the thermal figures, then the section is not something a supplier may legitimately keep vague. You can ask for it, and you should ask for it early, because it is the only drawing in the whole package that shows the seven things described further down.

The Section Was Designed Before You Were Asked

A custom aluminium section is not drawn into existence. It is extruded through a die, and the die is a block of tool steel that has to be designed, machined, heat-treated, nitrided, trialled and corrected. Published supplier guidance is consistent about the sequence and remarkably inconsistent about the clock.

Stage	What has to be true before it starts	Published durations (one column per source, not reconciled)
Profile design and optimisation	Performance targets or preliminary drawings; wall-thickness uniformity, tongue ratios and corner radii reviewed for extrudability	One to two weeks for brief and drawing review; two to three weeks for cross-section modelling and structural analysis
Die design and manufacture	The cross-section is frozen. Frozen means frozen	Seven to eight days for sections under about 150 mm diagonal; twelve to seventeen days for 200 to 350 mm diagonal. Another source: seven to twelve days. Another: four to six weeks for simple shapes, up to twelve or more for multi-hollow dies
Trial extrusion and sample approval	The die exists and has run sample lengths	Trial lengths of roughly six to ten metres; at least one round of correction should be budgeted on complex hollow sections
Production extrusion and finishing	Sample signed off	Fifteen to eighteen days for extrusion plus surface treatment; twenty to twenty-five working days end to end in one published figure, ten to sixteen weeks in another
Economics that never change	Nothing	Tooling is a fixed upfront cost that does not scale with volume: the die costs the same whether it runs a few hundred kilograms or tens of tonnes. That is the origin of minimum order quantities

We are not going to pick a number for you. The point is the spread: for the same activity, published sources differ by more than an order of magnitude, from under a fortnight to a full quarter. Any schedule that assumes a new section is a six-week activity and any schedule that assumes it is impossible are both reading somebody's marketing page.

What every source agrees on is the ordering, and the ordering is the argument. The section is finalised and frozen before tooling begins. There is no stage in that table at which a project team gets to adjust the chamber layout of the profile it just chose. There is a stage at which it can reject the profile and choose another one, which is a different act with a different verb.

One Section Has to Solve Seven Problems at Once

If you want to know why the section cannot be redesigned late, look at how many jobs it is doing simultaneously. A published method for reading an aluminium frame cross-section walks from the outside face to the inside face through seven distinct zones. Not one of those zones appears on an elevation.

Zone, outside to inside	The job it does	Visible on an elevation	If it was got wrong
Outer weather seal	Knocks the energy out of driven rain before it reaches deeper zones. It is not meant to be watertight	No	Everything behind it is asked to do a job it was not sized for
Outer face and drainage chamber	Pressure-equalised cavity; collects what gets past and drains it by gravity through concealed slots	No	Wind drives trapped water inwards instead of letting it fall out
Thermal break zone	Separates the two aluminium halves; its width, continuity and position govern the frame's thermal behaviour	No	Condensation on the room-side frame in winter, and a number that looks fine on glass but poor on the assembly
Inner face and reinforcement chambers	Accepts stiffening for wind deflection; carries the screw bosses that hardware is fixed into	No	Deflection under load, or fixings that pull out of thin metal
Hardware pocket	Receives the lock, cam or stay. Dimensioned separately because it must match the chosen hardware exactly	No	A pocket a millimetre too shallow and the lock tongue does not engage
Glazing rebate, bead and gaskets	Holds the sealed unit, seals it on both faces and allows it to expand	Only as a line	The glass you specified does not fit the rebate that exists
Interior trim channel	Conceals fixings and often doubles as a condensation gutter feeding the sill drainage path	Yes, as a shadow line	Winter moisture with nowhere to go

Seven zones, one drawing, no elevation. A designer can move every one of those zones by moving to a different system; a designer cannot move one of them without moving all of them. That coupling is what makes the section a single decision rather than a list of preferences, and it is why "can you just move the drainage slot" is not a small request.

Where the Two Designs Meet: The Shop Drawing

There is a moment where the architect's design and the factory's design have to be reconciled into one document. In most of the world that document is called a shop drawing, and the rules around it are unusually clear.

Question	Design drawings	Shop drawings
What question does it answer	What needs to be built	How we will build it
Who produces it	Architect and consulting engineers	The party fabricating or supplying the element. Window and door schedules are routinely listed as an example
Who must approve it	Forms part of the contract documents	Reviewed by the engineer or architect of record before fabrication starts, commonly within five to fifteen business days
What happens when it changes something	Defines the outcome and sets the requirement	It interprets the design; it does not change it. A departure that is not flagged is not a valid interpretation, it is an unapproved change
What it is used for afterwards	Permit, contract, pricing	The agreed record of what was fabricated. Deviation from approved shop drawings sits with the subcontractor; error inside approved shop drawings needs a harder conversation about who it came from

The sentence worth memorising is the one about interpretation. Shop drawings interpret the design. They do not change it. Much of the friction in this industry comes from a factory quietly resolving an impossible detail on your behalf, in a drawing nobody reads closely, and an architect signing a set that quietly no longer matches the elevation.

The Three Errors That Survive Every Review

Published guidance on residential shop drawings names the same three failures repeatedly. They are worth printing because all three are cheap to prevent and none of them is about workmanship.

The error	Why it survives review	The cheap prevention
Fabricating to architectural drawing dimensions without site measurement	The drawing is internally consistent, so nothing looks wrong on paper	Field-verify critical dimensions before final shop drawings, not after delivery
Coordination failure with adjacent elements	Each trade's own set is correct in isolation	One overlay drawing per opening, showing finishes, structure and services together
Revision control: shop drawings built from an earlier issue	The revision looks current because the title block was updated	Freeze a revision date and require every downstream document to name it

None of these requires a better product. All three require somebody to own a date. In our experience the third one is the most expensive, because it produces a building full of windows that were correct on the day they were drawn.

Eleven Numbers for the Eye, Thirty-Seven for the Building

Here is the part that no catalogue will tell you. We counted our own published parameters, from our own current product pages, and sorted them by who they serve. The count is ours, the numbers are ours, and you can repeat it on any supplier's table in twenty minutes.

Group	Distinct published values, in millimetres	Count	Who it serves
Sash width, the visible band around the glass	44.5, 53, 75, 96	4	The elevation
Frame width, the outer visible band	26, 36, 62	3	The elevation
Mullion visible face, the second of the two numbers	4, 21, 22, 31	4	The elevation
Subtotal, appearance	Combined	11	What the building looks like
Frame wall width, depth into the reveal	90, 112, 113, 116, 119, 126, 130, 155, 167, 182	10	The wall, not the drawing
Glass sash thickness, a stack dimension	43, 54.5, 55, 57, 62, 81, 90	7	Nothing you can choose
Mullion depth, the first of the two numbers	58, 72, 75	3	Span and wind, not looks
Track height, including the raised water barrier	8, 31, 43, 45, 53, 85	6	Accessibility and weather, and almost never on an elevation
Profile wall thickness	1.8, 2.0, 2.2, 2.5, 3.0	5	Standard compliance and local reinforcement
Published thermal value, three series only	1.3, 1.6, 1.7	3	System values, not whole-window values for your opening
Load figures, which are not one measurement	200, 220, 400 kilograms	3	Sash weight, pulley and drive capacity respectively
Subtotal, constraint	Combined	37	Whether the building stays dry, warm and operable

This is not a claim that appearance is unimportant. It is a claim that the ratio is invisible, that the invisible ratio is not accidental, and that a designer who does not know the ratio will spend the design fee on the eleven.

Reading the Table as Inputs and Constraints

Once you have split the columns, most specification arguments resolve themselves. Here is the same material reorganised the way a designer actually needs it.

Published row	Input you can set, or constraint you accept	The trap in the wording
Opening method	Input, but only within what the series offers. A tilt-and-turn series is not a sliding series	Changing the opening method late usually means changing the series, which means changing the section, which means re-starting the submittal
Visible bands: sash width, frame width, mullion face	Input, from the eleven	The narrow number quoted in marketing is often the frame; the band your eye reads is usually the sash. Ask which one is being described
Colour and coating	Input, from four standard colours plus matching	Colour is a batch, not a name. On a phased project the batch rule matters more than the swatch
Frame wall width	Constraint unless you also own the wall. In new build you do; in renovation you do not	Depth is a series property, not a function of track count. A four-track series in our range is shallower than some three-track series
Glass sash thickness	Constraint. It is a stack dimension, not the glazing rebate	Never infer glass thickness from it. The rebate is a section drawing number, not a catalogue number
Mullion pair, for example 75 over 21	First number is constraint, second is input	Anyone selling you on the second number alone has sold you nothing. The first number is the one that carries the span
Track height	Input, and the most consequential one that never reaches the elevation	A low track and a high water barrier are opposite answers. Decide it while the floor is still a line on a drawing
Load figures	Constraint, once glass is chosen	Three figures in our catalogue measure three different things. Sorting them into one descending column is the most common misreading of a sliding-door table

Glass Can Be Upgraded. The Section Cannot.

Designers are often offered a glass upgrade as the answer to a thermal target. Published technical writing on thermally broken aluminium puts a blunt sentence on this: the glass did not change, the frame geometry did. ｒｅｐｌａｃｅ the glass in a mediocre frame and you move one term; ｒｅｐｌａｃｅ the frame and you move the assembly.

Section-level decision	What published sources say about it	Can you change it for one project
Break width and continuity	Continuity matters as much as width: if the frame is broken but the threshold or coupling mullion bridges it, performance is lost where it is most vulnerable	No. Choose the system
The sill on a sliding system	A system with a thermally broken head and jamb but a highly conductive sill is not a balanced system, because the sill must carry rollers, manage water and take operational loads	No. This is exactly why the track-height row above is a design decision
Chamber proportioning	Several small chambers usually outperform one large open cavity because they limit internal air circulation; published guidance also cites a minimum chamber width to avoid convection	No
Isothermal alignment	Placing the polyamide bar on the same axis as the glass cavity creates a continuous isothermal surface. One of our own casement series states that the glass centreline, thermal break and equal-pressure seal sit on the same axis	No. It is already built into the section. That line in our catalogue is a report of a design decision, not an option
Hardware and fastener bridges	Screws, hinge plates, roller assemblies and fixing brackets can bypass the insulating break. Localised, but they add up around a frame	Partly: you can specify the hardware set and the fastener material, which is why they belong in the order, not on site
Glass build-up	Changes the sash weight, which interacts with load ratings, which interacts with the maximum panel size published for an assumed glass thickness	Yes, and this is the one lever that is genuinely yours. Use it knowing it moves two other numbers

The pattern is consistent: five of the six rows are bought, one is chosen. A thermal conversation that starts with glass is starting at the only row where you have freedom, which is comfortable, and ignoring the five where the outcome was fixed before the meeting.

The Designer That Is a Piece of Software

One more meaning of the word, because it is the one a buyer meets first. In this industry there is a configurator product literally named Window Designer. Its own description of what it does is the clearest definition of the word we have found: you ｓｅｌｅｃｔ the product, you ｓｅｌｅｃｔ the style, you ｓｅｌｅｃｔ the size, and it will give you a price.

What a configurator is good at	Where it stops, in the words of published guidance
Comparing ten or twenty units quickly and systematically	Where dimensions are uncertain, connection details are unresolved, or special installation conditions apply, no configurator replaces professional advice
Turning a choice into a price and a specification sheet	Software can produce performance data and check egress, but the designer remains responsible for confirming the product meets the local code
Keeping a repeated order consistent across a development	It works from what was configured for that business. It does not know your wall build-up unless somebody tells it
Speed of processing an order	A default value is a guess wearing a number. Published first-person accounts describe whole orders arriving too shallow because a default jamb depth was left in place for a deeper wall, and days lost building extension jambs on site

The last row is the whole problem with treating a configurator as a designer. A configurator does not ask how thick your wall is. It assumes one. And the assumed value is often a plausible one from a different country's standard wall, which is the most dangerous kind of plausible.

Send us the wall build-up layer by layer, outside to inside, in millimetres. That single line prevents more rework than any other sentence in an enquiry, and no software will ask you for it.

Five Numbers That Must Freeze on the Same Day

Everything above converges on one practical instruction. These five are decided by different people on different days, and they behave as one decision.

Number	Who usually owns it	What breaks if the others move first	Freeze it in writing by
Opening size in millimetres, stated as frame or as structural opening	Designer, from the structure	Every downstream number inherits the ambiguity	Before the window schedule is issued
Wall build-up, layer by layer, outside to inside	Designer, with the envelope consultant	Frame depth is chosen blind, and the interface detail is guessed	Before the series is selected
Glass build-up and the resulting sash weight	Designer, with the factory confirming	Load rating and maximum panel size were published for an assumed glass thickness	Before hardware is chosen
Track height and threshold condition	Designer, and it is a level decision as much as a product one	Accessibility or weather performance, and it cannot be corrected after the floor is poured	While the slab is still a line
Who signs the deepening design and who is first responder	Design institute and developer, on the record	A perfect product and a perfect installation, and nobody who will pick up the phone	Before the joint review meeting

What We Publish and What You Still Have to Ask For

The credibility of everything above depends on this section being blunt, so here it is bluntly. The right-hand column is the part suppliers never print.

We publish	What it actually is
A design award mentioned in one series	It belongs to a German hardware brand's handle. It is not our design and it is not the window's. It is the only place the word design appears in our catalogue, which is itself the point
One alloy and temper across every series	Because it is identical everywhere in our range, it cannot be the reason to choose one product over another. It is a floor, not a differentiator
Thermal values for three series	System values, not whole-window values, not calculated for your opening, and not transferable between series. Several series publish none
Isothermal alignment on one casement series	A description of a section that already exists. Useful as evidence, useless as a request
Two published durability figures on one series	They measure coating and substrate corrosion resistance, and composite bond strength. They are not air, water or wind ratings, and they do not transfer to other series
Two production centres	Ask which plant your order runs in. Colour batch, hardware platform and machining programme version can differ, and it is a reasonable question nobody asks

And the honest list of what is not there:

• We do not publish a maximum sash size and weight rating for most series, because it is a function of the hardware platform and the glass build-up. Ask for it against your configuration, not in the abstract.
• We do not publish glazing rebate dimensions in the specification tables. That number lives on the section drawing, and the section drawing is the thing to request.
• We do not publish air, water or wind performance classes across the range. Where a figure exists it belongs to a tested configuration, and the question is whether your configuration is covered.
• Our sliding window category holds one product, and it is a side-press window rather than an ordinary two-track slider. If your elevation was drawn around a standard two-track slider, we will say so rather than substitute a sliding door.
• Five category pages in our catalogue are empty: swing doors, folding doors, entry doors, sun rooms and tilt-and-slide. These are the products designers draw most often. If your design depends on modern bi fold doors, the honest answer is that we would be starting from nothing, and you should know that before you build a schedule on it.
• One tilt-and-turn page in our catalogue is a placeholder rather than a specification. We would rather say that than let a specification be written against it.

What a Designer Should Send Us

If the section cannot be designed for you, then the value has to come from somewhere else, and it comes from how completely the configuration is described. This block is written to be pasted into an email. The third column is what happens when a line is left blank, and it is the column that matters.

Line	A good answer looks like	Left blank, it becomes
Opening reference and count	One reference per distinct opening, with the number of each	A quotation priced on the average opening, which no project has
Size in millimetres, and which one it is	Width by height, labelled frame size or structural opening	A clearance assumption made twice, in opposite directions
Wall build-up, outside to inside	Every layer named, with thickness	A frame depth chosen against nobody's wall
Series and frame depth	Named, or explicitly left to the factory with the reason	Two bidders pricing two different products to the same description
Glass build-up, including spacer	Full make-up with spacer type, not a nominal thickness	A sash weight nobody calculated, against a rating nobody checked
Hardware platform and groove standard	Named brand and groove, with any optional platform noted	Two platforms with two different adjustment budgets, discovered in year three
Configuration, handing and the convention used	Which leaf moves, on which side, and whose left-and-right convention	Errors machined into the profile, which cannot be adjusted away on site
Track height and threshold condition	One of the published options, chosen against the finished floor level	An accessibility problem discovered at handover
Colour, and the batch rule	Colour name plus a written rule for phased deliveries	A replacement leaf in year five that does not match the wall
Performance figures the designer has written down	The values with the standard and the test configuration named	A supplier's marketing number where a specified value should be
Drawings required, and in what form	Section drawings, elevations and fabrication set, named up front	Discovery during the review period that half the package does not exist
Who signs the deepening design	A named entity, and who is the first responder after handover	A complete product, installed correctly, and a phone list

Ten Answers That Sound Like Answers

A designer will hear these from every supplier, including competent ones. The right-hand column is the one to keep.

What you are told	Why it carries no information	Ask instead
We can design it for you	Usually means selecting from an existing range. If it means a new section, ask about the die, the trial and the minimum quantity	Is this an existing die or a new one
It is fully customisable	Almost always means size and colour. Not chamber layout	Which rows on this table are inputs
German engineering	Describes a hardware brand or a design influence, not a place of manufacture or a performance level	Name the hardware set and the groove standard
The system is tested	A test report describes one specimen. Factory production control is what covers every unit	Does this configuration fall inside the tested specimen
Slim sightlines	Usually quotes the frame. The band you see is often the sash or the interlock	Give me frame, sash and mullion face separately
Heavy duty	An adjective until it is a number with a unit and a per-sash qualifier	Rated sash weight in kilograms, for this glass build-up
Meets international standards	There is no such single thing, and compliance is jurisdictional	Which standard, which version, which clause
Standard size	Standard to whose catalogue, and nominal or actual	Frame size in millimetres
Adjustable hardware	Everything is adjustable by some amount. The amount is the whole question	Published adjustment travel in millimetres, per direction
Spare parts available	Hardware is often cross-sourced. Profiles, gaskets and beads are not	Which parts ship in the original container, and which need our order number

What We Can and Cannot Do for a Designer

We can	We cannot
Issue section drawings that show all seven zones, so the review is about facts rather than adjectives	Cut a die for one project's elevation at ordinary project volumes. The economics of tooling do not work that way, and we will say so early
Produce a fabrication set that interprets your design and flags every departure for approval	Carry the design responsibility or seal the deepening design in your jurisdiction
Name the hardware platform, groove standard and fastener material as separate order lines	Tell you the design pressure of your building. That comes from your engineer and your code
Hold one coating batch across a phased delivery and record batch numbers against opening references	Be the applicant for a local product approval, or transfer a test report to your project by assertion
Say plainly when a category in our catalogue is empty or a page is a placeholder	Substitute a sliding door where a swing door was specified, and call it equivalent
Confirm glass and sash weight against the published rating for your configuration	Guarantee a maximum panel size independently of the glass you choose

Six Questions Designers Actually Ask

Can you design a section for my project

Almost certainly not, and you should be suspicious of anyone who says yes quickly. A new section means a new die, a trial extrusion, at least one correction round and a minimum quantity denominated in hundreds of kilograms or tonnes of that one profile. What we can do is show you the sections that exist, explain what each one is already solving, and let you choose with your eyes open. The choice is real; the design is not.

Then what am I actually designing

Subdivision, visible bands, colour, opening method, glass build-up, threshold condition and the performance figures you write down. That is a substantial list, and it is where buildings are won or lost. It is just not the same list as the one that determines whether water gets out of the frame. When people ask what is a casement window, the answer changes with who is asking: to a designer it is an opening type with a swing path and a set of ratings to specify; to a factory it is a section, a hardware set and a cut list.

Why does the section matter more than the glass

Because glass is the one row you can still change later, and the section is the row that was fixed years ago. Published technical writing puts it directly: the glass did not change, the frame geometry did. A thermally broken head and jamb with a conductive sill is not a balanced system, and no coating on the glass repairs that.

Who is liable if the deepening design is wrong

Read your contract and your local rules, not this article. What we can say is that published regulatory instruments in China place an explicit review duty on the original design institute: it must check whether the deepening design changes the original standard or the functional requirement, seal it, and answer for what it reviewed. That is why we flag every departure rather than quietly fixing it.

Is a configurator good enough for a small project

For comparing and pricing, yes. For anything where the opening is not yet settled, the interface is unresolved, or the wall is unusual, no. The failure mode is specific and worth naming: a default value for jamb depth, carried through a whole order, produces windows that are too shallow for the wall and a site team building extension jambs. Five seconds of measurement prevents two days of carpentry.

What should I ask for first

The section drawing, before the quotation. Not the brochure section with shading, the dimensional one. It shows the drainage route, the thermal break position, the hardware pocket and the glazing rebate, which are four of the seven zones and none of which appear on an elevation or in a price. If a supplier will not produce it, that tells you something earlier than any other question you could ask. Our completed project references and a custom sun room enquiry both start the same way, with the wall and the section.

The Short Version

• The word designer covers at least six different jobs. The one who understood the section best stopped being reachable years ago.
• Design pressure belongs to the building, design awards belong to a handle, design software belongs to a vendor, and section design belongs to a die that has already been cut.
• Published instruments name the designer's window duties as subdivision, openings and writing the performance figures down. Not one word about the section.
• The manufacturer may draw the deepening design; the original design institute must seal it and answer for it. One document, two authors, one signature.
• A section solves seven problems at once. None of the seven is visible on an elevation.
• In our own catalogue: eleven published numbers decide what the building looks like, thirty-seven decide what it does. They are printed in the same columns.
• Glass is the only row you can still change. That is exactly why it is the wrong place to start.
• A configurator does not ask how thick your wall is. It assumes one.
• Ask for the dimensional section drawing before you ask for the price.
• Freeze five numbers on the same day, and name who signs. Everything else in this article is commentary on those two sentences.