ALPES Aluminum Casement Window Specification Text: Eleven Clauses, Four Words, and the Number That Is Really a Sentence

Search for casement window specification text and you will find plenty of it: a tidy paragraph about thermally broken aluminium frames, multi-point locking, double glazing and powder-coated finishes. It reads well. It is also, almost without exception, unenforceable — not because it is wrong, but because there is no sentence in it that anyone can fail.

That distinction matters more than any parameter in this article. A description tells you what a window is like. A specification is a set of sentences that a named person will later have to prove or disprove, using a named document, at a named moment. If a sentence cannot be failed, it is not a clause. It is a preference that wandered into the contract documents wearing a clause's clothes.

We make the window, so we read these documents from the receiving end. We know exactly which sentences we can answer from a catalogue and which ones send us back to a test house, a calculation, or a conversation. That asymmetry is the subject here. Below is the clause-by-clause anatomy of an aluminium casement window specification: what each part is for, which words quietly transfer risk, why a performance class is a sentence rather than a number, and the clauses that a casement window spec routinely leaves out.

A Clause Is Four Columns, Not One Sentence

Take any line you are about to write and try to complete four columns for it. If you cannot fill the last three, the first one is decoration.

Column	The question it answers	What an unfilled column looks like
The requirement itself	What must be true	"High quality hardware" — true of everything anybody is willing to ship
The verifier	Who has to demonstrate it	"The contractor" — the contractor does not make the window
The document	What piece of paper settles it	"Test reports" — of which specimen, tested to which edition
The moment	When it must exist	No date at all — so it can be answered after handover

Now write the same requirement as a clause and watch the three empty columns fill themselves. "Hardware: manufacturer's published cycle test report for the exact operator model supplied, submitted with the shop drawings, ten working days before fabrication release." Same intent. One of them can be failed on a Tuesday morning.

There is a second reason the four-column test is worth the trouble. On a project where the specification is descriptive — where it prescribes materials and methods rather than results — the design liability sits with whoever wrote the description. Under the doctrine that grew out of United States v. Spearin in United States law, an owner impliedly warrants that a contractor who builds exactly to a prescriptive specification will get a workable result. That is the trade: a descriptive clause gives you control and hands you the consequence. A performance clause gives the supplier freedom and hands them the burden. Most casement window sections mix the two without noticing which lines are which.

The Section Is Not the Product: Where a Casement Window Spec Actually Lives

In a MasterFormat-style project manual, aluminium windows sit in Division 08 (Openings), section 08 51 13 Aluminum Windows, written in the three-part SectionFormat: Part 1 General (scope, references, submittals, quality assurance, delivery and storage, warranty), Part 2 Products (materials, fabrication, finishes, hardware, accessories), and Part 3 Execution (examination, preparation, installation, field quality control, adjustment, cleaning, protection). Division 01 General Requirements sits above every technical section and governs the administrative procedures that all of them must follow.

The interesting part is not the three parts. It is the related-sections list, because that list is where casement window failures actually live.

Related section	What it owns	Why the window section cannot fix it
08 80 00 Glazing	The glass make-up, coating, spacer, gas fill	"Double glazed" in 08 51 13 with a different spec in 08 80 00 is two answers to one question
07 92 00 Joint Sealants	The perimeter seal between frame and wall	Most "the window leaks" claims are this line, and it is in Division 07
07 60 00 Flashing and Sheet Metal	Head flashing, sill pan, the path water takes out	A perfect window in an unflashed opening is a wet window
07 27 00 Air Barriers	Continuity of the air line around the opening	Air leakage measured on site is usually the joint, not the sash
09 06 00 Schedule for Finishes	Colour and coating designation	Naming a colour in two places invites two batches
05 50 00 Metal Fabrications	Steel subframes and reinforcing	A subframe can bridge the thermal break the window was bought for

The practical consequence: a casement window specification can be fully compliant and the installed window can still leak, because the two documents that decide whether it leaks are not the document titled "Aluminum Windows". When you write or review the section, read the four related sections at the same sitting. And note the drafting convention that governs all of them — drawings show quantity, location and configuration; specifications state quality, material and workmanship. Quality requirements written onto a drawing become a conflict the moment the specification is revised.

One more structural note. A clause set written for one product family does not travel. The clauses you would hand to an aluminum alloy folding door wholesaler — panel stacking, top-hung load paths, folding stack clearance — are not the clauses you hand to a casement supplier, where the load path runs through hinges and a frame that has to resist racking. If you maintain a master specification, keep one section per operating type and resist the urge to merge them.

Four Ways to Write a Clause, and Who Carries Each One

There are four recognised methods of specifying, and a good casement window section uses all four in different lines. The mistake is not picking the wrong one — it is not noticing which one you picked.

Method	What it does	Where the risk lands	How it fails in a casement section
Descriptive	States properties, dimensions and workmanship; names no brand	Stays with the specifier	You have now designed the window. If it flexes, the description was yours
Reference standard	Cites a published standard by designation	Shared, but you own the citation	"Complies with GB/T 8478" imports every table in it, including the ones you never read
Performance	States the required result and how compliance is verified	Moves to the supplier or fabricator	Only works if you also define the specimen — otherwise every bidder tests a different window
Proprietary	Names manufacturer, brand, model	Shared once you add "or approved equal"	"Or approved equal" with no criteria is the sentence that buys the worst acceptable window

Two of these deserve a closer look because they cause the most damage in window sections specifically.

The reference standard you cited is longer than you think

The standard drafting position on reference standards is blunt: provisions incorporated by reference "become a part of the specifications just as though included in their entirety." So when a section says the windows shall comply with a national aluminium window standard, it has just adopted that standard's scope, its classification tables, its tolerances, its test sequences and its sampling rules — including the parts nobody on the design team opened.

That is fine, provided you do two things. First, name the edition. Standards are revised, and the revised version usually moves the numbers. Publicly circulating summaries of one widely used Chinese test method give the same edition's top air-permeability band at two different values, which is a useful reminder: if the popular tables disagree, the only defensible source is the standard text plus the report. Second, name the class, not the standard. A standard contains levels. Citing the document without the level is not a requirement; it is a reading list.

"Or approved equal" is only as good as the word "equal"

The open proprietary method — naming a product and allowing substitutions — is standard practice and, on many public projects, a competitive-bidding requirement. It works when the substitution clause lists what a substitute must demonstrate. It fails when it does not, because "equal" then means whatever the person under schedule pressure decides it means that week.

The fix is a single sentence appended to the named product: substitutions considered only where the requesting party submits, before bid, documented evidence of compliance with each performance requirement listed in this section. That turns a comparison of brochures into a comparison of documents. A related and often better option is the basis-of-design approach: the named product sets the benchmark, and any alternative must measure up to it in measurable terms. That only works if the benchmark product's data is itself measurable — which brings us to the largest gap in most casement window sections.

Four Words That Decide Who Pays

Specification language has a small vocabulary with large consequences, and the conventions are taught consistently enough to be worth stating plainly. In the CSI Construction Specifications Practice Guide, "shall" and "will" are used as imperatives for work required of the contractor, while "will" is reserved for acts required of the owner or the architect/engineer; "must" and "is to" are not recommended. Black's Law Dictionary gives "shall" its mandatory sense: has a duty to, is required to — the sense drafters intend and courts typically uphold.

Word	Usual meaning	What happens when it appears in a window clause
Shall	Mandatory obligation on the contractor	The line is enforceable. Make sure the supplier is actually a party to it
Will	An act by the owner or the A/E	"The manufacturer will provide drawings" obliges nobody who signed the contract
Should	Advisory; no obligation attached	The single most expensive word in a specification. ｄｅｌｅｔｅ it or upgrade it
May	Permissible, at the option of the party	"Screens may be factory glazed" is not a requirement, it is a shrug

Alongside these sit a family of adjectives that specification guides tell writers to avoid outright, and they are the ones that show up most often in window sections: good workmanship, adequate, reasonable, satisfactory, generally, workmanlike, best commercial quality, standard practice. None can be measured, so none can be failed, and each one silently converts a requirement into an argument. Two more drafting habits belong in the same bin: writing "as approved", "as required" or "as directed" without naming who approves; and using "and/or", which has no definite meaning.

The positive version is short. Write in the imperative mood — "Provide", "Submit", "Test" — rather than "the contractor shall". Use streamlining: put the subject first and follow it with the requirement, as in Frame depth: 116 mm. Operator cycles: submit test report. Short lines get read; long ones get skimmed, and the skim is where disputes start.

The Class Is a Sentence, Not a Number

Here is the part of a casement window specification that is most often written wrong, and it is wrong in the same way in every market.

A performance designation looks like a short code. It is not. Read one from an actual published test report and you can see how much is packed into it: the primary designator reads Class AW – PG100 : Size tested 900 x 1500 mm – Type C, and it is accompanied by a positive design pressure, a negative design pressure, a water penetration resistance test pressure, an air infiltration level, a test completion date and a report number. The tested size is inside the designation. That is not a footnote; it is half the meaning. A second published spec section for an inswing casement carries the designation AW-PG80-C, where the trailing letter identifies the operating type.

Two consequences follow, and both belong in your section text.

First, the grade is attached to a specimen, so the specimen must be described. The guidance from the Fenestration and Glazing Industry Alliance is explicit that a manufacturer intending to certify a product in larger sizes must test the largest size it intends to certify and label. It also distinguishes a performance grade from a design pressure, precisely because products were being promoted on structural pressure alone while the other required categories went unmentioned. Clause-level translation: do not accept a pressure figure without the grade, and do not accept the grade without the size and the type.

Second, the edition lags the publication. A newer edition of the North American fenestration standard was published in 2026, while the model codes in force referenced an earlier edition. If your section cites the standard by name without a year, and your authority cites a different year, you have two specifications and one window.

The European declaration makes the same point even more sharply

Under EN 14351-1, the harmonised product standard for windows and external doorsets, the manufacturer issues a Declaration of Performance. Read one and you will see that it is a table, not a number. Each row is an opening function — the way the leaf actually opens — and each column carries a declared value, the classification standard behind it, the test standard, the notified body, the test report reference, and the tested size in millimetres.

A real declaration for a triple-glazed door product line shows the single-leaf outward-opening version declared at wind load Class C4 (1600 Pa), watertightness Class 9A (600 Pa) and air permeability Class 4, tested at 950 x 2185 mm. The two-leaf version of the same product line sits directly below it and reads NPD on all three. NPD means No Performance Determined. It is a legal status, not a failure to test — but on a tall facade it is also the honest answer to "what is the rating of the double version", and it is the answer you would never have guessed from the single-leaf figure.

So the clause you write is not "shall be Class 4". It is: air permeability shall be Class 4 to EN 12207, demonstrated by a test report to EN 1026 for the exact opening function, configuration and tested size supplied. And you need to know what the scale means to know whether Class 4 is even the right ask.

Characteristic	Scale	What the scale actually steps through
Air permeability, EN 12207	Class 1 to Class 4	Higher is tighter; Class 4 is verified up to 600 Pa under EN 1026
Watertightness, EN 12208	1A to 9A, then Exxx	Pressure in steps to 600 Pa at 9A; "A" means tested unprotected, the severe method
Wind resistance, EN 12210	Class 1 to 5, then Exxxx, with suffix A/B/C	Number is the load (Class 4 is 1600 Pa); letter is the permitted deflection, A loosest to C stiffest
Thermal transmittance	A continuous value, not a class	Computed under EN ISO 10077 or measured under NFRC; boundary conditions differ, so conversions are arithmetic, not equivalences

The Chinese framework works the same way with different labels. GB/T 7106 sets out the test methods for air permeability, watertightness and wind load resistance of external windows and doors, and the classification runs in grades rather than classes — air permeability in eight grades, watertightness in six, wind load resistance in nine, the last keyed to a P3 value. The lesson for the spec writer is identical: the grade number is meaningless without the report, and the report is meaningless without the specimen description.

One pattern is worth carrying across all three systems. Casement and tilt-turn sashes, which compress a gasket all the way around, typically land higher on air permeability than sliding sashes, which can only wipe. If your section is written around a casement window and then value-engineered into a slider, the air number in the spec is no longer the air number of the product. Write the operating type into the performance clause, not just into the schedule.

The Clauses a Casement Window Spec Leaves Out

Most published casement window specification text covers profile, glass, hardware and finish. Those are the easy four. The following are the ones that decide outcomes, and they are frequently absent.

Handing, with the viewpoint stated

"Left hand" is two different windows depending on which side of the wall you are standing on. Published casement sections that get this right define it explicitly: hinges on the left when standing outside and looking in. Without the viewpoint, the clause is a coin toss resolved at the Site, by whoever unpacks the crate. The same ambiguity is why any specification covering a left hand swing door has to fix the viewing direction before it fixes the word. Put the viewpoint in the clause. Put handing on the schedule too, per opening, not once in Part 2.

Configuration, not just type

"Casement" tells you the sash swings. It does not tell you whether the unit is vent-to-vent, vent-to-fixed, vent-under-fixed or vent-over-fixed, nor whether the mullion is integral to one master frame. Those are separate clauses with separate consequences for sightline, for structural depth and for how many lock points the unit actually gets. In our own catalogue the mullion is published as a pair of numbers — for example 75/31 on the C120, 75/21 on the C113 and 58/22 on the C116 — where the first number is depth and the second is the visible face. A clause that quotes only the second number is specifying the view and not the structure.

The two thermal break sentences almost nobody writes

Published aluminium window sections contain two sentences that do more work than any thickness figure, and they are badly under-used:

• "The thermal break shall not be compromised by hardware or metal fasteners."
• "Do not allow subsills or anchor clips to span thermal breaks and connect the separated components."

Both are enforceable on site with a screwdriver and a section drawing, which is exactly why they are worth having. A thermally broken frame fixed with a continuous steel angle across the break is a thermally broken frame that is not thermally broken.

A definition of failure

One published institutional specification defines the term that decides most window disputes: uncontrolled water is water not drained to the exterior, or water appearing on the room side of the window. Adopt something equivalent. Without it, "it leaks" is a feeling; with it, "it leaks" is a condition with a pass and a fail. Note what the definition gracefully handles: water sitting in a frame cavity that drains to the outside is doing what it was designed to do. Water on the room side is not.

Hardware, cycles and the difference between a rig and a building

Cycle figures are test-rig results, not service lives, and a handle cycled on a bench is not a loaded sash cycled in a frame. Both statements are true and both belong in the clause: ask for the report, the standard it was run to, and the configuration of the test piece. Also specify who performs the first adjustment. A multi-point casement that has never been adjusted is not a defective casement; it is an unfinished one, and the sentence allocating that task prevents a commissioning argument eighteen months later.

Screens, restrictors and the parts that move more often than the window

Where a casement window carries an integrated insect screen, the screen is a second operable leaf with its own cycle count, and it is operated every time the glass is operated. It is also frequently omitted from the hardware clause entirely. Opening limiters and fall-arrest devices belong in the same place: they are safety components, they are cheapbefore fabrication and awkward after it, and in some jurisdictions their presence is a regulatory matter rather than a preference. Check yours with the authority having jurisdiction — we will not endorse a rule for a market we do not build in.

"Identical to the windows tested"

Published institutional sections require a manufacturer's certification that the windows delivered are identical to the windows tested, and they commonly put a freshness limit on the test reports behind that certification. Whether or not you adopt those exact limits, adopt the mechanism: the delivered product must be traceable to the tested product, in writing, before release for fabrication. That one sentence converts a test report from marketing collateral into a contract document.

Field testing, and the two-thirds question

Site water testing is usually run to the AAMA 502 method, and published sections show the common practice of testing at a pressure above two-thirds of the laboratory pressure. Two things follow. The fraction is a default, not a law — a specifier can require the full laboratory value in writing, and on exposed elevations it is worth doing. And the pre-check matters as much as the test: published sections instruct that a unit outside a tolerance of roughly 3 mm out of plumb, level or square should not be tested at all, because you would then be testing the installation rather than the window. Write both sentences in.

The Text Itself: A Skeleton You Can Fill

Below is the shape of a casement window section. Every value is a blank, deliberately: the numbers belong to your project, your climate, your code edition and your tested specimen. What is not blank is the structure, the verbs and the four-column discipline.

Notice what the skeleton does with dimensions. It asks for frame depth, member thickness and thermal break width as separate blanks, because they are separate properties. A catalogue that offers "113" and "116" is offering frame depth figures; the number in a product name is a nominal call-out, in exactly the way a 36 x 80 entry door is a nominal call-out rather than a manufacturable dimension. Your order needs the manufacturable one.

Ten Clauses That Read Well and Enforce Nothing

The clause	Why nothing can fail it	The rewrite
Thermally broken aluminium	Says nothing about the material or the width of the break	Name the strip material, its width in mm, and the chamber count
High quality hardware	"Quality" is not measurable	Name the operator model, the lock point count and the cycle test report
German hardware	A country is not a grade; every brand makes several tiers	Name the brand and the specific product line, plus the report
Complies with international standards	No designation, no edition, no class	List each standard with its year and the required class or grade
Weatherproof	No pressure, no duration, no definition of failure	Define uncontrolled water, then give the test pressure and method
Double glazed	Two pieces of glass is not a specification	Give the full make-up, spacer, coating, gas fill and certification
To match existing	Existing what — and measured by whom	Attach a survey of the existing unit with dimensions and photographs
As directed by the architect	A direction given after bid is a change, not a requirement	State the requirement now, or state the date by which it will be given
Install in accordance with manufacturer's instructions	The instructions were never submitted, so nobody knows what they say	Require the instructions as a submittal, then reference the submitted revision
Or approved equal	"Equal" is undefined, so it means whatever is convenient	List the criteria a substitute must document, and the deadline for submitting them

What We Publish, and What You Still Have to Ask For

A specification is only as good as the documents that answer it. Here is the honest map for our own casement range, so you can see which of your clauses we can answer from a catalogue and which have to go back to a test house or a calculation.

Line	What we publish	What your clause still needs to say
Alloy and temper	6060-T66 on every series	Identical across the range, so it is a floor not a differentiator. Ask for a mill certificate per batch, traceable to the packaging
Wall thickness	A stated range, for example 1.8 to 2.0 mm	Name the members, state that it is measured on metal excluding coating, and say where it may be measured
Thermal break	PA66GF25, multi-chamber; a width band on some series	Require the strip width in mm for the series you are buying, not a generic material name
Thermal transmittance	K values on some series, and not on others	These are system values, not whole-window values for your opening. Ask for a calculated value at your size and glass, and name the boundary conditions
Glass sash thickness	Figures such as 62, 57 and 81 mm by series	A stack-up, not a glass rebate. Ask for the rebate dimension on the section drawing
Frame depth	Figures such as 119, 113 and 116 mm by series	Depth into the wall, not an opening dimension. Confirm it against your wall build-up
Mullion	A pair, such as 75/31, 75/21 or 58/22	First number is depth, second is the visible face. Specify both
Corrosion and shear figures	Published for one specific series only	Do not transfer them to another series, and note that neither is an air, water or wind rating
Cycle counts	A rig figure for a named hardware brand	State that it is a bench result, and name the configuration you want it demonstrated on
Air, water and wind ratings	Not published for the casement series	This is the most important line on the page. A clause naming a class requires a test we must run or a calculation we must produce. Ask before you write it

That last row is worth restating, because it is where most casement specifications quietly break. A defect is a departure from a declared threshold. Where no threshold is declared, "the window leaks" is not a measurement — it is an argument. If your project needs a rated window, say so in the enquiry and ask what has to be tested, at what size, and to which edition. We would rather be asked in week one than argue in week forty.

The Specification Is Not the Purchase Order

One last structural point, and it is the one that costs the most money. The specification lives in the contract documents. The purchase order is what a factory actually receives. They are different documents, and the gap between them is where disputes are manufactured.

• Attach the section, by number and revision date. A specification without a revision date gets answered against whatever version the estimator had open.
• Restate the performance clauses in the order. What is written into the order is a defect. What is printed in a brochure is an opinion.
• Give dimensions in millimetres, per opening. Nominal call-outs are not manufacturing dimensions.
• Name the submittals and their dates. A submittal with no date is a submittal that arrives when it is no longer useful.
• Name who signs for the first adjustment and the field test. The party holding the screwdriver on the day is rarely the party that wrote the clause.

Six Questions We Get Asked

Can you just send us your specification text?

We can send product data, section drawings and the test documents we hold. What we will not do is write your section for you, because the two sentences that matter most — the class you need and the size it has to be demonstrated at — depend on your code edition and your elevation, not on our catalogue. Take the skeleton above, fill the blanks, and send it to us with the enquiry.

Is naming a brand better than naming a performance value?

They do different jobs. A brand gives you a known geometry and a known hardware set; a performance value gives you something you can test. The strongest sections do both: name the basis of design, then list the performance requirements every substitute must document. Neither works alone.

Why does the tested size matter so much?

Because load grows with the sash. A small casement and a large one built from the same extrusions do not behave the same way under pressure — the frame, the glass, the hinges, the lock points and the anchorage all carry more. That is exactly why the tested size appears inside the designation rather than beside it, and why certifying bodies require the largest intended size to be the one tested.

Our spec says "complies with the national standard". Is that enough?

It is a start with two holes. Standard-compliance clauses import the entire document, including the classification tables, so you have adopted levels you did not choose. And without a class or grade named, there is nothing to test against. Add the edition year and the required class.

Should the glass clause sit in the window section?

Usually not. Glass is normally specified in the glazing section, and the window section references it. The failure mode is writing a glass make-up in both places and ending up with two answers. Pick one home for it, cross-reference the other, and require conflicts to be raised in writing before fabrication.

What is the single clause most worth adding?

The definition of uncontrolled water: water not drained to the exterior, or water appearing on the room side. Most window disputes are not disagreements about products; they are disagreements about what "leaks" means. Define it in Part 1 and half the arguments disappear before they start.

The Short Version

1. A clause is four columns: requirement, verifier, document, moment. Three empty columns means it is not a clause.
2. Aluminium windows live in 08 51 13, in three parts, under Division 01. The leaks usually live in Division 07.
3. Know which of the four methods each line uses. Descriptive keeps the design liability; performance moves it.
4. "Should" assigns no responsibility. "As approved" without a named approver is not a requirement. ｄｅｌｅｔｅ both.
5. A class is a sentence: value, standard and edition, opening function, tested size, report number.
6. NPD is a legal status, not a failure. And the two-leaf version of a rated product can be NPD.
7. Write the thermal break integrity clause. It is enforceable with a screwdriver.
8. State handing with the viewpoint. "Left hand" from outside and from inside are two windows.
9. Require a certificate that what is delivered is what was tested.
10. Screens, limiters and fall-arrest devices are spec items, not accessories.
11. Attach the section to the order, by number and revision date, with dimensions in millimetres.
12. If no threshold is declared, nothing can be measured — and every complaint becomes a negotiation.