We have already written about whether a sliding window can be made big enough to qualify as an escape opening at all. This piece starts where that one stops. Assume the hole is large enough. The question is no longer about millimetres of glass; it is about which piece of metal you are allowed to screw onto the panel that moves, and what that piece of metal is allowed to do to the opening it guards.
Two words in the title are doing more work than they appear to be doing. Vent is not ventilation. It is the trade name for a panel. And latch types turns out to contain at least two objects that look nearly identical on a shelf, are sold in the same packaging, are operated with the same hand, and are regulated in opposite directions. One of them is named in a published technical bulletin as a thing it is not.
Ask a homeowner what a vent is and you will hear about airflow. Ask the standard that defines fenestration products in North America and you will hear about a part. In ANSI/NFRC 100 the definition of an individual product lists what makes a product one product and not another: weather seals, glazing method, hardware, operable and non-operable configurations, ventilators, weep systems and sills. A ventilator sits in that sentence between the hardware and the weep holes. It is a component, in the same grammatical position as a gasket and a drainage slot.
The same document uses the word again in the naming of configurations, and there it is unmistakably a noun for a panel. The naming system itself is worth having in front of you, because it decides the latch question before anyone has chosen a latch.
| Configuration | Letters | Panels that move | What the vent closes against |
|---|---|---|---|
| Single slider | XO or OX | One | The frame jamb |
| Picture slide, also called end vent | XOX | Two, one at each end | The frame jamb on each side |
| Centre slide | OXO | One, in the middle | The stile of a fixed panel |
| Bi-part centre slide | OXXO | Two, meeting in the middle | The other moving panel |
| Double slide | XX or XXO | Two, bypassing each other | The other moving panel |
| Double slide and vent | XXX | Three | A moving panel for two of them |
The word vent appears twice in that list of six names, and in both cases it is attached to a panel rather than to a draught. In retail language the same habit survives as a unit of measure: a slider whose sash fills half the frame is called a half vent, and one whose sash is narrower than half is called a single vent. Vent is the fraction of your opening that is allowed to move.
There is a live disagreement sitting inside that table, and it is worth seeing rather than smoothing over. ANSI/NFRC 100 defines an XX double slide as a unit where adjacent sashes bypass one another. A published aluminium window guide aimed at another market states flatly that you cannot put two operable panels next to each other, because a sliding panel needs a fixed panel to travel past. Both statements are correct inside the system that produced them. Neither tells you what your particular extrusion will do. Ask for the drawing.
Every latch has two halves. One half moves with the vent; the other half, the keeper or strike, sits on whatever the vent arrives at. This is the step most latch guides skip entirely, and it is the step that decides whether a latch that works beautifully on a sample will still work on a building.
| The keeper is mounted on | Whose tolerances accumulate | What drifts over time | What goes in the order |
|---|---|---|---|
| A frame jamb (XO, OX, XOX) | The frame and the vent only. The frame is anchored to the wall and does not travel. | Roller height and track wear on the vent; seal compression; building movement | Keeper height relative to the sash, and the adjustment range written as a number |
| A fixed panel (OXO) | The frame, the fixed panel and the vent. The middle term is fixed, so it contributes once and then stops. | The same, plus how square the fixed panel was glazed | Whether the keeper lands on a stile or on a glazing bead. Never on a bead. |
| Another moving vent (OXXO, XX) | Both vents, both sets of rollers, both tracks, and the interlock geometry between them | Everything above, twice, plus where the last person stopped pushing | The interlock section drawing, and the closing sequence: which vent is latched first |
Read that table from the top down and you are reading a ranking of how much of the tolerance budget you own. A keeper screwed to a frame jamb is screwed to something the building holds still. A keeper screwed to another panel that also rolls is screwed to something whose resting place depends on roller adjustment, track condition and the force of the last person to close it. The same latch has two different tolerance budgets depending on which configuration it is fitted to, and nothing on the packaging says so.
It is worth putting the alternative next to it. A 24x40 casement window closes against frame on all four sides and pulls into it with a multipoint mechanism; the reaction to every lock point is the frame, and the frame is anchored to the wall. A sliding vent of the same nominal size meets something on one vertical edge. That is the whole difference, and it is a difference in what the latch is allowed to push against, not in how expensive the latch is.
Our own sliding window catalogue is published in two configurations only: one fixed with one movable, and a middle fixed with two movable sides. Both of those put every vent against a frame jamb. We do not publish a bi-parting configuration in which two vents meet each other, which means the hardest row of that table is a row our own sliding window range does not occupy. We would rather say that than let you discover it on site.
Published latch guides tend to arrange the field by security level or by ease of use, which are the two things a buyer already has an opinion about. One hardware technical page puts the problem better than any buyer guide we have found. Crescent locks, cam locks and sash locks overlap as labels, the page says, and then adds the line that should be printed on every latch box: the labels overlap, the dimensions do not.
The column that actually decides behaviour is not security level. It is whether the device blocks motion or pulls the vent into something. Some cam locks merely stop the sash from sliding. Others apply compression. Only the second kind does anything for the seal, and both are sold as cam locks.
| Latch family | What it does when it closes | Blocks or pulls | What it quietly assumes | What it is not |
|---|---|---|---|---|
| Surface slide bolt or barrel latch | A bolt travels into a catch or a hole in the track or the meeting stile | Blocks only | That someone will remember to throw it, and that the hole is still where the hole was | Not a seal. Not a fall device. |
| Sweep or crescent sash lock | A curved arm rotates into a keeper and, if the geometry is right, draws the two members together | Pulls, when the geometry is right | That the keeper height, the sweep radius and the sash overlap were designed together rather than matched by eye | Not automatically secure. A sweep engaged only at its tip looks closed and resists nothing. |
| Cam latch | An eccentric rotating element engages behind a keeper, a strike or a frame edge | Either. This is the family where the two behaviours are most often confused. | That the shaft is supported and the keeper is reinforced, not sheet-thin | Not a security grade. Keyed quarter-turn cams exist for cabinets and enclosures too. |
| Keyed sash lock or cylinder lock | Any of the above with a cylinder in front of it | Whichever the underlying mechanism does | That the key has a home. The key is now part of the building, not part of the window. | Not a reason to fail an escape opening by itself. The test is the release, not the cylinder. |
| Push latch or press-release catch | Engages on a press, releases on a press | Blocks | That nobody leans on it. A press release is also a press open. | Not a child-resistant mechanism in the sense used by fall-prevention rules |
| Interlock or meeting-stile latch | A hook or cam on one vent engages a keeper on the vent it meets | Usually blocks, sometimes pulls the two vents toward each other | That the other vent is where it was when the drawing was made | Not a frame anchor. It cannot borrow stiffness from the wall. |
| Multipoint espagnolette with transmission | A handle drives rods and cams that engage keepers along the sash edge | Pulls along the whole edge | That the sash is stiff enough to distribute the pull, and that every cam was adjusted | Not a point count equals security argument. Spacing and adjustment decide it. |
| Vent stop or night latch | Holds the vent at a small fixed opening so air comes in and hands do not | Blocks, deliberately, at a distance | That nobody will ever need that opening for anything larger | Not a fall prevention device. Named as such in a published bulletin. |
| Window opening control device | Limits travel to below a stated sphere, releases on a defined action, and re-arms itself when the sash closes | Blocks at a distance, then gets out of the way completely | That the sash it was tested on is the sash you have | Not a lock, not a vent stop, and not interchangeable with either |
The last two rows of that table are the reason this article exists. They are sold near each other. They are fitted near each other. On a sliding window they can occupy the same top rail. And one of them is written out of the other's category by name.
A joint technical bulletin published by two window industry bodies exists for the single purpose of explaining what a window opening control device is. It lists the operational requirements, and then it does something unusual: it names the impostor.
Read that slowly, because it is the most useful paragraph published about this subject. A vent stop is named after the vent. It is a latch-shaped object that holds the vent partway open. It is offered on exactly the product this article is about. And the standard that governs fall prevention singles it out, by name, as a thing it is not.
The bulletin also closes the loophole that a clever installer might find. The operation of the sash has to be independent of the disengagement of the control device. Operating the window cannot be counted as one of the two actions that release it. Turning the handle is not a step; it is the thing being prevented.
| Question | Vent stop or night latch | Window opening control device |
|---|---|---|
| What is it for | Ventilation while discouraging entry | Reducing accidental falls while keeping the escape route available |
| Does it limit travel | Yes, but to a distance nobody has certified against a sphere | Yes, below a stated sphere dimension, and tested to a static load and to cycle testing |
| Does it release | Sometimes. Many are fixed, and the bulletin addresses exactly those. | It must, by two independent single actions or one dual action |
| What happens after release | Usually nothing is specified | The sash must be able to open fully |
| Does it re-arm itself | Only if you remember to set it again | It must reset when the sash is closed |
| Is it allowed on an escape window | Not if it cannot be released and it stops the sash short of full opening | Yes, and that is the point of the category |
Four operational requirements, quoted from the industry bulletin, plus two instructions from a manufacturer's own safety sheet for a real device. Nothing here is our opinion and nothing here is our product.
| Requirement | What it means on a sliding vent | Where it is easy to fail |
|---|---|---|
| Limit the sash opening to less than four inches, the dimension universally used in building codes for guardrail openings | Four inches of linear travel, measured so that a rigid sphere of four inches, published by one manufacturer as one hundred and two millimetres, cannot pass at the lowest part of the opening | The gap at the bottom of a sliding vent is not always the gap you measured. It grows as the sash rises on its rollers. |
| Be releasable by two independent single-action devices, or by one dual-action device | Two things have to be done, and they have to be two things, not one thing done twice as hard | Fitting one release and calling the slide itself the second action. The bulletin forecloses that. |
| After release, allow the sash to open fully | The escape route is the whole travel of the vent, not the restricted travel | A stop in the track that has to be unscrewed to be bypassed. That is a tool. |
| Reset automatically when the sash is closed | The next time the vent is opened it is limited again, without anyone remembering | A sash that stops a few millimetres short of closed never passes the reset point, so the device quietly stops working |
The manufacturer's safety sheet for one tested device adds two instructions that a specification rarely captures. Both release devices on the sash have to be worked to get the window open for escape. And the release must never have a padlock or any device requiring a key or a tool applied to it. That sheet also asks that the release be tested regularly and that everyone in the household who is old enough to understand it be shown how it works, and it notes that these devices are limited to certain product configurations with a maximum sash size.
That last sentence is the one that should change how you write an enquiry. A tested device covers a tested sash, not a series name and not a catalogue. If you have not told anyone how big your vent is, nobody can tell you whether a device covers it.
Now compare the North American route with the Australian one. Both are trying to stop a small child from going out of a window. They measure different things, they pick different numbers, and on the single question of whether a key may be part of the answer they disagree outright.
| Item | United States route | Australian route |
|---|---|---|
| How high before it matters | The opening is more than seventy-two inches above the grade or other surface below, on the outside | The floor level beneath the window is two metres or more above the surface beneath |
| The second measurement | The bottom of the opening is less than twenty-four inches above the finished floor inside a house, or less than thirty-six inches in residential occupancies the building code calls R-2 and R-3 | The lowest part of the opening is less than 1.7 metres above the floor. At or above that, no protection is required. |
| The child | A rigid sphere of four inches, published by one manufacturer as one hundred and two millimetres | A sphere of 125 millimetres |
| The force | The standard includes a static load and cycle testing; ask for the report rather than a summary | An outward horizontal action of 250 newtons, against the restrained sash or against a screen |
| The release | Must be possible without a key, a tool or special knowledge. The manufacturer's sheet forbids a padlock or keyed device on the release. | If the device can be removed, unlocked or overridden, the release must be child resistant, and the advisory note lists a key, a coordinated two-handed operation, or a tool such as a screwdriver, spanner or Allen key |
| What you must also build | Nothing extra, provided the device meets the standard and resets | A barrier not less than 865 millimetres high if the device can be released, unless the device is a fixture that cannot be unlocked or overridden |
| Does this hurt ventilation compliance | Not addressed in the material quoted here | No. The advisory note answers the objection directly: the window is not required to be always fully open, and the five percent ventilating area provision is unaffected. |
| Where the rule bites hardest | A window that is both the escape opening and above the fall trigger. The two rules are reconciled only by a tested device. | Bedrooms. The window protection provisions are written around the bedroom case. |
One of these documents says a key on the release is forbidden. The other lists a key as one of the three ways to make the release acceptable. They are not two drafts of the same rule. They are two different theories about who is standing at the window at two in the morning, and about which failure is worse.
The sphere is worth a second look too. One hundred and two millimetres and one hundred and twenty-five millimetres differ by roughly twenty-three millimetres. Neither number is a measurement of children. Each is a decision about what to measure, taken by a different committee, and the difference is bigger than several of the tolerances this industry argues about. Do not carry a sphere size across a border in your head.
This is the part that is genuinely surprising, and it is the part that puts a sliding window lock at the centre of a child safety rule. The advisory note published by the Australian Building Codes Board does not merely tolerate a lock as a fall device. It names it as a solution.
So the same object — a keyed sliding window lock that holds the vent at a small opening and lets it go all the way when you turn the key — is the named compliance path in one country and is precisely the arrangement the North American manufacturer's sheet tells you never to create. Both positions are internally consistent. Neither travels.
The Australian route also prices releasability. If you want a device you can override, you must put a barrier under the window as well.
| What you fit | Is a barrier also required | What it costs you in use | What people get wrong |
|---|---|---|---|
| A fixed device that cannot be unlocked or overridden without something like a drill | No. It is treated as a fixture and no child resistant release is involved. | The vent never opens fully again, on any occasion, including cleaning | Fitting it to a window that is also the escape route. That is a decision, not a device. |
| A device with a child resistant release: a key, a coordinated two-handed action, or a tool | Yes. A barrier at least 865 millimetres high, which must itself not pass a 125 millimetre sphere and must have no horizontal climbing elements between 150 and 760 millimetres above the floor. | A key or a tool now has a home, and the home has to survive a change of tenant | Assuming the barrier is optional. It is the price, not the bonus. |
| Nothing, because the lowest part of the opening is at least 1.7 metres above the floor | No protection is required at all | Nothing, and this is the cheapest compliance route there is | Measuring to the sill rather than to the lowest part of the opening that can actually open |
The third row is the one that saves money and is the one nobody asks about first. The cheapest way to satisfy a fall prevention rule is usually to move the window up, not to add a device to it. That option only exists while the wall is still a decision.
Look at a real product built for this job on residential aluminium sliders in multi-storey buildings. It is keyed. It is adjustable. It installs into the top rail of the sliding window. The installer sets the restricted distance during fitment, typically somewhere between one hundred and one hundred and twenty-five millimetres. A key-operated removable body can be separated from the window entirely for escape and for cleaning, without tools. It is offered against the national construction code provisions, against a child safety standard, and against a corrosion standard for hardware.
Three consequences follow, and none of them are obvious from a latch catalogue.
There is a fourth consequence specific to a side-pressure sliding window, and we would rather raise it than leave you to find it. Our sliding window is described as a combination of push-pull and swing hinges with an eight-point lock. A travel limiter stops the vent at a distance. Whether that distance is reached before or after the point at which the locking mechanism has to engage is a question for the hardware supplier and the sash drawing. It should be answered in writing before the device is specified, not discovered the first time somebody tries to close the window.
A hardware technical page we keep coming back to makes the point with unusual bluntness. Ordering a quantity of black sash locks without a dimensional drawing, it says, is not a specification; it is a gamble. Then it gives the reason, and the reason is a single number: a keeper that sits two millimetres too low may still catch during a polite sample test, and then fail to pull the members together once production tolerances, paint thickness and frame movement have all arrived.
Two millimetres. That is the entire budget, and it is consumed by things that have nothing to do with the latch.
| Number | Why it bites |
|---|---|
| Fixing-hole centres | The only number that decides whether the old holes can be reused, and the most common reason a replacement does not fit |
| Base length, width and height | Decides whether the body sits on a stile or overhangs it, and whether it fouls the screen track |
| Keeper dimensions | The other half of the device, and the half that is almost never quoted in an enquiry |
| Sash overlap | How much material the two members share when closed. Reduce it and the pull-in has nothing to pull against. |
| Sweep or hook projection | The difference between full engagement and a tip that looks engaged |
| Handing, where it applies | Which side of the vent the body sits on, read from outside. Ties directly to whether your unit is XO or OX. |
| Locked and unlocked handle positions | The cheapest safety feature there is. A latch that does not look locked gets reported as broken. |
| Fastener diameter | Decides what the screw holds into, and whether the hole can be re-used after one correction |
| Required substrate | On an aluminium vent the screw goes into a hollow extrusion, not into timber. Ask what wall thickness and what screw port the profile gives it. |
| Finish system and corrosion expectation | The latch is the most touched part of the window and the first to show it. Our published corrosion figure belongs to a different product and does not travel. |
| Adjustment range, written as a number | The single best predictor of whether the vent will still latch properly after the building has settled |
| Symptom | Most likely cause | What people do instead | The right first move |
|---|---|---|---|
| The latch will not catch the keeper at all | Keeper height, or a vent that has dropped on worn rollers | Filing the hook down until it goes in | Measure the ｄｒｏｐ, adjust the rollers, then set the keeper. Filing removes the pull-in you were trying to get. |
| It catches and then pops open in wind | Engagement at the tip only. The geometry blocks but does not pull. | Fitting a physically bigger latch | Correct the keeper position so the full sweep or cam engages. Size was never the problem. |
| Closed and locked, and it still rattles | A latch that only blocks motion cannot compress a seal | Adding a second latch of the same kind | A mechanism with pull-in, or an adjustment of the one you have. Two blocking latches still block. |
| The vent will not open past a short distance | A limiting device is engaged, or has re-armed | Forcing the sash and bending the stop | Work the release exactly as the instructions describe, and show everyone who might need it. A bent stop is no longer a tested device. |
| The key for the restrictor has gone missing | The key is the compliance mechanism, and it was never entered into a handover file | Drilling it out | Record the keying system at handover. A device that was drilled out is not a compliance device any more, whatever it looks like. |
| The limiter never re-arms after the window has been open | The sash is not closing fully enough to pass the reset point | Assuming the device is faulty and replacing it | Check that the vent closes completely. A sash that stops short never re-arms the device, and the new one will behave identically. |
A single opening can be asked to be several incompatible things. Write the list down before you choose a latch, because the list, not the latch, is what decides it. A below-grade habitable room is the hardest case: a tilt and turn basement window and a sliding vent are both being asked to serve as an escape route, and only one of them gets its own frame out of the opening when it is fully open.
| The window is | It must allow | It must prevent | Who decides, and when it becomes unchangeable |
|---|---|---|---|
| The required escape opening for a bedroom | Full travel of the vent, from inside, without a key, a tool or special knowledge | Nothing that stays in the opening when it is needed | The authority having jurisdiction. Fixed when the room is designated, not when the window is ordered. |
| Above the fall prevention trigger | Enough travel to ventilate, which every rule quoted here explicitly preserves | Passage of the stated sphere, at the lowest part of the opening | Two measurements, one outside and one inside. Both are set by the building, not by the window. |
| Both of the above at once | Full travel on demand, released by the defined action | Anything smaller than a tested device, and anything untested that looks like one | This is the case where a vent stop on an escape window becomes a documented problem rather than a preference |
| Ventilation only, with no code role | Whatever the occupant wants, including a wide open vent | Nothing in particular | The occupant, until the room's use changes. A study that becomes a bedroom inherits the first row. |
| In a rental or multi-occupancy building | A release that a new tenant can be shown, and a record that it was | Drift into a state where the device is present but nobody knows how it works | The manager. Fixed at each change of occupancy, which is the moment it is most often missed. |
| In a childcare, school or aged care setting | Ventilation, and release by a person who is not the person at risk | An opening that a resident or a child can create alone | The duty of care, which applies on the ground floor too. Storey height is not the trigger here. |
| Only ever opened for cleaning | Full travel, including the sash coming out of the frame on some systems | Nothing | Whoever plans the cleaning. This is where a top-rail device quietly changes the method. |
This is the section where a supplier usually lists its latch features. We would rather list what each published number measures, including the places where the answer is a different property from the one you wanted. On a tcp sliding window as much as on a made-to-measure unit, the naming tells you which panel moves; it says nothing about what is allowed to hold it.
| What we publish | What it measures | What it is not |
|---|---|---|
| Eight-point locking on the side-pressure sliding window, running German hardware for side-pressure windows and doors | How many places the vent is pulled to the frame when the mechanism is worked | Not a security grade, not a cycle count, and not a fall prevention classification |
| Multi-point locking with stainless steel locks in precision-cast reinforced casings, on one sliding door series | The material and the housing of the lock bodies, and that there are several of them | Not a statement about the keeps, the fasteners or the adjustment range |
| Transmission box and anti-pry lock points on an outward opening window | That the drive is geared and that some points are shaped to resist leverage | Not a test result, and not a claim about the sliding window, which is a different mechanism |
| CMECH hardware on an outward casement, tested to thirty thousand cycles, and a Red Dot design award | A bench test of a handle on one product, and an industrial design award | Not a service life, not a latch test, and above all not a fall prevention classification. The award belongs to the handle's design, not to the window's. |
| Two hundred kilogram load-bearing pulleys on the sliding window, two hundred and twenty kilogram single sash driving capacity on one door, four hundred kilograms on a twenty wheel self-balancing carriage on another | Three different properties, each on the product where it is printed | Not one ranking. Putting those three in a descending column is the single most common way our catalogue gets misread. |
| Two hundred and forty hour salt spray and five thousand newton shear resistance | A coating and substrate result, and the composite bond between the insulation strip and the aluminium, both on the passive window series | Not a latch test, not a corrosion figure for hardware, and not transferable to another series |
| Anti-theft grille and inward opening mesh as extended functions | Options that add a second layer in the opening | Not accessories, if this is an escape window. Anything in the opening inherits the release requirement. |
| Two production centres, and hardware from named German and international partners | Where the window is assembled, and whose mechanism is in it | Not an answer to whether a particular safety device has been tested on a particular sash. It has not, by us. |
And the sentence that matters most in this article: nothing we publish carries a window fall prevention classification. We do not offer a device tested to ASTM F2090, and we do not claim the Australian child safety standard for any product. If your project needs one, it will come from a specialist, it will be rated for a tested sash configuration, and the honest time to find that out is before the sash is built rather than after it is glazed.
| Item | Our position | Why the gap exists |
|---|---|---|
| Latch and keeper dimensions | Ask for the hardware drawing | The mechanism is our partner's, and the drawing is theirs |
| Cycle count for the sliding window lock | Not published by us | The figure we do publish belongs to a handle on a different product, and it is a bench result rather than a service life |
| Static load or forced entry class for any latch | Not published by us | We have not had one declared, and we would rather say that than imply one |
| Fall prevention classification for any device | We do not offer one | The certificate belongs to the device maker and is tied to a tested sash, not to a series name |
| Maximum sash width and height for the sliding window | Not published | It is a function of the glass configuration and the hardware, so a single number would be misleading |
| Screw bite and substrate for latch fixings on an aluminium vent | Ask for the profile section | Wall thickness is published for the profile; what the fastener actually engages is a section detail |
| Adjustment range of each locking point | Ask the hardware supplier, in writing | It is the most useful number in the whole assembly and the least often printed |
| Whether a travel limiter interferes with the locking sequence | Must be answered before the device is specified | It depends on where in the travel the mechanism has to engage, which is a drawing question |
| Which configurations the sliding window is offered in | One fixed with one movable, and a middle fixed with two movable sides | Both put every vent against a frame jamb. We do not publish a bi-parting configuration. |
| Whether your project's fall device will cover your sash | We cannot answer it from a catalogue | Devices are limited to tested configurations with a maximum sash size. Give us your sash size and we can at least tell you whether the question has an answer. |
| Line | Fill in | If it is left blank |
|---|---|---|
| Configuration, read from outside | XO / OX / XOX / other: ____ | Somebody guesses, and the handing of the latch is decided by the guess |
| What each vent closes against | Frame jamb / fixed panel / another vent: ____ | The tolerance budget is assumed to be the easy one |
| Is this vent the required escape opening | Yes / No / not yet decided: ____ | A vent stop may be supplied to a window that must not have one |
| Height of the lowest part of the opening above the finished floor | ____ mm | The interior half of the fall trigger cannot be evaluated by anyone |
| Floor level relative to the surface beneath, outside | ____ mm, and what the surface is: ____ | The exterior half of the same trigger goes unanswered |
| Jurisdiction and code edition | ____ | The key question is answered from the wrong rule book, and the two answers are opposites |
| Sphere dimension that applies, and who told you | ____ mm, from: ____ | A number crosses a border in someone's memory |
| Restricted opening distance required, and who sets it | ____ mm, set by: ____ | It gets set on site by whoever is holding the tape, with no record |
| Is a barrier also being provided under the window | Yes, height ____ mm / No / not applicable: ____ | In one of the two systems, a releasable device without a barrier is not a complete answer |
| Latch family wanted, and whether it must pull or only block | ____ | You receive a blocking device and then report a sealing problem |
| Keeper drawing, with dimensions | Requested / received: ____ | Two millimetres of disagreement arrives with the building instead of with the sample |
| Who signs for the fall device, and who is first responder | ____ | The window supplier, the device supplier and the installer each assume it was one of the others |
| Question | An answer that carries nothing | What you were actually asking |
|---|---|---|
| Is it child safe | It has a child lock | Which standard, which edition, and what sash size was tested |
| Can it be locked partway open | Yes, it has a ventilation position | You have just described a vent stop. Is this an escape window? |
| Does it meet the standard | It meets international standards | A number and a year. No number and no year means an adjective. |
| How strong is the lock | It is heavy duty | A static load figure, a cycle figure, and the standard each was run to |
| Will it fit my window | It fits our whole sliding range | Then it is sized by the worst sash in the range, which is not information about yours |
| Is it corrosion resistant | It is stainless steel | Which parts. The keep, the fasteners and the spring are not always the same material as the face. |
| Can I get it keyed | Yes, keyed alike across the project | In one system the key is the compliance mechanism; in the other it is forbidden on the release. Which one is yours? |
| Is it adjustable | Fully adjustable | In millimetres, in which direction, and with what tool |
| Is it rated for escape | Yes, it opens fully | Opens fully after which actions, and is one of them allowed to be the act of sliding |
| Who certifies the opening | The window is certified | Nobody certifies an opening. A device is tested, a window is declared, and a building is approved by somebody local. |
It is the panel that moves. In the standard that defines fenestration product types, a two panel unit with one operable sash is a single slider, written XO or OX, and a three panel unit with two operable sashes either side of a fixed centre is called a picture slide or an end vent. The slot that lets air in is a consequence of a vent existing, not the definition of the word.
One is a convenience and one is a tested safety article, and the industry bulletin is unusually direct about it. A vent stop exists to give ventilation while discouraging entry. A control device limits travel below a stated sphere, releases by two independent single actions or one dual action, allows the sash to open fully once released, and resets itself when the sash closes. It also has to be tested, including to a static load and to cycle testing. A vent stop does none of that and should not be mistaken for it.
Sometimes, and the answer depends on where you are, which is the point. In the Australian material quoted above, a keyed sliding window lock that holds the sash so a 125 millimetre sphere cannot pass but lets it open fully when unlocked is named as meeting the requirement, and a key is listed as one of the ways a release can be child resistant. In the North American material, the manufacturer's safety sheet for a tested device says never to apply a padlock or any device needing a key or a tool to the release. Both cannot be true for the same building.
Nine times out of ten it is a height problem, and the height moved because the vent dropped on its rollers or the frame moved, not because the latch wore out. The published guidance puts the tolerance at around two millimetres before a device that catches politely on a sample stops pulling the members together on a building. Filing the hook is the wrong move, because the part you remove is the part that was going to do the pulling.
You need a latch on every vent, and they are usually the same part, but they are not doing the same job if the units are not the same. In an XOX arrangement both vents close against a frame jamb. In an arrangement where two vents meet each other, the keeper of one is mounted on the other, and that keeper's position now depends on a second set of rollers and a second track. Ask for the interlock section before you assume the two are interchangeable.
No, and we would rather say it now than after the sashes are built. Nothing in our published range carries a window fall prevention classification, and a device of that kind is tested against a specific sash configuration with a maximum sash size. What we can do is give you the sash section drawing and the profile details your device supplier will ask for, so that the device is chosen against the real panel rather than against a series name. You can see the kinds of building our products go into on the ALPES projects page, but the approval for any safety device belongs to your authority and your device supplier, not to us.
| Situation | Why it goes wrong on a slider | What to do instead |
|---|---|---|
| You want a locked partway open position on a window that is also the escape route | That is a vent stop, and the bulletin addresses it by name | Use a tested control device on that opening, or move the ventilation role to a window that has none |
| You need a releasable fall device in the Australian reading and you cannot build a barrier under the window | Then the device has to be a fixture, and the vent will never open fully again | Decide which of the two you actually need before the window is ordered, not after it is glazed |
| Two vents meet each other and you need tested geometry | The keeper lives on a moving panel, and we do not publish that configuration in our sliding window range | Get the interlock section drawn and dimensioned, or choose a configuration where the vent meets frame |
| You want one latch type and one fall device across every window on the project | The latch is sized by the worst sash and the device by the tested sash, and those are different pieces of information | Group the openings by vent size and by what each vent closes against, then specify per group |
| A coastal or poolside elevation with a keyed restrictor | The cylinder becomes the maintenance item, and our published corrosion figure belongs to another product and another property | Specify the cylinder and the keying system as their own line, with a maintenance interval in the handover file |
| You are replacing a latch on an existing window and the old one has no brand on it | Two millimetres of keeper height will defeat any part that looks right | Measure and photograph the fixing centres, the base and the keeper before ordering anything |
