Every window on the market has a feature list. They are all true, they are all short, and they are all written the same way: a noun, a dash, a benefit. The problem with a feature list is not that it lies. It is that each line is a conditional promise, and the condition is not printed next to it.
The TS130 side press window has eight published features. This article takes all eight seriously and then asks the question the list does not ask: what does each one sit on? What has to be true for it to be true? And what quietly removes it?
We have already written about the TS130’s dimensions and how to size one. This piece starts where that one ended. It is about the mechanism, not the tape measure.
Here is the published list, with the dependency added in the right-hand column. That column is the article.
| Published feature | It is true only if |
|---|---|
| Combination of push-pull and swing hinges; space-saving with high sealing | the sash completes the last part of its travel and presses sideways onto the gasket, not merely arrives at the end of the track |
| Four-sided continuous sealing strip with upper rail frame sealant | the corners are joined rather than butted, and the sealant bead is applied under controlled conditions and survives the first years |
| Opens without taking up indoor space; large opening, smooth operation | you do not then add an inward-opening screen, which takes the indoor space straight back |
| Side pressure rubber strip seal, casement-level sealing performance | the handle is turned and the locking points actually compress the gasket; and you know which test the comparison refers to |
| German ROTO hardware for side-pressure windows and doors | the purchase order names the hardware by component and part number, not by country |
| 200 kg load-bearing pulleys | you read it as a per-sash roller rating measured on a specific glass build, not as a maximum sash size |
| Eight-point locking system | all eight points are engaged and adjusted, which is a commissioning step and not a factory fact |
| Extended functions: inward-opening sash mesh, integrated glass railing, anti-theft grille, inward/outward opening mesh | you have decided them before the profile is cut, because three of them change the opening and one changes which code applies |
Before any of the eight features mean anything, one piece of physics has to be understood, because everything on the list is a response to it.
A sash that slides has to be loose. For a heavy glazed panel to roll along a track, there must be a deliberate clearance between the moving sash and the fixed frame. A European aluminium fabricator puts it plainly in a technical article on sliding airtightness: the panel needs a small constructional gap so that the rollers can roll freely, and air, dust, noise and rainwater all find their way in through exactly that gap.
The industry’s traditional answer is pile weatherstrip, also called brush seal. It is the right answer for a sliding surface, and it is a compromise. The bristles touch; they do not compress. Under sustained wind pressure air passes through them. The same European source describes the bristles losing volume and flattening within roughly three to five years of normal operation, and notes that brushes collect dirt, which accelerates the decline. An Australian fabricator’s gasket guide makes the same point from the other direction: sliding windows use pile and fin seals precisely because they must accommodate lateral motion without creating friction.
Now try to upgrade that. Put a proper compression gasket on a plain slider and the window stops working. The Australian guide warns that retrofitting a casement-style compression gasket onto a sliding rail produces drag, stutter or binding. A seal specialist says it more bluntly: a compression seal on a sliding surface will either tear off or make the sash stiff to move.
So the choice is stark. Either you accept a wiping seal, or you add a mechanism that takes the sash out of its sliding plane before it seals. That is the entire reason the side press window exists, and it is the reason the sealing feature and the locking feature are not two separate bullet points.
There are two families of mechanism that solve the gap problem. The first is lift-and-slide: the sash is raised onto its seal, or lowered onto it, so that the slide happens with the gasket clear of the track and the seal happens with the gasket crushed by the sash weight. The European fabricator quoted above describes this sequence explicitly, and notes that this is why perimeter EPDM gaskets are paired with advanced mechanisms rather than fitted to simple sliders.
The second family presses sideways instead of vertically. The sash travels along its track in the usual way, then in the last part of its travel the hardware converts the rotation of the handle into a lateral movement that pushes the sash off the slide plane and onto a continuous rubber seal around all four edges. A Chinese hardware-system reference describes the working part as a wedge-form locking block: as the sash closes, the locking point meets the frame first, and continued pressure produces a small elastic deformation of the gasket, which is what makes the seal. The published figure in that reference is in the range of three to five millimetres of compression.
Two consequences follow, and they are the most useful things in this article.
First: the seal does not exist until the handle is turned. A side press sash that has been pushed shut but not locked is not a sealed window. It is a sliding window with an expensive gasket sitting a few millimetres away from where it would need to be. The feature is a state, not a property.
Second: the eight-point lock is not the security feature. It is the sealing actuator. Reading “side pressure rubber strip seal” as item four and “eight-point locking” as item seven splits one mechanism into two marketing lines. Remove the lock and the seal is a strip of rubber near a gap. The lock is what generates the compression, the same way a vice generates clamping force.
This also tells you where the operating force goes. The handle has to compress a gasket whose length grows with the sash perimeter. A larger sash means more gasket to squeeze through the same number of locking points, which is why the maximum sash size and the feel of the handle are tied together on a side press unit in a way they are not on a plain slider. It is a real coupling, and it is worth asking about rather than discovering.
This is the honest reading of that phrase, and it matters because it is the line most often quoted back at a supplier in an argument.
“Casement-level” is a comparison against a sliding window’s pile seal, not a claim to be a casement window. A casement sash closes onto a continuous compression gasket around the full perimeter with the frame contact distributed along whole edges. A side press sash arrives at the same kind of compression, but through a finite number of discrete locking points spaced along the perimeter. The seal quality between the points depends on the sash’s own stiffness and on the compression being even. That is a genuine improvement on a brush seal and it is not the same thing as a casement.
So the useful question is not “is it casement-level”. It is: what air permeability class and watertightness class was it tested to, under which standard, and was the test specimen the side press configuration or the fixed light? Those are three separate questions and suppliers frequently answer only the first.
For the TS130 we do not publish a thermal transmittance value or a tested permeability class. That is not a weakness in the product, it is a gap you should fill with a document rather than an adjective. In our range the published thermal values are system values for the casement and tilt-and-turn series, not whole-window values and not certification under a national rating scheme; the sliding series has no published value. If your submission needs a number, ask for a calculated whole-window value for your exact size and glass build, on the same basis as the rest of your schedule.
Eight locking points are not eight engaged locking points until someone adjusts them. This is the single most under-specified commissioning step in the whole unit, and it is easy to understand why once you know what the parts do.
On a ROTO-type system the moving parts on the sash are mushroom or roller cams, and the receiving parts on the frame are called keeps. A hardware distributor’s description of ROTO keeps lists several types, including mushroom, roller, hook and shoot-bolt, and notes that many keeps are made with elongated screw holes or an eccentric so that an installer can fine-tune how hard the sash is pulled onto the gasket. A European window fabricator’s adjustment guide describes the same adjustable cams on the sash: they are eccentric, they are usually turned with a four millimetre hex key, and the position is read from a mark on the cam rather than from a direction of rotation. Mark pointing toward the gasket is maximum pressure; mark pointing away is minimum; the factory position is in the middle.
The same guide recommends the paper test: close the window on a sheet of paper, pull it, and if it slides out easily the sash is not clamping in that spot. It also warns that adjustment has a limit. Too loose and air comes in. Too tight and you strain the gasket and the hardware and the handle becomes hard to turn. And it states the case where adjustment will not help at all: cracked or hardened gaskets, or a perimeter that is not airtight because of the installation into the wall rather than the window.
Put that together and the picture is clear.
Ask for two things on the order: a lock point layout drawing with the spacing dimensioned, and a written statement of who performs the first adjustment and when. A hardware set with no commissioning step in the contract is a hardware set that will be commissioned by whoever is holding the hex key on handover day.
The number is real and it is generous. It is also routinely read as something it is not.
It is per sash, not per window. In a middle-fixed unit with two movable sashes, each sash has its own carriage and its own rating. The rating does not add up across the unit and it does not tell you anything about the fixed light above or beside it.
It is a roller rating, not a maximum sash size. A manufacturer publishes a largest sash against an assumed glass build. Change the glass and the size that the same hardware can carry changes with it, which is why “what is the maximum size” is the wrong question and “what is the maximum size with this glass build” is the right one.
You can do the arithmetic yourself with the figure the industry commonly uses for glass mass, roughly two and a half kilograms per square metre for every millimetre of glass thickness. A standard insulating unit with two six millimetre panes is twelve millimetres of glass, so around thirty kilograms per square metre of glass alone. Take a modest opening such as a 24x36 sliding window, which is about 610 by 914 millimetres, or a little over half a square metre: the glass is roughly seventeen kilograms before you add a single gramme of aluminium. Against a two hundred kilogram carriage that is a very large margin.
That margin is the point. On a small or mid-size sash the rating is not the constraint at all. The constraint is the largest panel you can actually get into the room, the glass build you want, and the operating force at the handle. Save your questions for those.
The side press adds a load a plain slider’s rollers never see. A conventional sliding sash puts a vertical load on its rollers and a varying wind load on its guides. A side press sash also has to resist the lateral force generated when the handle drives it sideways onto the seal, and then hold that position. The rollers and the upper guide are doing two jobs rather than one, and the second job is applied every time the window is locked rather than once a season.
So the questions worth asking are the boring ones: what is the vertical adjustment range on the roller, and can it be reached without taking the sash out of the frame? Roller adjustment is how you compensate for the sash settling over the years, and if it cannot be done in place it becomes a two-person job in a room with furniture in it. Ask for the roller part number as well. It is the one item on this window that you will eventually buy again.
This feature is the reason most people look at a side press window instead of a casement. It is also the feature most easily given straight back.
The sash itself slides within the plane of the window and presses outward to seal. Nothing swings into the room. That is genuinely different from a casement, where the sash sweeps an arc you have to keep clear of curtains, blinds, a kitchen tap, a bed headboard or a basin.
Now look at the last line of the feature list. The extended functions include an inward-opening sash mesh. An inward-opening screen is a hinged leaf that swings into the room. It takes back the exact clearance the side press mechanism saved you, and it has to be opened before the window can be operated, which means the screen accumulates more operating cycles than the window does.
This is not an argument against the screen. It is an argument for deciding the screen before you decide anything else, because the screen direction is fixed by what is in the room and the window type is fixed by the screen. If your reason for choosing side press was a blind, a tap or a bed, an outward-opening or rolling screen keeps the benefit and an inward-opening one cancels it. There is also a second thing a sliding sash does take: when it is open it occupies the other half of the opening, and in a middle-fixed unit with two movable sashes it occupies two zones of glass rather than one.
A related note for anyone specifying a slide swing door alongside the windows: the same trade-off applies at door height, where a screen leaf is bigger, heavier and swings further.
Two different claims sit in this one line and they should be separated, because they fail in different ways.
“Continuous” is a claim about corners. A gasket running down four edges is only continuous if the four corners are made continuous. That is done either with a moulded or vulcanised corner or by cutting and joining on the bench, and the two are not equivalent over a long service life. Ask which one you are getting. The corner is where a perimeter seal normally stops being a perimeter.
The upper rail sealant is not an extrusion. Every other item on the feature list is a piece of aluminium, a piece of rubber or a piece of hardware. This one is a material applied by a person. It depends on surface preparation, ambient conditions and bead size, it is the shortest-lived element in the assembly, and it is the one most likely to be done on site rather than in the factory.
None of that makes it a bad detail. A properly applied bead between the top track and the frame is a sound way to close the path that wind-driven rain takes over the head of a sliding unit. It does mean the question is not “does it have sealant” but who applies it, to what written procedure, and what happens to it in year six. We have written separately about track and perimeter sealing; the short version is that a sealant bead is a maintenance item with a documented method, and it should be named in the handover documents rather than assumed.
Roto Frank makes a very large number of hardware systems, and the keeps and cams are engineered to suit specific profile systems rather than being universal. The distributor description quoted earlier makes this explicit: ROTO supplies hardware to many profile houses, and the keeps are matched to each system’s espagnolette bars and multi-point locks. Mushroom cams and roller cams need different keeps. So “ROTO hardware” without a series, a finish and a component list is a marketing token, not a specification.
There is a second reason to ask for the list by component. A window unit is not assembled from one supplier. On this and on every other unit in the range, the transmission box, the locking points and the rollers can come from different makers, and that is normal and not a defect. What you want is the bill of materials:
One clarification on cycle testing, because it is quoted loosely across the industry and we would rather be precise. Where a cycle figure is published for a hardware set in our range, it is a bench test result for that configuration. It is not a service life, and it does not transfer to another series or to a loaded sash being opened and closed in a building. Treat it as a comparative datum between two hardware options, not as a promise about years.
These are listed at the bottom of the feature page as options. They are not options in the sense that a colour is an option. Three of them change the physical opening, and one of them changes which set of rules the assembly is judged against.
| Extended function | What it changes physically | What it changes contractually |
|---|---|---|
| Inward-opening sash mesh | A hinged leaf swings into the room; needs clear indoor space and adds an operating cycle every time the window is used | Cancels the space-saving benefit if that was why you chose the product; must be decided before the frame is made |
| Integrated glass railing | The frame stops being a window frame and becomes a barrier post carrying a horizontal line load at its top edge | Moves the assembly into barrier rules with their own load cases, glass type rules and height rules, and a separate responsible engineer |
| Anti-theft grille | Adds a visible element across the opening that has to be cleaned and that may sit in front of the sash travel | Can conflict with escape-route requirements and with the barrier gap rules if it is also acting as guarding |
| Inward or outward opening mesh | Sets which side of the opening needs clearance and which side is reachable for cleaning | Outward-opening screens on upper floors become a cleaning and access question for the building, not for the window |
A window is designed against wind pressure, which is a load spread over an area. A barrier is designed against something else entirely: a horizontal line load applied at the top edge, plus a uniformly distributed load across the infill, plus a concentrated point load. Published guidance for the UK system, referencing BS 6180 and the Eurocode, gives line loads by occupancy that run from 0.36 kN/m for a single dwelling up through 0.74 kN/m for residential balconies, 1.5 kN/m for retail and 3.0 kN/m for assembly areas. The Australian framework uses AS/NZS 1170.1, where a residential barrier is commonly designed for a 0.5 kN/m line load or a 0.5 kN concentrated load, alongside glass selection to AS 1288. The exact numbers are not the point and will be set by your own code; the shape of the load is the point.
That load has to go somewhere. In a window-integrated railing it goes into the window frame and through it into the building. A frame that was sized as a window frame has not been checked as a barrier post, and no wind-load test result on a window tells you whether it can be one. That is a separate structural check, and it is normally the responsibility of a named engineer on the project rather than the window supplier.
Three more rules arrive with the barrier, and they are easy to miss because none of them are window rules. The 100 mm sphere rule: no opening in the barrier should pass a 100 mm sphere, which governs gaps between panels and between a panel and a post or wall. The glass type rule: where glass is the sole barrier, or where the ｄｒｏｐ is significant, laminated glass is generally required rather than toughened-only, with a continuous handrail as the alternative in some regimes. And the height rule: minimum heights are set by location and use, and the figure in front of a window opening is typically lower than the figure for a balcony edge or a stair.
The practical advice is simple. If your project needs a barrier in front of a window, decide it at the same time as the window, and say so in the first email. A railing that is added as an accessory after the profiles are cut is a railing that has to be engineered around an existing extrusion.
The published specification for the TS130 is short: 1.8 to 2.0 millimetre wall thickness, 6060-T66 alloy, PA66GF25 thermal break, 130 millimetre frame depth, 55 millimetre glass sash thickness, 75 millimetre sash width, 26 millimetre frame width, and a track height given as 53/31 millimetres. Three of those numbers are regularly misread.
One more honest note about the alloy and temper. 6060-T66 with a PA66GF25 thermal break appears across our range, not only here. That means the alloy is not what distinguishes this window from the others, and a supplier who answers a performance question by naming the alloy is not answering the question. What varies between series is the wall thickness, the section geometry, the thermal break width, the corner construction and the glass package.
This table is the one to attach to a purchase order. The right-hand column is not a list of weaknesses; it is a list of questions that have not been asked yet.
| Published | You still need to ask for | Why the gap exists |
|---|---|---|
| Side pressure rubber strip seal | Air permeability, watertightness and wind resistance class, with the standard named and the tested configuration identified | A seal is a state produced by the hardware, so it has to be tested in the locked side press condition, not as a fixed light |
| 6060-T66, PA66GF25, 1.8 to 2.0 mm | Whole-window thermal transmittance and solar heat gain coefficient for your size and glass build | The published thermal values in our range are system values for other series; the sliding series has none published |
| 200 kg pulleys | Maximum sash width and height at your specified glass build, plus roller adjustment range and replacement method | Glass mass dominates the load, so the size limit moves with the glass you choose |
| Eight-point locking | Dimensioned lock point layout, plus who performs and records the first adjustment | Points are only engaged if the keeps are set; engagement is a commissioning outcome |
| German ROTO hardware | Component-level bill of materials with part numbers, finish and corrosion class | A brand name is not a part number and does not tell you what you will reorder in ten years |
| Four-sided continuous seal, upper rail sealant | Corner construction of the gasket, and the written sealant procedure with who applies it | Continuity is a corner detail, and a bead is an applied material rather than an extruded one |
| Integrated glass railing option | Barrier load category by occupancy, glass type, height and gap compliance, and the name of the engineer signing it | Barrier rules are a different regime from window rules and they are set locally |
| 130 mm frame depth | Confirmation that your wall build-up can take the depth, checked before the opening is formed | Frame depth is a property of the series and it is not negotiable on site |
It is a good window for a specific set of problems and a poor one for others. Here is where we would talk you out of it.
The last column is the useful one. It is what a real answer sounds like when it contains no information.
| Ask | A useful answer | An answer with nothing in it |
|---|---|---|
| Which standard and class was the side press configuration tested to? | A named standard, a class, and confirmation the specimen was the sliding sash in the locked condition | “It meets European standards” |
| Maximum sash size at my glass build | Two numbers for the specific insulating unit you name, with the build stated on the drawing | “Up to 200 kg” |
| Lock point layout | A dimensioned drawing showing where all eight sit on your sash height | “Eight-point as standard” |
| Who commissions the locking points | A named party, a stage in the programme, and a signed record | “It is adjustable” |
| Roller adjustment and replacement | The range in millimetres, and whether it can be done with the sash in place | “Heavy duty rollers” |
| Gasket corner construction | Moulded or vulcanised corner, or cut and joined, stated plainly | “Continuous sealing” |
| Upper rail sealant | Factory or site, the product, the surface preparation, and the inspection step | “Sealed with sealant” |
| Hardware bill of materials | Line by line with part numbers and finish | “German hardware” |
| Glass railing, if selected | Occupancy load category, glass type, height, gap check, and the signing engineer | “Optional railing available” |
| Screen direction | A choice made against a drawing of the room, with the obstruction marked | “Screen optional” |
No. Both exist for the same reason: a sliding sash needs clearance, and a compression gasket cannot work across that clearance. Lift-and-slide raises or lowers the sash onto the seal and uses the sash weight to compress it. Side press moves the sash laterally onto the seal and uses the locking hardware to compress it. The difference matters to you because the operating force, the hardware set and the commissioning steps are different.
Because shut is not the same as locked. Until the handle is turned and the locking points drive the sash sideways, the gasket is sitting near the frame rather than against it. If it still leaks when locked, the next thing to check is whether all the locking points are engaged, which is an adjustment, and after that the corner condition of the gasket. The paper test takes a minute and tells you where.
The hardware is designed to be adjusted, and the reason it is designed that way is that gaskets relax. A fabricator’s published adjustment guide for ROTO-type hardware describes a firmer setting for cold weather and a lighter one for warm, read from the mark on the cam rather than from a direction of rotation, usually with a four millimetre hex key. That is maintenance, not a defect. The mistake to avoid is tightening one cam much more than the others, which makes the sash press crookedly.
Treat that as a structural question, not a product option. A barrier is designed against a horizontal line load at its top edge and a point load, by occupancy category, and it has its own rules on height, gaps and glass type. Those are set by your local code and signed by the project engineer. We can supply the profiles, the test evidence and the drawings; we cannot be the party who decides your barrier load category.
No. It is a per-sash roller rating, and the mass it has to carry is dominated by the glass, at roughly two and a half kilograms per square metre per millimetre of thickness. A thicker insulating unit reduces the sash size the same hardware can carry. Always ask for the maximum size against your specific glass build rather than against the rating.
No, and this is worth being precise about. The published 26 millimetres is the frame width. The published 75 millimetres is the sash width, which is the aluminium band around the glass. When you compare sightlines between products, ask which quantity is being quoted and ask for it marked on a section. A number without a dimensioned drawing is not a comparison.
A feature list is a good way to find out what a product is trying to do. It is not a specification. The specification is the drawing with your dimensions on it, the standard with your class in it, and the purchase order with the part numbers in it. Send us those three and we will tell you what the window can do.
