We have written elsewhere about how to measure and frame a rough opening for a casement window. This piece starts where that one ends, and it starts with an awkward fact: the hole that suits a 72 x 60 casement is not automatically the hole that suits a 72 x 60 slider. Same nominal size, same wall, and three requirements the casement never had to meet.
Ask three suppliers for the rough opening of a 72 x 60 sliding window and you can easily get three answers spread across about 38 mm, and one of them is smaller than the number in the name. That spread is larger than the entire clearance you are supposed to leave around the frame. Which is another way of saying: if you frame to the wrong convention, you do not shim your way out of it. You rebuild the opening, or you order a different window.
72 x 60 is a nominal call-out. Converted, it is 1829 x 1524 mm, and it describes an opening roughly 1.83 m wide and 1.52 m tall. That is a wide, horizontal shape, which is exactly why sliders dominate this size band and casements do not: a casement at 1829 mm would need two sashes meeting at a mullion, while a slider does it with two sashes that simply pass each other.
But nominal is not the frame, and the frame is not the hole. Here are three conventions that are all in circulation for windows called 72 x 60:
| Convention | Rough opening (inches) | Rough opening (mm) | What it assumes |
|---|---|---|---|
| Unit is made 1/2 in under the nominal call-out, so the hole lands on a clean figure | 71.5 x 59.5 | 1816 x 1511 | Found in a published product listing for a 72x60 unit, where the rough opening is given as half an inch less than the name in both directions |
| Hole equals actual frame plus 1/2 in, which is 1/4 in per side | 72.5 x 60.5 | 1842 x 1537 | The familiar framing rule. Note that installation guides which say "leave a 1/4 in gap" are describing a per-side clearance, so they land on this same row |
| Hole equals actual frame plus 3/4 in to 1 in | 72.75 to 73 x 60.75 to 61 | 1848 to 1854 x 1543 to 1549 | Given as an aluminium window supplier's own published recommendation for its 72 x 60 units |
Low answer to high answer is 71.5 to 73 in, or about 38 mm. There is no shim pack that covers 38 mm.
It is worth being clear about why a gap exists at all, because it changes how you read the table. Aluminium expands roughly twice as much as steel for the same temperature change. Take the coefficient as about 23 micrometres per metre per degree Celsius, and a 1829 mm frame seeing a 40 degree swing changes length by roughly 1.7 mm. A 914 mm frame sees half that.
So the perimeter gap scales with the width of the unit. It is not slack left for imprecise framing, and it is not something you can borrow from. A six-foot window genuinely needs more room around it than a three-foot one.
At 1829 x 1524 mm you have about 2.79 square metres of opening. Split two ways, each sash is roughly 890 mm across, and once you subtract the stiles the glass in each sash is around 1.0 square metre.
Now weigh it. Glass runs about 2.5 kg per square metre for every millimetre of glass thickness, so a 6+12A+6 build-up carries roughly 30 kg of glass per square metre. One sash therefore holds about 30 kg of glass plus the aluminium around it: call it 35 to 45 kg depending on the glass you specify.
The TS130 side press window carries 200 kg load-bearing pulleys. At this size, then, the sash is using a fraction of what the hardware can carry, and the margin is wide.
Two more things fall out of the numbers. At 1524 mm tall you are just past the 1500 mm mark that at least one widely used aluminium installation guide treats as the threshold for adding mid-height fixings on each jamb, so a 72 x 60 sits in a slightly different fixing regime than a 60 x 48 does. And if you were considering three panels at this width, each sash lands near 600 mm overall, with the visible glass in each appreciably narrower than that. We have argued before that around 600 mm is roughly the practical floor for a three-panel slider; at 1829 mm, two panels is usually the better call.
A casement distributes its problems. The sash hangs off hinges, the load goes into the jambs, and when something is a few millimetres out you adjust the hinges and move on. A slider has none of that latitude. These are the three places where it shows.
A window fitters' guide used across the replacement industry puts it flatly: the most important aspect of installing a sliding window is having a level sill. If that sill is crowned or concave, the track the sash rolls on will not let the sash close properly, and the interlock between the sashes will not engage, which then presents as air leakage and, sooner or later, water.
Three details in that guidance matter more than the headline:
The same guide gives the reason, and it is the best sentence anyone has written on this subject: because there is no gravity to help the sash operate smoothly, the squareness of the opening matters more for a slider, so that the operating sashes do not bind up. On a double-hung, gravity assists. On a slider, nothing assists. The sash is a rigid rectangle riding in a rigid channel, and if the opening is racked the sash is being asked to be a parallelogram.
Roller adjustment exists, but it is measured in a few millimetres and it usually means taking the sash out of the frame to get at it. It is not a substitute for a square hole.
Two related habits separate a slider that works from one that binds. Install it relaxed: do not push the frame hard against a stop, and do not anchor it in a way that twists it. And put a packer behind every fixing point, because a screw driven through unsupported aluminium pulls the profile inward and creates a pinch point. One published aluminium installer tolerance calls for diagonals to match within 2 mm. Treat that as that installer's number rather than a universal rule, and check sash operation before you drive the last fixings home rather than after.
Sliding sashes are generally held in by gravity and the upper channel, not by clips. Published guidance puts the clearance most frames leave above the sash at 10 to 15 mm, and it is there for one reason: to lift the sash up into the head pocket, swing the bottom inwards past the sill track, and take the panel out. Anti-lift blocks in the head track, where fitted, have to come out first.
That clearance belongs to the window, but a rough opening can destroy it. If a header bears down on the frame head, or the frame gets jacked or twisted while it is being fixed, the pocket closes. At that point the rollers cannot be serviced and the glass cannot be replaced without dismantling the frame. The same clearance is precisely why anti-lift blocks exist, so it is a servicing feature and a security exposure at the same time, and it is worth asking the factory for it in millimetres.
And one more constraint, from the same fitters' guidance: no anchor screws should pass through the sill or track of a slider. A screw through the bottom track is a water path into the opening. Which means the head and jambs carry all the anchoring, and the flatness of the sill has to come from the opening itself rather than from fasteners pulling it into shape.
| Dimension | What it governs | How it fails | At 72 x 60 |
|---|---|---|---|
| Width | Sill flatness, expansion allowance, number of panels | A crown in the middle of the sill is invisible to the eye and fatal to the interlock | 1829 mm is long enough that corner-only shimming will not hold the track flat |
| Height | Fixing schedule, lift-in geometry, sash weight | Too few jamb fixings lets the frame flex under wind load and distort the seal contact | 1524 mm is past the 1500 mm threshold used by at least one installation guide for extra mid-height fixings |
| Depth | Whether the frame fits the wall at all | A frame deeper than the cavity has to project into the room, and nobody planned the reveal | A 130 mm frame does not disappear into an 89 mm stud cavity |
None of this scales down the way people assume. A 48 x 24 sliding window is a third of the height but still around 1.2 m wide, so sill flatness still governs and the lift-in clearance above the sash is unchanged. A 36 x 24 sliding window is short enough that the jamb fixing schedule stays simple and the sash is light enough for one person to lift out single-handed, but the sill still has to be flat, because there is still no gravity helping the sash along. And a 12 x 24 sliding window is the size where everybody stops bothering: almost no expansion to absorb, a sill you can true up with packers alone, and no visible consequence from getting the head pocket slightly wrong, right up to the day a roller seizes and you find the sash cannot come out.
One manufacturer's own care guide says it in capitals: if you see water in the bottom track or sill area of your windows, there is no cause for alarm. The outer track of a slider is designed to collect water and pass it out through weep slots. It only becomes a leak when water crosses the inner rail.
An out-of-level rough opening breaks that arrangement in a specific way. Water runs to the low end, the weeps at the high end stop doing anything, and the low end is suddenly handling more than it was proportioned for. Add a sill that slopes inward rather than outward and you have turned a designed puddle into an overflow. It is the same advice from two directions: check the sill with a level across the full width, and make sure nothing in the exterior finish covers or obstructs the weep path.
| Series | Frame depth | Published track and drainage detail | What it means for the sill |
|---|---|---|---|
| TS130 side press window | 130 mm | Track height 53/31 mm; four-sided continuous sealing strip with sealant between the upper rail and the frame | The seal is continuous, so it only compresses evenly if the frame is square and the track is flat. Confirm which of the two track heights is outer and which is inner before you set the sill board |
| SL112/167 | 112 mm (single/two track), 167 mm (three track) | 45 mm high-ｄｒｏｐ bottom track; optional 85 mm water barrier | A tall ｄｒｏｐ gives you more tolerance for a sill that is not perfect, at the cost of a bigger step at the threshold |
| SL126/182 | 126 mm (two track), 182 mm (three track) | High track 43 mm, low track 8 mm; eave-style waterproof design; bottom track water-blocking edge | Low track at 8 mm is the accessible option, but it has very little height to hold water, so sill level matters more, not less |
| SL155 | 155 mm (four track) | Passive check valve drainage, to speed up removal and prevent backflow | A one-way valve only works if the track is level enough for water to reach it. It is not a cure for a sloped opening |
| C116 (casement, for contrast) | 116 mm | Flat-channel, obstacle-free easy drainage | A casement sheds water at the sill face and the frame stays put. This is the difference the whole article is about |
Rough opening charts give you two numbers. The wall gives you a third, and it is the one that most often decides which series you can actually use.
A 2x4 stud wall leaves a cavity of about 89 mm. A 2x6 leaves about 140 mm. The TS130 frame is 130 mm deep, which fits the second and not the first. If your wall is the first, you need a deeper wall, a buck or jamb extension, or you accept the frame projecting into the room and plan the reveal around it. All three are decisions made before the opening is built.
For reference, the published frame depths across the range are: TS130 at 130 mm, SL112/167 at 112 mm or 167 mm depending on track count, SL126/182 at 126 mm or 182 mm, SL155 at 155 mm, AW90 at 90 mm, C120 at 119 mm, C116 at 116 mm and C113 at 113 mm.
| Item | What ALPES publishes | What you still need in writing |
|---|---|---|
| Profiles | 6060-T66, 1.8 to 2.0 mm for TS130 | Wall thickness at the specific sections that carry sash load, if your engineer wants it named |
| Thermal break | PA66GF25 multi-chamber | The strip width in millimetres for this series, and a whole-window U-value calculated to the standard your project files under |
| Thermal performance | K = 1.3 (AW90), 1.6 (C120), 1.7 (C116) | Those are system values, not whole-window values and not NFRC figures. TS130 has no published K value. SHGC is not published for any series. Ask for both |
| Sliding hardware | 200 kg load-bearing pulleys, eight-point locking, ROTO side-pressure hardware | Confirmation that 200 kg is per sash, and the glass weight the maximum sash size was calculated against |
| Sealing | Four-sided continuous sealing strip with sealant between upper rail and frame | The head pocket clearance in millimetres, and whether the sash can be removed with the frame installed |
| Dimensions | Frame 130 mm, glass sash 55 mm, sash 75 mm, frame 26 mm, track height 53/31 mm | Maximum sash width and height for TS130 at your glass specification. Not published, and not something to assume from the pulley rating |
| Corrosion and strength | 240-hour salt spray test, 5,000 N shear resistance | Both figures belong to AW90 and do not transfer to the sliding series. If your site is coastal, say so up front and ask what coating and hardware grade can be supplied |
| Cycle testing | CMECH hardware, 30,000 cycles (C113) | That is a hardware bench cycle count, not the service life of a sliding sash and not a TS130 roller figure |
| Capacity | 100,000 square metres across Foshan and Zhaoqing | Which line your order runs on, and to see it |
| Scope | We design, manufacture and supply the window, and issue shop drawings | We do not measure, do not frame, do not size your header and do not install. The rough opening, the header and the flashing are your builder's and your engineer's scope |
| Item | What to write down | What it decides |
|---|---|---|
| Actual frame size | Width and height in mm, from the shop drawing | 72 x 60 is a name, not an orderable dimension |
| Rough opening | Width and height in mm, plus which convention produced them | The published conventions differ by about 38 mm |
| Sill condition | Crowned, concave or sloped, and the thickness of the levelling board | The board consumes vertical rough opening, so decide it before you order |
| Support under the sill | Flat, continuous, and wider than the tracks | Shims alone let the track deform under sash load |
| Wall depth | mm from inside face to outside face | Which series fits, and whether you need a buck or an extension |
| Header | Confirmed by your engineer or local authority, in writing | Six feet of removed stud is a structural question. A window supplier cannot answer it |
| Anchoring | Jamb and head locations only. Nothing through the sill | A screw through the bottom track is a water path into the opening |
| Weep access | Confirmation that no exterior finish covers the drainage path | A blocked weep turns a designed puddle into an overflow at the inner rail |
| Glass build-up | The exact configuration, for example 6+12A+6 | Sash weight, maximum sash size and roller loading are all set against it |
| Sash removal | Head pocket clearance in mm, anti-lift block type, removable with frame installed | Otherwise the first roller replacement becomes a frame replacement |
| Who owns the tolerance | A named person who signs off the opening before the window ships | Most disputes at this size are about who measured, not about what was measured |
It depends whose convention you are using. A published product listing for a 72x60 unit gives 71.5 x 59.5 in, or 1816 x 1511 mm. The common rule of frame plus 1/2 in gives 72.5 x 60.5 in, or 1842 x 1537 mm. A published aluminium supplier recommendation of frame plus 3/4 to 1 in gives 72.75 to 73 x 60.75 to 61 in, or 1848 to 1854 x 1543 to 1549 mm. Ask the factory for the actual outside frame dimension in millimetres and work from that.
It is a large opening, about 2.79 square metres, but the load per sash is modest. Roughly 35 to 45 kg per sash against a 200 kg rated pulley leaves a wide margin. The constraint at this size is the flatness of the sill and the depth of the wall, not the hardware.
No. Published installation guidance for sliders is explicit that no anchor screws should pass through the sill or the track. It creates a path for water to get under the window and into the opening. Anchor through the jambs and head, and make the sill flat instead.
Almost always an unlevel bottom track. A slider has no gravity assist holding the sash where you left it, so a track with any slope to it will let the sash run downhill. Check the sill with a level across the full width, not just at the two ends, and remember that a crown in the middle will not show up on a level placed at the corners.
Two candidates. Either anti-lift blocks are still sitting in the head track, which have to be cleared first, or the head pocket clearance has been lost. Most frames leave somewhere around 10 to 15 mm above the sash for exactly this, and a header bearing on the frame head or a frame that was racked during fixing can close it. If it is the second, treat it as a rough opening and framing defect, not a hardware fault.
No. We manufacture, publish the series data and issue shop drawings for what you order. Measuring the opening, sizing the header, flashing and installing are your builder's and your engineer's responsibilities, and we would rather say that plainly now than argue about it after delivery.
