Double glazed sliding windows are windows with two panes of glass in a sealed unit, set in sashes that glide sideways along a track. They suit tight spots because nothing swings out, and a standard two-panel slider opens across about half its width for airflow. In a uPVC frame they cut heat transfer and outside noise compared with the single glazed aluminium sliders found in many older Perth homes.
This guide explains how a double glazed slider is built and how much air it really lets in. It covers ways to get more ventilation from one, the comfort and noise gains, and the glass, lock and screen options. It also sets out what sliders cost in Perth and which rooms they suit best.
How Double Glazed Sliding Windows Work
A double glazed sliding window combines three parts, which are a sliding sash, a sealed double glazed unit and an insulated frame. Each part does a different job, and together they decide how the window feels to use and how well it performs. These are the three parts that make up a double glazed slider.
The Sliding Sash and Track
A sash is the framed panel of glass that moves. In a standard two-panel slider, one sash is fixed and the other runs on rollers along a track at the sill, passing behind the fixed panel when it opens. Because the sash moves sideways instead of swinging, the window needs no clearance inside or outside the opening. That makes sliders practical above kitchen benches, beside paths and in narrow side returns. Larger openings can use three or four panels, with two sashes sliding towards each other from the ends.
The Sealed Double Glazed Unit
The glass in each sash is a sealed double glazed unit, also called an insulated glass unit (IGU). An IGU is two panes of glass held apart by a spacer around a sealed, gas-filled gap. Canon Double Glazing’s sliders use an 18 mm unit, made from two 4 mm panes around a 10 mm cavity. That cavity is the part that slows heat moving through the glass, because still gas conducts heat far less readily than glass does.
The uPVC Frame and Seals
The frame holds the sashes and carries the seals that keep air and water out. Canon Double Glazing’s sliding series uses an 80 mm uPVC profile with three internal chambers, reinforced with steel for strength. uPVC (unplasticised polyvinyl chloride) is a rigid plastic that insulates far better than aluminium. Double-sided EPDM gaskets, which are flexible synthetic rubber seals, close the gaps where the sashes meet the frame.
A slider built this way is easy to live with and efficient at keeping heat out. The trade-off sits in how the sash opens, which limits how much fresh air can pass through at any one time.
How Much Airflow Does a Sliding Window Give?
A standard two-panel sliding window opens across about half its width, because the moving sash has to park behind the fixed one. That is enough airflow for most bedrooms and living areas in a Perth home. The National Construction Code requires habitable rooms to have openings of at least 5% of the floor area, and a well-sized slider meets that easily. The table below compares sliders with other common window styles.
| Window style | Share of window that opens | How it opens | Airflow strength |
|---|---|---|---|
| Sliding | About 50% | Sash slides behind the fixed panel | Steady airflow with no swing space needed |
| Double hung | About 50% | Sashes slide up and down | Opening top and bottom lets warm air escape |
| Casement | Most of the opening | Sash swings out on side hinges | Catches and deflects breezes from changing angles |
| Awning | Limited by how far the sash projects | Sash pushes out from a top hinge | Can stay open in light rain |
| Louvre | Up to 95% | Glass blades tilt open | Largest open area of any style |
The Australian Government’s YourHome passive cooling guide states that a sliding window lets about 50% of the window space open to the breeze, while louvre windows can open up to 95%. YourHome also recommends casement windows for catching and deflecting breezes that arrive from changing angles. For most rooms, half the window is plenty. The National Construction Code measures a room’s ventilation by the size of the openable sash, and sets the minimum at only 5% of the floor area. The real limit of a slider is that it cannot scoop a breeze running along the wall the way an open casement sash can.
A slider’s open area is fixed by its design. How much of that open area actually turns into a cooling breeze depends on where the window sits and how it works with the rest of the house.
How to Get More Ventilation From Sliding Windows
You get more airflow from sliding windows by placing them to catch the breeze and giving that breeze somewhere to leave. Air only moves through a room when it has both an inlet and an outlet. These steps help a slider move as much air as possible.
- Create cross-ventilation. Put openings on opposite or adjacent walls so air can flow straight through the room.
- Face the breeze. Place sliders on the south-west side where possible to catch Perth’s afternoon sea breeze.
- Choose the sliding side. Specify which sash opens so the open half sits on the side the breeze comes from.
- Pair with a higher opening. A high awning or louvre window lets warm air escape near the ceiling while cooler air enters lower down.
- Open up at dusk. On hot days, keep windows shut and blinds drawn until the outside air is cooler than the inside air.
Perth has a natural ally for this approach. The Bureau of Meteorology describes the Fremantle Doctor as the afternoon sea breeze that usually arrives late in the day, almost always from the south-west, bringing much cooler air after hot easterly days in summer and early autumn. Sliders opened on that side of the house can start clearing built-up heat as soon as the change arrives. Rooms that need even more air, such as a hot west-facing kitchen, may suit double glazed casement windows on the breeze side. Once the cool change has passed and the windows are shut again, the glass takes over the job of holding the room at a comfortable temperature.
Why Double Glaze a Sliding Window?
Double glazing a sliding window keeps a room cooler in summer and warmer in winter by slowing the heat that passes through the glass and frame. A single pane of glass lets heat flow almost freely, and an aluminium frame adds a second path because metal conducts heat so well. Swapping both for a sealed unit in an insulated frame tackles the two weak points together. The result is a window that stays closer to room temperature on the inside face, so the area beside it no longer feels hot or cold.
Figures from the Australian Government’s YourHome glazing guide show the size of the gap. YourHome lists a single glazed aluminium window at a U-value of 6.9, where a U-value measures how easily heat passes through and a lower number insulates better. A double glazed timber or uPVC window with a 6 mm cavity scores 3.0, which means about 57% less heat flow. YourHome also estimates that up to 87% of a home’s heat gain happens through its windows, which matters in a city that averaged 26.4 days a year above 35°C between 1994 and 2022, according to the Australia Institute.
Canon Double Glazing customers typically report 20% to 35% lower summer cooling costs after replacing single glazing, although orientation, shading and household habits all change the result. Homes still running old aluminium sliders can see the full upgrade path in the guide to replace single glazing with double glazing. Heat is only half of what a second pane keeps out, though, and the other half is often the reason people start looking at new windows in the first place.
Do Double Glazed Sliding Windows Reduce Noise?
Yes, double glazed sliding windows reduce outside noise compared with single glazing, and how much depends mostly on the glass gap and the seals. Two panes with a sealed gap block more sound than one pane, so traffic, voices and barking dogs become noticeably quieter. Any window that opens loses some performance through the gaps around its sash. A sliding sash has to glide past its frame, so those gaps rely on well-made seals to stay tight.
Independent research shows how much the seals matter. A National Research Council Canada building digest found that a well-weatherstripped opening window typically rates 3 to 5 points lower on the Sound Transmission Class (STC) scale than the same glass sealed shut. STC is a lab rating of how much sound a window blocks, similar to the Rw rating used in Australia. In an 18-window study for Canada Mortgage and Housing Corporation, one uPVC slider lost up to 8 STC points against sealed glazing while casement windows lost about 3, which the researchers suspected came from leaks at the sash joints. Yet an aluminium slider with a 108 mm air gap scored the study’s highest result of STC 41, so gap width and seal quality matter more than the opening style.
The same NRC digest found that laminated glass and two panes of different thicknesses both improve sound blocking, so the glass can be tuned for a noisy room. Bedrooms facing a highway, rail line or flight path may need that tuning or dedicated soundproof windows, and choosing the right pane is where it starts.
Glass, Lock and Screen Options for Sliding Windows
Sliding windows can be specified with different glass, locks, screens and finishes to suit each room. The right combination depends on which way the window faces, how private the room is and whether it sits on an upper floor. These are the main options to consider.
Glass Options
Low-E glass carries a thin metal oxide coating that reflects heat, which helps on west-facing windows that take the harsh afternoon sun. Tinted solar-control glass cuts glare and heat gain further, at the cost of some natural light. Laminated glass bonds two layers with a plastic interlayer, which improves noise reduction and holds together if broken. Obscure glass, which is textured or frosted, keeps bathrooms and toilets private without curtains. Glass in doors and low windows must also meet AS 1288, the Australian Standard for glass in buildings.
Locks and Security
Older sliders often relied on a single latch, which made them an easy target. Canon Double Glazing’s sliders use a four-point locking mechanism reinforced with steel, so the sash is held at several points along its height. The glass is also internally beaded, which means the strips holding the glass in place sit on the inside of the frame. That design stops the glass being removed from outside the house.
Flyscreens and Opening Restrictors
A flyscreen on a slider runs in its own track, so it stays in place while the sash opens and closes behind it. Upper-floor bedrooms need extra care. The Australian Building Codes Board requires bedroom windows to stop a 125 mm sphere from passing through where the floor below is more than 2 m above the ground. The restricting device or screen must resist an outward force of 250 N, unless the bottom of the opening sits at least 1.7 m above the floor.
Frame Colours and Finishes
Canon Double Glazing’s sliding windows come in Canon Pearl White as standard, along with two wood grain laminate finishes. A white uPVC frame reflects heat and suits most modern Perth homes. Wood grain laminates give the warmth of timber without the sanding and repainting that real timber needs. Matching the slider finish to nearby doors and windows keeps the outside of the house looking consistent.
Each of these choices adds a little to the price of the window. Size, though, usually has a far bigger effect on the final figure than any single option.
How Much Do Double Glazed Sliding Windows Cost in Perth?
A double glazed uPVC sliding window typically costs between $3,500 and $5,500 per opening in Perth, supplied and installed. A typical 3×2 home fitted out with double glazed windows runs from about $18,000 to $20,000, based on Canon Double Glazing’s current guide prices. The table below shows the main factors that move a quote up or down.
| Cost factor | What it changes |
|---|---|
| Window size | Larger sashes need more frame, more glass and stronger hardware. |
| Glass specification | Low-E, laminated, tinted or obscure glass costs more than clear glass. |
| Number of windows | Whole-home orders spread setup and installation costs across more openings. |
| Access | Second-storey or hard-to-reach openings take longer to remove and fit. |
| Finish | Wood grain laminates cost more than the standard white frame. |
The purchase price is only part of the picture, because better windows also change what a home spends on cooling. YourHome reports that energy-efficient windows can reduce peak cooling loads enough to cut the size of air conditioner a home needs by around 30%. A smaller system costs less to buy and less to run through a Perth summer. The double glazed sliding windows price page and the wider double glazed windows cost guide explain how quotes are put together. Getting the best value also means putting sliders where their strengths count most.
Where Sliding Windows Work Best in a Perth Home
Sliding windows work best where space is tight and a hinged sash would get in the way. In other rooms, an awning or casement window may suit the job better. These are the spots where sliders earn their place.
Kitchens and Above Benches
A hinged window above a kitchen bench is awkward to reach and can knock into taps or splashbacks when it opens. A slider needs only a sideways push, which makes it easy to open while leaning over a bench. It also keeps a wide, clear view of the backyard. Low-E or solar-control glass helps on a west-facing kitchen window that cops the afternoon sun.
Narrow Side Returns and Walkways
Many Perth homes have a narrow path running down the side of the house. An outward-opening window there would block the walkway or catch passers-by. A slider stays flat within the wall line, so the path stays clear whether the window is open or shut. That makes sliders the usual choice for laundries, studies and bedrooms that face a side return.
Bedrooms and Living Areas
Sliders give bedrooms and living areas wide glass, plenty of light and easy airflow on a summer evening. In upper-floor bedrooms, the opening must be restricted to meet the building code where the drop outside is more than 2 m. Bedrooms facing a busy road need extra attention to seals and glass, such as laminated panes or a wider gap.
Bathrooms and Rain-Exposed Walls
Bathrooms and walls that face the winter rain are often better served by an awning window. An awning sash hinges at the top, so it can stay open in light rain while the glass sheds water outward. A slider left open in the rain lets water in through the gap. Where a slider is used in a bathroom, obscure glass keeps the room private.
Most homes end up with a mix of window styles, chosen room by room. The practical questions that come with that mix are the ones homeowners raise most often.
Frequently Asked Questions About Double Glazed Sliding Windows
These are the questions Perth homeowners ask most often about double glazed sliding windows.
Can sliding windows be double glazed?
Yes. New uPVC sliding windows are built for double glazing from the start, with sashes deep enough to hold a full sealed unit. Existing aluminium sliders can sometimes take a thin retrofit unit, but their shallow channels limit the gap between the panes and the metal frame keeps conducting heat. Replacing the whole window usually gives a far better result.
What are the disadvantages of sliding windows?
Sliding windows open only about half their width, so they move less air than a casement window of the same size. The gaps around a sliding sash depend on good seals, and worn or poorly made seals let in more noise and draughts. The track also collects dust and leaves, so it needs regular cleaning to keep the sash running smoothly and the drainage holes clear.
Do double glazed sliding windows give enough airflow?
For most rooms, yes. A two-panel slider opens about half its width, which comfortably meets the building code minimum of 5% of a room’s floor area in a typical bedroom or living area. Placing sliders on opposite walls, or on the side that catches the afternoon sea breeze, increases the airflow further.
Are sliding windows good for small spaces?
Yes, sliding windows are one of the best choices for tight spaces. The sash moves sideways within the frame, so it needs no room to swing inside or outside. That suits narrow side paths, kitchen benches and rooms where furniture sits close to the wall.
Can I add flyscreens to a sliding window?
Yes. A flyscreen on a slider runs in its own track on the outside of the window, so it stays in place while the sash opens and closes. Upper-floor bedrooms may need a stronger security screen or a restrictor to meet the building code.
How long do double glazed sliding windows take to make?
Canon Double Glazing’s sliding windows are made to measure, with a lead time of about 6 to 8 weeks from the final measure to installation. Installation itself is quick. The team typically fits 3 to 4 windows a day and locks the house up before leaving.
Do sliding windows need much maintenance?
uPVC sliding windows need very little maintenance. Wipe the frame with warm soapy water, vacuum or brush the track every few months and keep the small drainage holes in the sill clear. Unlike timber, uPVC does not need sanding or repainting.
Choosing Double Glazed Sliding Windows for Your Perth Home
Double glazed sliding windows pair an easy sideways action with the comfort of a sealed unit in an insulated frame. You can use sliders where space is tight, choose casement or louvre windows where airflow matters most and specify the glass and seals carefully where noise is the main concern. Leaving old single glazed aluminium sliders in place means more summers of heat pouring through the glass and more winters of cold, draughty rooms. With Perth averaging more than 26 days above 35°C a year, the windows facing the afternoon sun carry most of that load.
Canon Double Glazing manufactures and installs uPVC double glazed sliding windows in-house across Perth, with steel-reinforced frames, four-point locking and a 10-year guarantee. You can book a free measure and quote or call (08) 9249 9974 to work out which style suits each window in your home.
