Choosing window opening styles for double glazing, room by room

Start with how each window is used, not how it looks

When people replace windows they often keep whatever opening style was there before, simply because nobody asked. That is a missed chance. A window that has annoyed you for years, the one you cannot reach over the sink, the bedroom slider that catches on its track, the casement that bangs against the pergola post, can often be made in a different style when the frame is replaced.

The useful question for each opening is practical. Who opens it, how often, and from where? What is directly inside and directly outside it? Does it need to give air in poor weather, or only on nice days? How will the outside of the glass be cleaned? Answer those for each room and the right style is usually obvious. The glass make-up is a separate decision, covered in the guides to energy efficient glass and privacy glass and daylight.

If your project is a retrofit that keeps the existing frames, the opening style mostly stays as it is, because the new sealed units go into the sashes you already have. Changing style generally means replacing the frame. That is worth knowing early, because it can decide whether a particular opening is quoted as retrofit or replacement.

The main opening styles and what each one asks of the room

Each style has a way of moving that brings its own needs. Think about the space the sash moves through and the part of the frame your hand has to reach.

• Awning. Hinged at the top and pushed out at the bottom, usually with a chain winder or a stay. It projects outside when open, and the opening sits under the sash.
• Casement. Hinged at the side and swings outward like a door. It opens fully and can catch a passing breeze, but it needs clear space outside for the swing.
• Sliding. One sash slides past another on a track. Nothing projects inside or out, but only part of the window area opens at once, and the track needs to stay clean to run smoothly.
• Double hung. Sashes slide up and down. It suits some older house styles and keeps the outside clear, but raising a heavy lower sash takes effort.
• Tilt and turn. One handle either tilts the top of the sash inward for ventilation, or swings the whole sash inward like a door. It needs clear space inside the room when turned.
• Fixed. Does not open. It gives the most glass for the frame and has no moving parts, but provides no ventilation.

Many windows combine these. A wide living room opening might be a fixed centre pane with an awning below or casements either side. A combination lets you keep a clear view while still getting air where you need it.

Reach and operation: the problem nobody tests in the showroom

A window can perform well thermally yet be awkward for its regular user to open. Test the operating action alongside the glass and frame specification. Kitchen windows over a deep bench and bathroom windows over a bath are the usual culprits, because you are leaning forward with your arm extended and cannot push or pull with much force.

Sliders and double hung windows depend on pushing or lifting the sash itself. A double glazed sash is usually heavier than a comparable single glazed design, although actual weight depends on glass thickness, sash size and frame construction. Its hardware must suit the quoted assembly. Good rollers and balances make a big difference, but at full stretch over a bench even a well made slider can be hard work. Winder operated awnings and casements move the effort to a handle near the bottom of the frame, which is often easier to reach and turn.

Consider who in the house needs to use the window. Someone with limited grip or shoulder movement may find a lever handle easier than a small winder knob, or the other way around. Where you can, try the actual hardware on a display sample at the height you will use it. If that is not possible, ask the supplier what winder, handle and roller options are available for the range being quoted.

Locks deserve the same attention. A lock that is hard to reach on a high sash tends to be left open. Ask where each lock sits on the frame, whether it is keyed, and how it works with the handle you have chosen.

Inside and outside clearance

Every opening style uses space somewhere. Outward opening windows use space outside, and inward opening windows use space inside. Before choosing, walk around the house and note what sits on either side of each opening.

Outside, look for paths, side passages, decks, pergola posts, downpipes, hose taps, gas meters and plants. A casement or large awning that opens across a side passage can catch someone walking past, and one that opens against a pergola post will never open fully. Ask how far each outward opening sash projects and whether a stay can limit it.

Inside, look for bedheads, desks, couches, kitchen taps, benchtop appliances, towel rails and window furnishings. The turn position of a tilt and turn window swings the sash into the room, so anything in that arc has to move whenever you want to open fully. Handles and winders also project a little, and they can clash with blinds or shutters that sit close to the glass. The guide to blinds, screens and handle clearance covers that in detail.

Sliding and double hung windows avoid most of these conflicts, which is why they are common beside paths and in tight rooms. The trade-off is that they open only part of the window area at a time.

Ventilation and weather

How a window ventilates depends on where the opening sits and how large it is. A casement swung wide can scoop a breeze that runs along the wall. A slider opens a vertical slot that lets air move in and out at the same time. An awning opens at the bottom, which suits bathrooms, laundries and kitchens where you want steady air without a wide opening.

An awning projects outward over the gap beneath it. A tilt-and-turn window instead creates an opening at the top when its sash tilts inward, as shown in REHAU's explanation of tilt-and-turn operation. Neither description establishes rain protection while open. Exposure, wind and the exact hardware matter. Ask when the supplier requires the window to be closed, including when you leave the room unattended.

Cross ventilation needs openings on more than one side of a room or house. If you are replacing only some windows, check that you are not accidentally removing the opening that made a room pleasant on a warm evening, for example by making a window fixed to save cost.

Screens affect this decision too. Outward opening windows are usually screened on the inside, and inward opening windows on the outside. Where the screen goes changes how you reach the handle and how easy the window is to clean.

Cleaning and upkeep over the years

Ground floor windows can be cleaned from outside, so opening style matters less. Upstairs is different. Think about how the outer face of each upper window will be cleaned using a method that avoids leaning out or improvised access at height. Tilt and turn windows and some casement hinges let you reach the outer glass from inside. Fixed upper windows need outside access or a cleaning service.

Sliding windows collect grit in their tracks, and dirty tracks make heavy double glazed sashes harder to move. Awnings and casements have hinges and winders that benefit from occasional attention. The maintenance guide covers routine care. When comparing styles, ask the supplier what routine care each style needs and whether sashes can be removed for cleaning. Removing a double glazed sash is a job for someone trained, because it is heavy and the glass must be supported properly.

Children, upper floors and opening limits

Openable windows in bedrooms and on upper floors need particular thought when young children live in or visit the house. The National Construction Code includes provisions for protecting certain openable windows to reduce the risk of falls, and the Australian Building Codes Board explains them in its advisory note on openable windows.

Whether and how those provisions apply to your project depends on the building work involved, so ask your installer, and if needed your building surveyor, what is required for each upstairs or bedroom opening. Do not try to adjust or remove restrictors or stays yourself to make a window open wider. If a window is limited in a way that makes it hard to use, raise it with the supplier, who can explain the options that keep the protection in place.

Opening style can help here. An awning or a tilt position gives ventilation through a small opening without the sash standing wide open. A fixed lower pane with an opening section above may be worth discussing, but opening style alone does not establish fall protection. Confirm the actual layout, opening limits and required protective hardware with the installer or surveyor.

Glazed doors follow the same logic

Glazed doors to decks and courtyards come in similar families. Sliding doors keep the floor space clear on both sides and are the usual choice where furniture sits close to the glass. Hinged doors, single or in pairs, open a clear gap but need a swing area, and outward opening doors need a clear landing outside. Stacking and bifold doors open a wide section of wall, but the folded panels take up space at one or both ends when open.

A double glazed door panel is usually heavier than a comparable single glazed design. Glass thickness, panel size and frame construction determine the actual weight, so the rollers, hinges and tracks must be rated for the quoted assembly. Ask what hardware is specified for each door and how the threshold is designed, because the threshold affects both weather sealing and how easy the door is to step over or wheel something across. If you use a screen door, confirm that the new frame has a place for it.

The same questions apply as for windows: who uses the door, what is on either side of it, and how often it stays open. A door that stays shut all winter and open all summer suits a different design from a door that is opened twenty times a day by children and a dog. The double glazed doors page covers the door options we work with.

Hypothetical example: one house, four different answers

Consider a two storey house having its window frames and glazing replaced. The kitchen window sits behind a deep bench and a tap, so the owners choose an awning with a chain winder near the sill, which they can reach without leaning across the sink. The side of the house has a narrow passage to the bins, so the laundry and bathroom windows along it are sliders that keep the path clear.

The family room faces the garden with nothing close outside, so it has a wide fixed centre with casements either side for breezes on summer evenings. Upstairs, the children's bedrooms use awnings with stays that limit the opening, and the main bedroom uses tilt and turn so the outer glass can be reached for cleaning, with the bed moved a little to clear the swing.

None of those choices is about the glass. They come from walking around the house and asking how each window is used. Doing that before the measure means the quote describes the windows you actually want, rather than copies of the ones you have.