The short answer: choose a bifold when you want the whole opening clear and have room for the folded panels to stand outside, and choose a sliding or stacker door when you want big panes of glass, nothing folding out onto the deck, and a door you will open a little every day. The rest of this guide explains why, so you can test that answer against your own house.
How Each One Opens
A bifold door is a row of hinged panels that run on rollers in a bottom track; ours are bottom rolling. Pull the lead panel and the run folds like a concertina to one end, or splits to both. When it is open, the opening is clear from jamb to jamb.
A sliding door has one fixed panel and one that glides past it, so half the opening is clear. A stacker is a sliding door with more panels: three or four slide one behind another and stack behind a single fixed panel, which opens two-thirds or three-quarters of the wall. Both are on our sliding and stacker doors page.
The Space Either Side
This is the question that decides most jobs. Our bifolds open outward only, so the folded panels always stand on the deck side, never in the room, and they stack in one of two ways. At 90 degrees, they stand at right angles to the wall, projecting out by the width of a panel. With the foldback option, they fold right back against the cladding. On a deep deck either is no trouble. On a narrow balcony, beside a path, or where the barbecue and the outdoor table live next to the door, a stack standing at 90 degrees is in the way, and the foldback option is the one to ask us about.
A slider keeps every panel in the line of the wall. Nothing swings, nothing projects, and furniture can sit right up against the glass on both sides. That is why a stacker is usually the better answer for apartments, upper-storey balconies and tight courtyards.
The View When It Is Closed
A door is closed far more often than it is open, so look at it shut. A bifold has more panels for the same width, and every panel has its own frame, so there is more aluminium and less glass in the view. A stacker uses fewer, wider panels, so you look through larger uninterrupted panes. If the opening frames a view you want to see from the couch in winter, that favours the slider.
Everyday Use and Ventilation
Think about a weekday, not the summer party. With a slider you push one panel back as far as you like: a hand's width for air, or enough for the dog. Awning windows can be built into the same frame for air with the door shut.
A bifold is either folded or it is not. The fix is a traffic door, one panel hinged to swing on its own so you can step out without folding the run. It is an option on our bifolds, and it is worth asking any supplier whether theirs has one.
Glass, Weather and Security
Both types have the option of double or single glazing, with Low E glass and thermally broken frames available. Both lock at several points. Where they differ is tolerance: a bifold has more hinges, seals and moving joints, so it depends more on a dead level sill and a straight head. That is an installation matter rather than a product one, and it is why we fit our own. The systems we fabricate are designed and tested by OMEGA Windows and Doors for New Zealand conditions, and we specify the panel sizes to suit your site.
What Drives the Cost
We do not publish prices, because the size, the glass and the number of panels change them too much to be useful. As a guide to what moves the number: more panels mean more frame, more hardware and more labour, so for the same opening a bifold usually costs more than a stacker, and a two-panel slider is usually the most economical of the three. A wider opening in an existing wall also needs a new lintel, which is the builder's cost rather than ours. We are happy to quote the same opening both ways so you can compare.
A Quick Way to Decide
- Choose a bifold if the deck is deep, you entertain outdoors often, and you want the room and the deck to become one space.
- Choose a stacker if the view matters most, space is tight on either side, or you want a wide opening without a stack of panels.
- Choose a two-panel slider for an everyday door from a kitchen or bedroom, or where the budget is better spent on glass.
If you would like to see the difference rather than imagine it, build both in our 3D visualiser, open them, and look at where the panels end up.
Contact Us
Tell us the width of the opening and what it opens onto, or send the plans, and we will recommend a layout and quote it. Call 09 278 4089 or use the form below for a free measure and quote.
