Planning a rear extension or kitchen-diner refurbishment? You'll quickly face the bifold-vs-sliding question. Both create stunning openings to the garden, but they're designed for different things. Choose wrong and you'll regret it for 30 years.
Maximum opening width
Bifolds win on percentage opening. A 4m bifold can open about 90% of the aperture (panels concertina to one or both sides). A 4m slider with a 2-track configuration opens 50% (one panel slides behind another). A 3-track slider can reach 65% opening but adds frame complexity.
Sightlines when closed
Sliders win decisively. A 4m slider can have just two 25mm vertical mullions visible; a 4m bifold has 5-6 vertical mullions (one per panel) plus floor and head tracks. When closed, sliders look like glass walls; bifolds look like a row of doors.
Weather resistance
Sliders win. Modern lift-and-slide patio doors achieve Class 9A water tightness — significantly better than bifold doors (typically Class 6A or 7A). For exposed sites or houses with very wet weather, sliders are more reliable.
Threshold options
Bifolds offer better flush-threshold options for wheelchair-accessible designs and seamless indoor-outdoor flow. Sliders typically require a 30-50mm threshold step or sill — flush options exist but are more complex and expensive.
Cost
Comparable cost per metre. A 4m × 2.1m premium aluminium bifold: £8,000-£12,000 installed. A 4m × 2.1m premium aluminium slider: £8,000-£13,000 installed. Sliders tend to be slightly more expensive for the same opening width.
Lifestyle fit
Choose bifolds if: you regularly entertain outdoors, you want the maximum possible opening for parties and gatherings, you want a wheelchair-accessible flush threshold, and you value drama and architectural statement. Choose sliders if: you spend more time looking at the garden than walking into it, you live in an exposed weather location, you want slim sightlines and minimal frame interruption, and you have a more refined aesthetic preference.
Get help choosing
We supply both Origin, Smart Systems and Reynaers bifolds and sliders. Free survey and comparison quote — call 0800 088 6341.
Need help with your glazing project? S&K Glazing offers free surveys and fixed-price quotes across the UK. Call 0800 088 6341, message us on WhatsApp at 07830 175306, or request a quote online.