Bifolding Door questions answered in plain English

In thermally broken aluminium, a 3-panel bifold door (2.4m–3.0m) costs €3,600 to €5,800 supplied and fitted, a 4-panel set (3.2m–4.0m) is €4,800 to €7,600, a 5-panel set (4.2m–5.0m) is €6,000 to €9,400, and a 6-panel set (5.2m–6.0m) is €7,200 to €11,500. Timber alu-clad frames run from €4,800 to €7,400 for 3 panels up to €9,600 to €14,200 for 6 panels.

Widening an existing rear window or standard 1.8m patio door opening—including propping the masonry, installing an RSJ structural steel lintel on concrete padstones, removing the masonry below, and plastering the reveals—typically adds €1,800 to €3,500.

Modern bottom-rolling aluminium and alu-clad bifold doors tested to BS 6375 / EN 12208 achieve Class 4 air permeability and 600 Pa water tightness when fitted with a weathered threshold or a recessed flush track paired with an external ACO slot drain.

A traffic door (or lead door) is a single hinged panel built into the bifold run with its own lever handle and multi-point lock. It lets you nip out to the garden on a wet Tuesday morning like a normal back door without folding back the whole stack.

An odd number of panels folding in one direction (such as 3+0 or 5+0) or an even number split into a 3+1 configuration gives you a hinged traffic door. Four panels folding all one way (4+0) cannot have a swinging traffic door on the lead end because the end leaf pivots directly off the jamb.

When bifold doors are supplied and fitted together by the installation company on a residential home, the entire package qualifies for Ireland's reduced 13.5% VAT rate (subject to Revenue's two-thirds rule), rather than 23% supply-only VAT.

Not when built from thermally broken aluminium with polyamide insulation strips, double or triple low-E argon toughened glass, continuous EPDM compression gaskets and a rebated weathered threshold (achieving whole-door Uw values of 1.0 to 1.4 W/m²K).

An odd number of panels sliding to one side (3+0 or 5+0) allows the end sash to work like a normal hinged back door with a lever handle for letting the dog out or taking bins out, whereas an even number sliding one way has no independent hinged leaf unless split 3+1.

Yes, on sheltered rear gardens or covered verandas where an external ACO linear drainage channel is installed right outside the recessed floor track. On exposed west-coast or hilltop gardens, a 15mm–25mm weathered rebated lip is safer against driving rain.

Individual aluminium bifold sashes are normally manufactured between 800mm and 1,200mm wide (most commonly 900mm to 1,000mm), keeping each leaf rigid, light on its bottom rollers and compact when folded back.

Yes — magnetic or cordless slider blinds can be hermetically sealed inside the 20mm–27mm cavity of double-glazed toughened units so they never gather dust or bang when the doors fold.

Once the structural opening is laser-measured at survey, factory fabrication in your chosen RAL colour takes 3 to 5 weeks, and fitting into a prepared opening takes 1 day (or 3 to 4 days if knocking through a solid wall with an RSJ steel beam).