External Bifold Doors

Yes — modern external bifolds are tested to BS 6375 Pt 1 (weathertightness) and Pt 2 (operation). Achieving Class 4 air permeability and the highest water-tightness rating requires properly specified seals, drainage, and a competent installation. Cheaper or poorly installed bifolds are the source of most weatherproofing complaints — the door itself can be excellent, but a 2mm gap in the sealing chain ruins the rating.

A correctly specified, correctly installed external bifold should not leak — but this is a real risk with poor installations. The two failure points are usually the threshold (where rainwater can pool if drainage is undersized) and the seals between panels (which degrade over time if low-quality EPDM is used). We use double-sealed thresholds with positive drainage, marine-grade EPDM, and 20,000-cycle-tested hardware to eliminate these risks.

Yes — low-threshold options give a near-flush transition between inside and outside, typically with a 5–10mm step rather than the traditional 50mm rebated threshold. This is ideal for level-access requirements, wheelchair use, and indoor-outdoor flowing schemes. The tradeoff is slightly reduced weatherproofing performance compared to a fully rebated threshold — Class 3 vs Class 4 — though for most UK locations this is academic.

Modern external bifolds use multi-point hook locks on every panel, anti-lift hinges, and toughened or laminated safety glass. PAS 24 certification (the security standard for Secured by Design and Approved Document Q) is available across our range. A PAS 24 bifold is as secure as any other modern external door — substantially more secure than the older single hinged doors most are replacing.

A typical 3–5 panel external bifold installation takes 1–2 days. This includes removing the existing door or window, preparing the opening (any necessary lintel work is normally separate), fitting the frame, installing the panels, fitting the threshold and seals, glazing-in the panels, and a full operational test. Larger or more complex installations (7-panel sets, corner configurations) can take 2–3 days.

Insurance providers typically don't differentiate between bifolds and other door types — what matters is the security specification. A PAS 24 certified bifold satisfies most insurance security clauses. Notify your insurer when changing external doors as a matter of good practice. Some policies require notification of any increase in glazed area, though this is unusual.