Bi-Fold & Sliding Doors

Wide glazed openings that connect a new extension to the garden

Bi-fold and sliding doors are usually the single feature that most changes how an extension feels day to day — a wide, glazed opening connecting indoor and outdoor space — and getting the structural opening and installation right is what determines whether they operate smoothly for years or start sticking and dragging.

Bi-fold doors fold back in a concertina of individual panels, stacking neatly to one or both sides of the opening and giving the widest possible fully open aperture when required, which suits households wanting to genuinely open the whole wall to the garden. Sliding doors run large glazed panels along a track, offering a cleaner, more minimal look when closed and a slightly different balance of opening width versus glass area when partially or fully open — the right choice between the two comes down to how the doors will actually be used and the specific proportions of the opening. Whichever type is chosen, the opening they sit within is a significant structural element in its own right: a wide glazed opening needs a properly specified lintel or beam above it, sized by a structural engineer to safely carry the load previously supported by the wall being replaced, and the floor and threshold below need to be level and correctly detailed to avoid water ingress at the base of the doors, since this is one of the most common points where a poorly installed door system eventually leaks. Correct installation also means the frame is set truly level and square in the opening — doors that are even slightly out of true will bind, drag or fail to close and lock properly over time, which is one of the most common and entirely avoidable snagging issues on new extensions.