Bi-fold vs lift-slide: choosing the terrace opening
Bi-fold and lift-slide answer the same brief — a wall that opens to the terrace — from opposite directions. Bi-fold folds the leaves into a stack and clears almost the whole width; lift-slide lifts the leaves onto a bearing and slides them past each other, keeping the frame line straight and the operation one-handed. The choice turns on the stack position, the threshold detail and how the room is used, and both run on our 70 mm thermal-break platform.
What each opening actually does
Bi-fold (BF-40) folds panels on a running track — leaves to 1,000 mm, stacked to the side or into a corner, clearing most of the structural bay. The trade is the stack: the folded leaves occupy floor space at one end, and the track and the stack need room the elevation has to give. Lift-slide (LS-60) lifts each leaf onto a bearing and slides it behind its neighbour, so a three- or four-leaf unit opens to a 6 m walk-through with no stack on the floor and one-hand operation across the whole run.
The threshold decides a lot
Both lines can be specified barrier-free, but the details differ. The lift-slide runs a flush threshold with the track recessed into the floor build-up, which is the detail that passes an access review; the bi-fold carries a bottom-running track that the threshold detail has to reconcile with the drainage plane. On a project that has to stay step-free, that is often the deciding line.
Where each wins
- Bi-fold: courtyard and pool-side walls where a folded stack sits naturally; openings that want almost the full bay clear; elevations where the corner is a design feature and the stack can live there.
- Lift-slide: living-room walls to a terrace where the floor must stay clear; barrier-free access; wide units (three to four leaves, to 6–7.2 m clear) operated one-handed; elevations that want the frame line kept straight.
- Both: the same laminated or low-E IGU logic, and both take the impact or cyclone build where the wind zone or the coastal code requires it.
What to put on the schedule
- The stack position for a bi-fold — side, corner or both ends — because it moves the frame and the shop drawings.
- The clear-opening width and the threshold detail (flush or standard), per position.
- The glazing per leaf, because the bearing schedule on a lift-slide scales with pane weight.
- The wind or impact case if coastal — the bearing and rail upgrade is a line item, not a default.
Questions
Lift-slide. The flush threshold and the continuous gasket line seal better in driven rain, which is why the exposed coastal elevations usually run lift-slide and the sheltered courtyard runs bi-fold.