How factory-assembled sashes cut site labour
Factory-assembled means the sash leaves the line already glazed, hung and gasketed: the installer sets a finished unit into the frame instead of building one in the weather. The site saves the glazing, the gasket compression and the multi-point adjustment — the three operations that are hardest to quality-check on a roof or a fourth floor — and the container is loaded with a per-bay report and a packing list per crate that the site agent can claim against.
What the line actually assembles
The sash is built to the configured spec before it leaves: the IGU or laminated lite set and gasketed, the hinges and the multi-point engagement fitted and adjusted to the compressed measurement, the screens on the flush frame where the schedule has them. The quality gate is the same one the window line runs — a finished unit is checked as a unit, at bench height, under the line light, not at the opening in the afternoon. That is the difference the site feels: the adjustment that used to happen on the wall now happened at the bench.
What the site keeps doing
- Setting the frame square into the opening, to the fixings the drawing calls for.
- The weather seal at the wall junction — the building envelope, not the window.
- The threshold where the detail is site-side; the flush barrier-free line arrives integrated on the unit.
- Final check of the operation and the lock schedule, against the crate list.
How it packs, and what the agent gets
Factory-assembled sashes pack to roughly the same container count as flat-processed units, because the frame stack and the sash stack share the bay — the cost is in the care, not the volume. Loading is reported per bay, and the packing list runs per crate, which is what the site agent needs to claim the container, match the crates to the floor they belong on, and start setting the same day. The heavier lites — the impact laminated units and the 400 kg pivot leaf — travel crated to the same standard, with the handling marks the crane crew reads.
The lead-time picture
The assembly happens inside the quoted lead time, not on top of it: the standard lines run 30–40 days, the impact-rated schedules 40–55, and the timber-faced wood-aluminium at 40–50. A site that has budgeted for on-site glazing labour usually finds the schedule lands earlier than the flat-pack equivalent — the unit is ready to set the day it is ready to ship.
Questions
The unit price carries the bench work; the site labour saving usually exceeds it. On multi-storey work the delta is visible in the first week.