The building, and what it does to the job
In Holborn, flats outnumber houses by a wide margin. A long carry is booked as a two-man job from the outset, not upgraded on the doorstep. The day is planned to the stock, not to a standard slot.
The communal entrance is a single leaf on a strong closer, and it has to be held by a person rather than a wedge while a piece goes through. Fixings into concrete go in with proper anchors, and the dust is contained rather than swept up afterwards. The building moved decades ago and the fit allows for it.
A live soil stack cannot be chased back into the wall, so the depth it steals is permanent and the run is planned around it rather than through it. We would rather find it at template than on the morning, which is why the templater looks behind the units. The alcove was never square and it still is not.
