Pouring level on a hillside: gradient, pump siting and datums in Christow

Liquid screed is self-levelling across the area it is poured into, but that levelling happens relative to the datum it is poured to, not relative to the ground the building sits on. If the sub-floor beneath the screed has been left with an unintended fall, or if different rooms have been brought to different levels by mistake, the screed will faithfully reproduce that in a level topping rather than fix it.

This is why a site visit on a hillside plot needs to check sub-floor levels with a level or laser rather than by eye, and why any discrepancy needs resolving with the groundworks or insulation contractor before the pour is booked, not discovered on the day.

Where the wagon has to stand below the floor level being poured, or above it, the pump has to work against or with gravity over the hose run, and that changes what hose length and pump setup are workable. A standing point on a lower part of a sloping plot, with the floor itself higher up, is a different pumping problem to a standing point above a floor that sits in a dug-out or lower level.

Working out roughly where the wagon can realistically stand, and measuring the vertical rise or fall to the pour area alongside the horizontal hose run, gives a much clearer picture than treating the job as if it were on flat ground.

Where a building steps down a slope, each level is generally better treated as its own pour with its own edge restraint, rather than trying to run one continuous screed across a change in level. This keeps each area level to its own correct datum and avoids the practical difficulty of forming and holding a step within a still-flowing liquid screed.

Door thresholds and internal steps between levels also need their finished floor levels agreed in advance, since a screed that is level within its own room but not coordinated with the room next to it creates a mismatch at the threshold that is far harder to correct after the fact.

It is not only the floor that needs a level reference on a sloping plot — the ground the wagon itself stands on matters too, since outriggers or stabilisers generally need a reasonably level, firm base to sit safely, and a wagon parked across even a modest cross-fall can be more limited in what it can safely do. Checking the proposed standing area with the same care as the floor levels avoids finding this out only once the wagon has arrived.

Where the only available standing space does have a noticeable slope, it is worth raising this at the quotation stage so it can be planned around, whether that means choosing a different standing point further from the property or accepting a longer hose run in exchange for firmer, more level ground.