Verification
Specifying Levels and Datums for a Liquid Screed Floor
Finished floor level and datum specification tells the screed installer exactly what level to achieve, and needs to be clear, consistent and coordinated across the whole project.
Need levels coordinated for a liquid screed pour?
We can advise on level setting-out and datum coordination for liquid screed projects across Exeter and the South West.
Or call our landline on 01392 237700
A liquid screed installer works to a target finished floor level, and that level needs to be defined clearly against an agreed site datum before the pour begins. Ambiguity over levels — different datums used by different trades, or levels quoted inconsistently between drawings — is a common source of coordination problems that only become apparent once the floor is down.
Specifying levels properly means establishing a single, unambiguous site datum, transferring it accurately to level pins or laser reference points around the pour area, and checking it against adjoining structure, doorways and any existing finished floor levels it needs to match.
Because liquid screed is self-levelling within a bounded area, it will reliably reach a level set by properly placed level pins — the accuracy of the finished floor is therefore only as good as the accuracy of the levels transferred to those pins before the pour.
Levels & Datums — the points that decide it
- A single agreed site datum should be used consistently across all trades and drawings
- Level pins or laser references should be set out accurately before the pour, not estimated on the day
- Finished floor levels should be checked against door thresholds, adjoining rooms and existing structure
- Falls to drainage, where required, must be specified separately and clearly from the general level
- Multiple pours across a large floor plate should reference the same datum to avoid level mismatches
- Any change to specified levels during construction should be communicated to the screed installer in writing
- Finished level accuracy depends on the accuracy of level transfer, not on the screed's self-levelling properties alone
Setting out an accurate datum
The site datum should be established early and referenced consistently in drawings and instructions to every trade working on the floor build-up, including the screed installer. Level pins or laser reference points are then set from this datum immediately ahead of the pour, giving the installer a fixed and accurate target level.
Because a flowing screed will settle to a level surface within the pour area, any inaccuracy in the level pins themselves will be reproduced in the finished floor — the self-levelling nature of the material corrects for surface irregularity, not for an incorrectly set target level.
Coordinating levels across a project
On larger projects with multiple pour areas, it is important that every area references the same datum so that finished floor levels line up consistently at thresholds and between rooms. A level that is correct within one pour but inconsistent with an adjoining area still results in a mismatched floor.
Where falls are required, for example towards a drainage point in a wet area, these should be specified explicitly and separately from the general finished floor level, since a self-levelling screed will not introduce a fall unless one is deliberately built into the level pins or a screeded fall layer beneath it.
Timing the level check against the drying programme
A finished floor level check carried out immediately after the pour can be misleading, since a screed can settle very slightly as it dries and loses residual water.
Scheduling a level check once the floor has reached the manufacturer's minimum curing age gives a more reliable figure to compare against the specified datum.
Recording the datum check at practical completion
A level survey taken once the screed has reached its stated curing age should record deviation from the agreed datum in millimetres at each checked point, not a general impression of flatness.
Naming the surveyor and the date on that record gives a future fit-out contractor a fixed reference for the floor as handed over, rather than a level that has to be re-established from scratch.
Need levels coordinated for a liquid screed pour?
We can advise on level setting-out and datum coordination for liquid screed projects across Exeter and the South West.
Or call our landline on 01392 237700
Levels & Datums — your questions
In short
Finished floor level and datum specification tells the screed installer exactly what level to achieve, and needs to be clear, consistent and coordinated across the whole project.
Need levels coordinated for a liquid screed pour?
We can advise on level setting-out and datum coordination for liquid screed projects across Exeter and the South West.