Underfloor heating
Commissioning and Heat-Up Regimes for UFH Screed
A gradual, staged heat-up allows a newly cured screed to adjust to temperature evenly, reducing the risk of thermal shock and cracking.
Commissioning is the process of bringing a UFH system up to operating temperature for the first time after the screed has had time to cure. It's generally carried out gradually rather than switching straight to full flow temperature, to let the floor adjust evenly.
The specific regime used should follow the screed manufacturer's guidance and the UFH designer's commissioning procedure for the system installed.
A typical staged regime might start at a low flow temperature for a set number of days before stepping up in defined increments toward the design flow temperature, with each step held long enough for the floor to stabilise before the next increase. The exact steps, hold periods and starting temperature should follow the screed manufacturer's published commissioning schedule for the specific product and depth installed.
Commissioning & Heat-Up Regimes — the points that decide it
- Commissioning typically begins only after the screed has reached an appropriate minimum age and moisture condition
- Flow temperature is usually raised in gradual steps over a period of days rather than immediately reaching full output
- A record of the commissioning process supports any warranty claims and future servicing
- Commissioning is often used as an opportunity to further reduce residual moisture before floor coverings are laid
- Manufacturer-specific commissioning guidance should always take precedence over generic industry timeframes
- Sudden large increases in flow temperature on a young screed can increase the risk of cracking
- A staged regime typically starts at a low flow temperature and steps up incrementally over several days
- Each temperature step is usually held long enough for the floor to stabilise before increasing further
- BS EN 1264 references commissioning and heating-up procedures that designers draw on alongside manufacturer guidance
Why a staged approach is used
Raising the temperature gradually allows moisture within the screed to move and evaporate steadily and lets the material expand evenly, reducing the risk of localised stress that a sudden jump to full temperature could cause. This staged approach is standard practice across most screed types used with UFH.
Commissioning and drying are related but distinct
Commissioning heat-up can assist with reducing residual moisture in the screed, but it isn't the same process as the initial natural or force drying period, and floor coverings shouldn't be scheduled based on commissioning alone without a proper moisture check.
A typical staged schedule in outline
While the specific figures always come from the manufacturer's datasheet, a staged regime commonly begins at a modest starting flow temperature held for a number of days, followed by incremental increases every day or two until the design flow temperature is reached and held. This gradual approach lets moisture migrate and the screed expand evenly rather than all at once.
Recording the commissioning process
Logging the date, flow temperature and duration at each step of the commissioning regime creates a simple record that's useful for warranty purposes and for anyone servicing the system later, particularly if a fault investigation ever needs to establish whether commissioning followed the recommended schedule.
Commissioning zone by zone
On a floor with multiple manifold zones, commissioning is sometimes carried out zone by zone rather than bringing the whole floor up to temperature simultaneously, particularly where rooms were poured at different times or have different screed depths.
This staggered approach lets each zone's heat-up follow a schedule appropriate to its own screed age and depth, rather than forcing a single timeline onto areas that cured at different rates.
Interaction with floor covering safety limits
Where floor coverings are already laid before commissioning, the heat-up regime needs to respect the covering's stated maximum surface temperature and rate of change alongside the screed manufacturer's schedule, since the two sets of guidance can occasionally differ and the more conservative one should generally be followed.
This is a further reason to keep commissioning records, since a documented heat-up regime provides evidence that both screed and covering guidance were respected if a covering-related query arises later.
In short
A gradual, staged heat-up allows a newly cured screed to adjust to temperature evenly, reducing the risk of thermal shock and cracking.
Planning your commissioning schedule
We can advise on timing between screed pour and commissioning as part of your project programme.
Or call our landline on 01392 237700
Commissioning & Heat-Up Regimes — your questions
Planning your commissioning schedule
We can advise on timing between screed pour and commissioning as part of your project programme.