Underfloor heating
Pressure Testing UFH Pipework Before the Screed Pour
A pressure test confirms the pipe network is sound before it's permanently covered, avoiding costly breakout if a leak is found later.
Ready for pour day?
Confirm your pressure test is in place and we'll get your pour booked in.
Or call our landline on 01392 237700
Once screed is poured over UFH pipework, any leak becomes far more difficult and expensive to find and repair. A pressure test carried out and held immediately before the pour is one of the simplest and most effective ways to catch a fault while it's still accessible.
As screeders, we typically won't pump over pipework without confirmation that this test has been carried out and held.
Testing is typically carried out hydraulically, with the circuit filled and pressurised to a level comfortably above normal operating pressure, though some installers use an air test at an early stage before water is introduced to the system. Either method should be followed by a documented hold period during which the gauge reading is checked for any drop.
Pressure Testing Before Pour — the points that decide it
- Pipework is usually pressurised with water or air to a level above normal operating pressure
- Pressure should be held and monitored for a set period, with any drop investigated before proceeding
- Testing should be carried out and witnessed before the screeding contractor arrives to pour
- Sign-off or a test certificate provides a record in case any dispute arises later
- The pressure should typically be maintained during the pour itself, not just before it starts
- A drop in pressure during the pour is a reason to stop and investigate rather than continue pumping
- Hydraulic testing with water is the most common method, though an early-stage air test is sometimes used before commissioning fluid is introduced
- A typical hold period runs for several hours, with the gauge checked at intervals rather than only at the start and end
- Ambient temperature changes during a long hold can cause small, non-leak-related pressure fluctuations worth accounting for when reading results
Why the test needs to be held during the pour
Testing before the pour confirms the system was sound at that moment, but maintaining pressure throughout pumping gives ongoing reassurance that nothing has been disturbed by the weight or flow of the screed. Many screeding contractors will ask to see the pipework holding pressure on the day before starting work.
What happens if pressure drops during the pour
A pressure drop during pumping is a signal to stop immediately and investigate, since continuing to pour over a leaking pipe could bury a fault that's then very difficult to locate and repair. This is a rare but serious situation, and having a clear responsibility split agreed beforehand between the UFH installer and screeder helps it be handled quickly.
Reading results correctly
A pressure gauge reading can shift slightly with ambient temperature changes even on a sound system, since the fluid inside expands and contracts. Distinguishing this from a genuine leak means checking the trend over the whole hold period rather than reacting to a single reading, and comparing conditions at the start and end of the test.
Documentation as a practical safeguard
A simple signed test certificate, noting the test pressure, hold duration and result, gives both the screeding contractor and the client a clear record that the system was sound immediately before pouring. This is a low-effort step that avoids ambiguity if a dispute arises later about when a fault might have occurred.
Coordinating testing with manifold commissioning
Pressure testing is normally carried out on the pipe loops before the manifold's flow and return connections are finally dressed and the cabinet closed up, giving clear access to check every joint for signs of a leak before it becomes hidden behind the finished cabinet.
Any adjustment to manifold pipework after a successful test, however minor, is generally followed by a further check of that connection, since even a small disturbance to a fitting can be enough to introduce a leak that wasn't present during the original test.
Common causes of a failed pressure test
Most failed tests trace back to a fitting that wasn't fully home, a small puncture from a sharp edge during first fix, or a loop that was damaged before pipe fixing was complete, rather than a fault with the pipe material itself.
Isolating the affected loop and retesting the remaining circuits individually is usually quicker than assuming the whole system needs re-checking, and it narrows down where the fault sits before any screed work is booked in.
Ready for pour day?
Confirm your pressure test is in place and we'll get your pour booked in.
Or call our landline on 01392 237700
Pressure Testing Before Pour — your questions
In short
A pressure test confirms the pipe network is sound before it's permanently covered, avoiding costly breakout if a leak is found later.
Where to look next
Ready for pour day?
Confirm your pressure test is in place and we'll get your pour booked in.