Correct cable selected
Check the model, output, cable length and intended floor construction against the project design.
Electric underfloor heating installation
How to Install In-Screed Underfloor Heating Cable
Set out the cable accurately, protect it during the screed pour and keep a complete test record at every stage.
In-screed cable forms part of the floor construction. The product design, insulation, fixing method, screed specification and commissioning sequence must therefore be agreed before work begins.
PREPARATION
Before You Start
Confirm the design, floor build-up and electrical plan before the cable is unrolled or fixed.
Heated area marked
Exclude permanent floor-level units and other areas where heat cannot dissipate safely.
Subfloor approved
Confirm it is sound, clean, dry and prepared for the specified fixing and covering materials.
Electrical route agreed
Confirm supply, RCD protection, load, thermostat, sensor and cold-tail routes before covering.
Test equipment available
Arrange the required resistance and insulation tests at every specified stage.
Installation record ready
Keep the product label, readings, plan and photographs for support and warranty records.
INSTALLATION RECORD
Tests to Record
Record results before installation, after the cable is fixed and again after it has been covered. Compare each result with the product label and the tolerances in the supplied manual.
| Checkpoint | Cable resistance | Insulation resistance | Recorded by / date |
|---|---|---|---|
| Before installation | _____ Ω | _____ MΩ | ________________ |
| After the cable is fixed | _____ Ω | _____ MΩ | ________________ |
| After covering / before connection | _____ Ω | _____ MΩ | ________________ |
Before installation
- Cable resistance
- _____ Ω
- Insulation resistance
- _____ MΩ
- Recorded by / date
- ________________
After the cable is fixed
- Cable resistance
- _____ Ω
- Insulation resistance
- _____ MΩ
- Recorded by / date
- ________________
After covering / before connection
- Cable resistance
- _____ Ω
- Insulation resistance
- _____ MΩ
- Recorded by / date
- ________________
Step-by-Step Installation
Follow the supplied manual for the exact cable, fixing method, spacing, covering materials and electrical test requirements.
Confirm the complete floor design
Check the cable model and output against the room heat loss, available heated area, insulation, screed construction and final floor finish.
Coordinate the floor build-up
Agree the insulation, membranes, reinforcement, movement joints, cable layer and screed specification with the relevant project trades.
Mark the heated area and exclusions
Set out walls, permanent units, floor penetrations, joints and other areas the heating cable must avoid.
Plan the electrical routes
Confirm the supply, RCD protection, load, thermostat, cold-tail joint and sensor conduit positions before the cable is fixed.
Test the cable before laying
Record the required cable and insulation-resistance readings and compare them with the product label and supplied manual.
Install the approved fixing system
Secure rails, tape, mesh ties or the fixing method specified for the product and screed construction.
Lay the cable to the design
Maintain the approved spacing and bend radius. Keep cable runs clear of one another, movement joints and unapproved penetrations.
Install and protect the sensor
Place the floor sensor in a suitable conduit between parallel cable runs, positioned so it can be withdrawn and replaced.
Inspect, test and photograph
Check the complete layout, joints and fixings. Repeat the electrical tests and photograph the whole heated area before screeding.
Protect the cable during screeding
Control access and use the agreed placement method so tools, barrows, pumps, reinforcement and trades cannot move or damage the cable.
Test immediately after covering
Repeat and record the tests as soon as the screed work is complete. Investigate any change before the floor build-up continues.
Cure and commission gradually
Allow the screed and floor finish to cure fully, then follow the approved first-heating and commissioning procedure.
FINAL CHECK
Protect the Installation and Keep the Records
A complete as-built record protects the cable, supports the warranty and helps with any future floor work.
Product label and model
All three sets of test readings
As-built cable and sensor plan
Photographs before covering
Electrician certification and settings
Product and floor-finish instructions
IN-SCREED CABLE INSTALLATION ADVICE
Frequently Asked Questions
Answers to common questions before the cable is covered.
Can any electric cable be installed in screed?
No. Use only a cable specifically approved for the proposed screed construction and follow its current installation manual.
How deep should the cable be?
The required position and cover depend on the cable, screed type, structural build-up and floor finish. Use the approved system design and the screed and cable manufacturers’ instructions.
Should the cable be live during the screed pour?
No. Keep it electrically isolated. Use the required test equipment or monitoring device specified for the installation, and repeat the formal tests after covering.
When can an in-screed system be switched on?
Only after the screed and floor finish have completed their required cure periods. Commission gradually in accordance with the approved floor and heating instructions.