Loose Wire Underfloor Heating Guide (Electric UFH Systems)
Loose Wire Underfloor Heating Guide UK
Loose wire underfloor heating is one of the most flexible electric UFH options for tiled floors, awkward room layouts, bathrooms, en-suites and kitchens with lots of obstacles. Instead of using a fixed mesh mat, the heating cable is laid manually, making it easier to route around toilets, basins, shower trays, island units and irregular corners.
This guide explains how loose wire electric underfloor heating works, how Warmup and Flexel differ, which wattage suits different rooms, what build-up is usually required, what accessories you may need, and how loose wire compares with StickyMat & EcoFloor heating mats, DCM-PRO, foil heating and carbon film.
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Electric Underfloor Heating Guide
Electric UFH Systems Collection Guide
Electric Underfloor Heating Installation Guide
Underfloor Heating Insulation Guide
Underfloor Heating Compatibility Guide
StickyMat & EcoFloor Heating Mats Guide UK
DCM-PRO Guide
Recommended Loose Wire Underfloor Heating Products
A flexible electric heating cable system for tiled floors, bathrooms and awkward room layouts where manual routing is useful.
A flexible loose cable option from Flexel for irregular tiled rooms and buyers who want a choice of different output levels.
A thermostat with floor sensing helps manage comfort, reduce waste and protect the floor build-up over time.
Why Choose Loose Wire Underfloor Heating?
- Flexible layout around toilets, basins, kitchen units, corners and fixed furniture
- Very useful in irregular-shaped rooms where mats would need lots of turning and cutting
- Strong match for tiled and stone floors where good heat transfer matters
- More control over cable spacing than fixed mesh mats
- Often a better fit than heating mats when the room has many fixtures or awkward zones
If your floor finish is tile rather than screed, compare loose wire with DCM-PRO and StickyMat & EcoFloor heating mats. If your final floor will be laminate or engineered wood instead, loose wire is usually not the natural starting point, and foil heating or carbon film will usually make more sense.
Typical Loose Wire Build-Up
The floor should be dry, sound, level and suitable for tiling.
Insulation reduces heat loss into the subfloor and usually improves warm-up times.
The cable is positioned manually at the required spacing around the free floor area.
The cable is covered with adhesive or levelling compound before the tile finish is installed.
Loose Wire vs StickyMat & EcoFloor Heating Mats
| Feature | Loose Wire | StickyMat & EcoFloor Heating Mats |
|---|---|---|
| Installation speed | Usually slower | Usually faster |
| Layout flexibility | Very high | Moderate |
| Best for | Irregular rooms and obstacles | Regular-shaped rooms |
| Typical use | Bathrooms, en-suites, awkward kitchens | Standard bathrooms, kitchens and hallways |
| Main buyer reason | Route around fixtures neatly | Get the room fitted faster |
If the room has lots of fixtures such as a toilet, basin, shower tray, bath or awkward corners, loose wire is often easier to work with than a fixed heating mat.
Warmup vs Flexel Loose Wire Outputs
Loose wire systems are not all offered in the same way. Warmup and Flexel take slightly different approaches, so it helps to separate them clearly when choosing the best system for your room.
| Manufacturer | Typical Output | How It Works | Best For |
|---|---|---|---|
| Warmup | 150W/m² | Designed as a flexible loose-wire system where output is influenced by cable spacing | Well-insulated tiled rooms needing strong everyday performance |
| Flexel | 130W/m², 160W/m² and 200W/m² | Different cable outputs are offered for different room conditions and heat-loss levels | Buyers wanting a more fixed choice of output depending on room type |
Warmup Loose Wire: 150W/m² and Variable Cable Spacing
The Warmup Loose Wire system is rated at 150W/m², which is a sensible output for tiled floors because tiles are excellent conductors of heat. A higher wattage like 150W/m² helps the system warm the dense tile finish and adhesive layer more quickly, and it is often suitable as a primary heat source in well-insulated rooms.
Warmup’s loose wire system is also designed to provide extra flexibility for irregular room shapes. By adjusting the distance between the runs of cable, the installer can influence the effective heat output across the floor area.
- Standard spacing (150W/m²): the most common arrangement and generally suitable for primary heating in well-insulated rooms
- Minimum spacing: cable runs must be spaced at least 50mm apart to avoid overheating and possible cable damage
- Variable output: in higher heat-loss spaces, the cables can be positioned more closely to increase output within manufacturer guidance
Warmup loose wire is a strong choice where you want a flexible tiled-floor system with a standard 150W/m² setup for most rooms, but also the ability to adapt the layout to the room shape.
Flexel Loose Wire: 130W/m², 160W/m² and 200W/m²
Flexel offers a broader range of fixed output levels, which helps buyers match the cable more closely to the room conditions.
| Flexel Output | Best For | Typical Use | Buyer Notes |
|---|---|---|---|
| 130W/m² | Well-insulated internal rooms | Kitchens, bathrooms and general living spaces in efficient modern homes | A balanced choice where you want comfortable floor warming and sensible energy use. |
| 160W/m² | Higher-performance internal use | Tile or stone floors, especially over concrete bases where faster heat-up is useful | Often recommended where heat loss is a little higher or where you want a quicker response. |
| 200W/m² | High heat-loss areas | Conservatories, sunrooms and rooms with large glazed areas | Designed for more demanding spaces where heat loss is significantly higher than a standard internal room. |
Choose the output to suit the room, not just the product. A standard internal room often suits a lower or mid output, while colder, more exposed or heavily glazed rooms may need something stronger.
Thermostats, Insulation and Running Cost Context
A thermostat with a floor sensor is one of the most important parts of a successful loose wire installation. It helps manage comfort, reduces waste and protects the floor build-up from overheating. Smart or programmable thermostats are usually the better choice because they let you warm the room only when needed.
Insulation boards are also usually recommended beneath tiled electric systems because they reduce downward heat loss into the subfloor and help the room warm up faster. In real projects, insulation and control often make more difference to everyday comfort and running cost than buyers expect.
If you want a fuller explanation of controls, running costs and insulation choices, see our Thermostats Guide, Insulation Guide and Loose Wire Running Costs Guide.
Useful Loose Wire Accessories
Useful for helping secure cable positioning during loose cable installation.
Helps keep cable runs secure and maintain tidy installation spacing.
Usually recommended beneath loose wire systems to reduce downward heat loss and improve response time.
Recommended Loose Wire Build-Up
| Floor Finish | Typical Build-Up |
|---|---|
| Tiles / Stone | Subfloor → Insulation Boards → Loose Wire Cable → Flexible Tile Adhesive or Levelling Compound → Tile / Stone Finish |
For the full installation overview, read our Electric Underfloor Heating Installation Guide. If your project uses floating floor finishes instead, it is also worth checking the Overlay Board Guide because some foil-heating build-ups require additional protective layers.
When Loose Wire Is the Best Choice
- The room has an awkward shape
- There are lots of fixtures or permanent obstacles
- You want more control over cable spacing
- The final floor is tile or stone
- You are working in a bathroom, en-suite or irregular kitchen
Compare Systems
Buyer FAQs – Loose Wire Underfloor Heating
Is loose wire cheaper to buy than heating mats?
Usually yes on upfront product cost. Loose wire kits are often a little cheaper than the equivalent heating mat, but they normally take longer to install. If you are paying an installer by the hour, the labour cost can narrow or remove that saving.
What extra items should I budget for?
Besides the cable kit itself, most installations also need insulation boards, a thermostat, flexible tile adhesive or levelling compound, and sometimes fixing accessories such as tape or clips. That is why it helps to plan the full build-up rather than only the cable cost.
Can I save money by not using insulation?
No, not usually. Skipping insulation is often a false economy because more heat is lost into the subfloor, which can increase running costs and make the floor slower to warm up.
What is the SafetyNet cost benefit?
Warmup’s SafetyNet™ Installation Guarantee adds useful peace of mind. If the heating cable is accidentally damaged during installation, Warmup offers a replacement under that guarantee, which can save the cost of buying another kit.
Does more wire mean higher bills?
Not necessarily. A higher output or closer cable spacing may heat the floor faster, but because the thermostat cycles the system on and off, the overall running cost can still remain sensible if the room is well insulated and controlled properly.
Should I buy a larger cable just in case?
No. Heating cable must never be cut to fit. Always size the cable to the free floor area and exclude fixed furniture, baths, kitchen units and other permanent obstacles.
Is it cheaper to leave it on low all day?
Generally no. Loose wire systems are usually more economical when controlled by a smart or programmable thermostat so they heat the room only when needed.
Is loose wire underfloor heating better than heating mats?
Loose wire is usually better for awkward room shapes because it offers much more layout flexibility. Heating mats are usually faster to install in standard-shaped rooms.
Can loose wire underfloor heating be installed under tiles?
Yes. Loose wire electric underfloor heating is commonly used beneath ceramic, porcelain and stone floors.
Do I need insulation boards with loose wire heating?
In most cases, yes. Insulation boards help reduce heat loss into the subfloor and usually improve warm-up time and overall efficiency.
What wattage loose wire heating should I choose?
That depends on the manufacturer and the room. Warmup is commonly configured around 150W/m², while Flexel offers 130W/m², 160W/m² and 200W/m² options for different room conditions and heat-loss levels.
Is loose wire good for bathrooms?
Yes. Loose wire is often an excellent option for bathrooms because it can be routed around toilets, basins and other awkward fixtures.
What happens if I accidentally damage the cable during installation?
Warmup Loose Wire includes the SafetyNet™ Installation Guarantee. If the wire is accidentally damaged before tiling, Warmup offers a replacement under that guarantee.
Is a self-levelling screed always required?
No. One of the benefits of loose wire systems is that they can often be installed directly within the tile adhesive layer, depending on the build-up and tile specification.
How do I calculate how much cable I need?
You should aim to cover approximately 90–95% of your free floor area, excluding fixed units such as baths or kitchen cupboards. Never cut or shorten the heating cable. If you have excess cable, the spacing between runs must be adjusted within the manufacturer’s guidance.
Do I need to use a primer?
If laying directly onto plywood or concrete, primer is usually required before installation. If you are using suitable insulated tile backer boards, primer may not be needed in the same way because the board surface is already intended for adhesive-based tiling systems.
What warranty do these systems have?
Flexel offers a 20-year warranty on EcoFlex systems, while Warmup offers a lifetime manufacturer’s warranty on the DWS cable when registered within the required period.
Related Guides
Loose Wire Running Costs Guide
Electric Underfloor Heating Installation Guide
Electric Underfloor Heating Guide
Best Electric UFH Systems Buyer Guide
Underfloor Heating Thermostats Guide
Underfloor Heating Insulation Guide
Carbon Neutral Heating Guide
Ready to buy? Start with Warmup Undertile Loose Wire or EcoFlex Loose Cable, then add the correct insulation boards, a suitable thermostat, and any required fixing accessories to complete your tiled floor build-up properly.