Mat under tile vs. heating cable – which solution is better for your case
Underfloor heating mat vs. heating cable – which solution is better for your case
When a customer decides on electric underfloor heating, they quickly encounter two basic technical solutions: a heating mat (a mesh mat with an incorporated cable) and a loose heating cable. At first glance, it may seem like a marginal difference – after all, both are resistive cables that convert electrical energy into heat. In practice, however, this decision will affect not only the final result and installation comfort, but also the long-term functionality, cost, and flexibility of the entire system. Over the years I have worked in the field of heating technology, I have seen many installations where the customer chose the wrong product – not because they were incompetent, but because no one properly explained the difference and when each solution is really suitable.
In this article, we go into depth. We will explain the structural differences, compare both systems in terms of installation, costs, and suitability for different types of rooms, and show you specific practical scenarios where one solution clearly outperforms the other.
Structural difference: what is a mat and what is a loose cable
An electric underfloor heating mat is essentially a thin resistive cable that is factory-sewn or glued to a mesh fabric (glass fiber mesh) at precisely defined intervals – typically 8 to 10 cm between loops. The whole unit has a fixed width (most commonly 0.5 m) and is available in various lengths. This construction ensures that the power per m² is uniform and predictable, as the cable spacing is constant across the entire surface. Voltage and power are precisely set at the time of manufacturing.
A loose heating cable, on the other hand, is a simple resistive cable without a mesh carrier layer. It is delivered coiled on a spool or folded in spools and the installer lays it manually – either using mounting strips (fastening tapes) that are nailed into the screed, or directly into flexible adhesive. The spacing between loops is set by the installer, giving them flexibility – but also responsibility for the accuracy of the calculation.
From the perspective of the physical principle, both systems are very similar – they are based on resistive heating. The difference is therefore primarily in the installation, flexibility of shaping, and predictability of the result.
Thickness and floor height: a decisive factor that is rarely discussed
One of the most important aspects that significantly influences the decision is the thickness of the floor construction. A mat is extremely thin – typically 3 to 4 mm including the mesh. It is laid directly into flexible adhesive, which is applied to the subfloor or existing floor surface. The adhesive covers the mat, creates a tight layer, and is also a thermal transfer medium. The overall increase in floor height is therefore minimal – the entire construction adds only 5 to 8 mm.
A loose cable has a similar diameter (typically 4–6 mm), but requires a different approach to laying. In most cases, it is laid into anhydrite or cement-based screed at least 3–5 cm thick above the cable. This is a crucial difference. If you are renovating a bathroom in a panel building, where every centimeter of floor height is critical in terms of thresholds, doors, and adjacent floors in other rooms, the mat is clearly the right choice. If you are building a new structure and have enough space for a thick floor, a loose cable will give you more freedom.
When thickness is critical and when it is not
From practical experience, I know that in panel buildings, the height difference between the floor in the bathroom and the corridor is very small – sometimes only 10–15 mm. If you add a screed with a cable, you would have to raise the entire corridor as well, which is an investment several times greater than the underfloor heating itself. A mat elegantly solves this problem – it is laid into the adhesive and adds practically nothing to the thickness.
In a new construction with a concrete subfloor and a classic floor composition, the situation is different. There, a screed with a cable is a normal part of the composition and does not cause any problems. In addition, a loose cable in a screed has a better thermal storage capacity – the concrete mass stores heat and maintains the temperature longer after operation is interrupted.
Comparison of installation effort: where the mat wins and where it loses
A mat is designed to be installed by an experienced tiler or a technically skilled DIY enthusiast – of course, with the exception of the electrical connection, which must be done by an electrician with the appropriate license. The process is relatively straightforward: unrolling the mat, laying it on the subfloor, embedding the cold end of the cable into a groove in the wall, checking the resistance with a multimeter, and covering it with adhesive. The shape of the mat is fixed – you either use it in full, or you cut the mesh (not the cable) and rotate the mat, changing the direction of laying.
A loose cable gives the installer more freedom in shaping, but at the same time requires more expertise. The installer must correctly calculate the spacing between loops, ensure that the cable does not cross over itself anywhere (risk of overheating and failure), maintain the minimum bending radius, and evenly cover the entire surface. A faulty installation of a loose cable is much harder to correct than a mistake with a mat.
Economics: price of mat vs. cable in real installation
The mat is generally more expensive than the free cable itself – manufacturers charge a premium for the pre-prepared product. At first glance, the free cable thus appears more economical. However, it is necessary to include the total installation costs:
- Mat: product price + adhesive + possibly underlayment film + thermostat + electrician's work
- Free cable: cable price (lower) + fixing tapes or metal mesh + anhydrite mortar (material + professional work during casting) + screed + thermostat + electrician's work + longer technological pause for the mortar to dry
When you add up all the items, the free cable in a bathroom renovation will be more expensive than the mat – especially due to the mortar and waiting time. In a new building, where the mortar is part of the basic floor composition regardless of heating, the calculation is different and the cable can be more economical overall.
Concrete numbers: example of a 5 m² bathroom
Imagine a bathroom with an area of 5 m², where the actual heated area (after subtracting the bath, toilet, and cabinet) is about 3 m². For the mat, you would need, for example, HAKL electric floor heating mat under tiles, width 0.5 m, length 6 m, which covers 3 m² at a width of 0.5 m and a length of 6 m. You lay it directly into the adhesive, embed the thermostat sensor, and you are done in half a day. No mortar, no waiting time.
For a free cable on 3 m² at a power of 150 W/m², you need a cable with a total output of around 450 W. You embed it into the mortar, wait 4–6 weeks (depending on the thickness and type of mortar) for it to dry, then lay the tiles. The total time from start to a usable floor is significantly longer.
Mat for different types of rooms: where it makes sense and where it does not
The mat is primarily designed for installation under ceramic tiles or stone cladding. The adhesive into which the mat is laid is an ideal thermal transition medium – it directly transfers heat to the tiles without air gaps. This is an ideal combination for bathrooms, kitchens, corridors, and entrance halls.
Under wooden floors, cork, or thick layers of vinyl tiles, you generally do not use the mat – not because of the mat itself, but due to the thermal insulation properties of these materials, which limit heat transfer upwards. In exceptional cases, there are special mats certified for thin vinyl floors (LVT), but that is a separate topic.
Practical example: corridor with an irregular shape
In corridors with recesses, corners, and irregular shapes, the mat can be adapted by cutting the mesh fabric (note – never the cable itself!) and rotating another section by 180 degrees. This way, you can "fold" the mat into an L or U shape and cover an irregular layout. For very complex shapes (corridors with bends, space around the stairs), the free cable may offer more freedom – but only at the cost of a more complex installation and mortar.
If you are interested in this topic in more detail, please see our next article in the Knowledge Center: What dimensions and lengths of mats to choose for an irregular room shape – there you will find concrete calculation examples for L-shapes, T-shapes, and corridors with columns.
Power per square meter: how the mat and cable differ
A standard heating mat has a power of 150–160 W/m². This number is determined by the manufacturer and the installer cannot change it – the cable has a fixed total length and fixed resistance. If you want a different power density, you must choose a different mat (a different length = different total power for the same area).
The free cable allows you to adjust the power per m² by adjusting the spacing of the loops. If you want 100 W/m² (for example, for supplementary heating in a well-insulated room), you set a larger spacing. If you want 200 W/m² (primary heating in a poorly insulated house), you reduce the spacing. This flexibility is valuable when designing larger systems with different requirements for zones.
For standard home use – supplementary heating of the bathroom, floor heating in the kitchen, or comfortable heating of the hallway – a fixed power of 150 W/m² is completely sufficient and you don't need greater variability. You will appreciate this especially in projects with larger areas and different zones.
Variable mat lengths: what is available and what follows from it
One of the practical advantages of the heating mat system is that it is manufactured in standardized lengths, so you can easily choose the size closest to yours. On Atria.sk you will find, for example:
- HAKL mat 0.5 m × 2 m – area 1 m², ideal for small spaces, in front of the shower or sink
- HAKL mat 0.5 m × 5 m – area 2.5 m², suitable for a larger bathroom with a bathtub and shower
- HAKL mat 0.5 m × 6 m – area 3 m², a classic size for an apartment bathroom
- HAKL mat 0.5 m × 10 m – area 5 m², for larger bathrooms, hallways or a combination of multiple rooms
When choosing the length, one basic rule applies: the mat is not cut or spliced – the total cable length in the mat is precisely set for the given resistance and power. If you buy a mat that is too long and want to shorten it, you can only shorten the unused part of the mesh (simply roll it up or fold it outside the heated area, but the cable must be fully embedded in the adhesive). More on this topic can be found in the article Installation of electric floor heating mat step by step.
Thermostat and control: the same for both systems
From the perspective of the thermostat, there is no difference between the mat and the loose cable – both systems are connected in the same way. The thermostat measures the floor temperature via a sensor (NTC sensor), which is embedded in the floor construction in a protective tube, and turns the cable on or off based on the set value. The thermostat can be analog (knobs) or digital (display, weekly program, WiFi).
The only relevant parameter when choosing a thermostat is the maximum allowable current/power – standard thermostats are dimensioned for 16 A (3,600 W at 230 V). For larger areas with higher power, a thermostat with a higher rated current is required, or an external contactor. Details on setting and connecting the thermostat can be found in the article How to set and connect a digital thermostat to floor heating.
Safety and warranties: what to pay attention to when purchasing
For both types of products, it is important to verify that they have the appropriate certifications for use in wet areas (bathrooms are a special zone in terms of electrical safety). Electrical installations in bathrooms are subject to the STN 33 2000-7-701 standard, which defines zones and minimum requirements for protection against water and electric shock. Heating systems in bathrooms must be powered via a residual current device (RCD) with a rated tripping current of maximum 30 mA.
HAKL mat is a product from a verified European manufacturer with certification for use in bathrooms. In case of any doubts about the product's certification, always ask the seller for the relevant documents.
Another safety aspect is the coverage of the thermal sensor. The thermostat sensor must be stored in a protective tube closed on the cable side and open on the thermostat side – this allows for possible replacement without breaking the floor. Never allow the sensor to be permanently embedded in the adhesive without a tube.
Typical scenarios from practice: which solution I recommend and why
Scenario 1: Renovation of a bathroom in an apartment building, area 4 m²
The customer has a bathroom with original tiling on concrete. They want to preserve the threshold heights. Solution: a mat under new tiling, without screed. The entire installation takes one day, the electrician connects the thermostat and on the second day the bathroom is usable (the adhesive dries in 24–48 hours). A loose cable would not make sense here – raising the floor by 8–10 cm would prevent opening the doors and cause problems with thresholds.
Scenario 2: New build, kitchen and living room floor, area 30 m²
In a new build, the screed in the floor is automatic. A loose cable is a cheaper solution here – material costs for the cable are lower and you would pour the screed anyway. In addition, 30 m² of mat would be many pieces to coordinate, while one or two cables would cover the entire area. An advantage is also the better thermal storage – a thick concrete screed stores heat and the room cools down more slowly.
Scenario 3: Bathroom in a family house, primary heating (not supplementary)
If underfloor heating is to be the only heat source in the bathroom (no radiator, infrared heater or other system), you need to ensure sufficient power. With mats of fixed power 150 W/m² and a real heated area of 3–4 m², you get 450–600 W – this is fully sufficient for most bathrooms up to 8 m². For larger areas or worse thermal insulation, you may consider loose cable with higher power per m². For more on power sizing, see the article What power mat do I need per square meter of bathroom or living room?.
Scenario 4: Corridor 0.8 m × 4 m (L-shape)
A narrow corridor is a typical case where a 0.5 m wide mat fits perfectly. You lay it along the length of the corridor and across its full width (0.5 m mat + the rest covered by furniture or outside the zone). For an L-shape, you cut the grid and turn the mat. Loose cable would be unnecessarily complicated here – working with mortar in a narrow corridor is a logistical hassle and involves long waiting times.
Combining both systems: when it makes sense
In some projects, both systems are combined – a mat in the bathroom (renovation, thin construction) and loose cable in the living room with a new floor (new build, larger area). Each space gets the system that suits it best. Both systems can have separate thermostats on different circuits, or they can be connected to a central smart home control system.
If you are considering a larger installation with multiple zones and want to understand the overall system logic, we recommend starting with the articles How to choose an electric underfloor heating mat – power, dimensions and floor type and Underfloor heating in the bathroom – what to watch out for during installation under tiles.
Malfunctions and diagnostics: where the mat is more robust
In terms of long-term reliability, both systems are comparable – modern resistance cables have a lifespan of 20–30 years with proper installation. Most faults occur due to mechanical damage during installation (crossing the cable with wheelbarrows, piercing during tile laying, compression during late backfilling) or errors in connecting the cold end.
The mat has a slight advantage here – the grid-like carrier layer holds the cable in place during installation and offers some protection against mechanical displacement. Loose cable is more vulnerable during mortar work – workers may step on it, the cable may shift or bend beyond the critical radius.
If a fault occurs, diagnostics are similar for both systems – measuring resistance and insulation resistance with a multimeter and insulation tester. For more on fault diagnostics, read the article Common faults in electric underfloor heating and how to diagnose them.
Summary: decision table
| Criterion | Mat | Loose cable |
|---|---|---|
| Construction thickness | ✔ 5–8 mm | ✗ 50–80 mm |
| Installation complexity | ✔ Low | ✗ Medium–high |
| Time to usability | ✔ 1–2 days | ✗ 4–8 weeks |
| Material cost per m² | ✗ Higher | ✔ Lower |
| Power flexibility W/m² | ✗ Fixed (150 W/m²) | ✔ Variable |
| Shape flexibility | ✗ Limited | ✔ High |
| Suitability for renovations | ✔ Ideal | ✗ Complicated |
| Thermal mass | ✗ Small | ✔ Large (mortar) |
| Suitability for new builds | ✔ Yes | ✔ Ideal |
Frequently asked questions (FAQ)
Can I shorten the mat if it is longer than my area?
You cannot shorten the mat – more precisely, you must not shorten the heating cable, as this would change its resistance and overall power. You can cut the grid fabric (carrier mesh) – this allows you to change the laying direction of the mat and adapt it to an irregular room shape. The unnecessary part of the mesh is simply cut off, but the cable must remain in full length embedded in the adhesive or mortar. Never leave the cable hanging in the air or coiled without covering.
What if I need to cover a larger area than one mat?
The solution is simple – use two or more mats connected in parallel to the same thermostat (as long as the total power does not exceed its rated load). An alternative is a longer mat – for example, HAKL mat 0.5 m × 10 m covers 5 m² and is laid in two rows side by side. The thermostat must be sized for the total load. For larger areas, we always recommend performing a power calculation.
Is loose cable suitable for the bathroom, or only for living areas?
Loose cable is technically suitable for the bathroom as well, but the condition is proper certification for wet areas and installation in accordance with STN 33 2000-7-701. The practical disadvantage is different – mortar in the bathroom raises the floor level and complicates coordination with waste pipes, the bathtub and the shower area. From a practical point of view, the mat is clearly a more convenient solution for the bathroom.
Can the mat or cable damage the tiles?
Properly installed systems do not damage tiles. Problems arise if the tiles are improperly glued (air gaps under the tiles – the so-called "hollow sound" effect) or if the system is not equipped with a thermostat with a floor sensor and the maximum surface temperature is exceeded (usually 27–35 °C for living areas, 40 °C technically). Some tiles (especially natural stone) may be sensitive to temperature differences – always check the manufacturer's recommendations for the tiles.
How long does mat installation take compared to loose cable?
Installation of a heating mat in a bathroom of 4–5 m² takes an experienced tiler 2–4 hours (excluding the electrical part). A loose cable in the same space, including preparation, laying of fixing tapes and the cable itself, takes 4–8 hours plus time for pouring the mortar (half a day) and drying (4–6 weeks). Overall, the mat is several times faster during renovations.
Is the mat suitable as a primary heat source or only as supplementary heating?
It depends on the specific conditions. In a well-insulated bathroom with a power of 150 W/m² and an area of 3–4 m² (power 450–600 W), the mat can serve as a primary heat source even at outside temperatures below zero. In less insulated spaces or large rooms, it is advisable to supplement it with another source (radiator, infrared heater). The calculation of the required power always depends on the room's heat loss – not just on the area. More details can be found in the article What power of a heating mat do I need per square meter for a bathroom or living room?.
Conclusion: how to decide without doubts
If we had to simplify it into one rule: use a mat for renovations and small to medium areas under the floor; use a loose cable for new buildings with a conventional floor structure and larger areas requiring customized power. In practice, this means that 80–90% of standard customer orders in apartments and houses (renovation of a bathroom, kitchen, hallway) are ideally solved with a mat – it is faster, more convenient to install and does not require mortar. A loose cable is the right choice where you already have mortar, you need variable power or an irregular shape with a larger area.
The key step before any purchase is to accurately measure the actual heated area (not the total area of the room), decide whether it is primary or supplementary heating, and check the floor height. If you are unsure, consult a specialist – a properly chosen system will provide comfort for the next ten years.
Do you have a question about this topic?
Having trouble deciding or dealing with a specific situation in your home? Write to us – we will be happy to help.