Electric Underfloor Heating FAQs

Underfloor heating uses the floor surface to distribute heat throughout a room.

With electric underfloor heating, heating cables, mats or heating elements are installed beneath the finished floor.

As the system warms the floor, heat is transferred upwards into the room.

This creates a large, gently heated surface rather than concentrating heat in individual radiators.

Electric underfloor heating passes electricity through a specially designed heating cable or element.

This produces heat beneath the floor covering.

The floor then becomes a large radiant heating surface.

A thermostat controls the system and switches the heating on and off to maintain the required temperature.

• Comfortable, even warmth
• No wall-mounted radiators
• Individual room control
• Simple installation
• Very little maintenance
• Quiet operation
• Suitable options for many floor finishes
• Programmable and WiFi control options

Running costs depend on the system, heated area, insulation, room temperature, electricity tariff and operating time.

The basic calculation is:

System power in kW × electricity price per kWh × operating time

However, the heating does not normally operate at full power continuously.

A thermostat switches the system on and off as required once the floor and room reach the selected temperature.

Good insulation and effective controls can make a significant difference to energy use.

First, calculate the total wattage of the heated area.

For example, 5m² of 150W/m² heating gives a maximum connected load of:

5 × 150W = 750W

This is equal to 0.75kW.

You can then calculate the maximum hourly cost using:

0.75kW × your electricity price per kWh

Remember that this represents continuous full-power operation.

A thermostat will normally cycle the heating on and off once the required temperature has been reached.

No.

A correctly controlled electric underfloor heating system does not need to remain fully energised all day.

The thermostat monitors the temperature and switches the heating on and off as required.

Programmable controls can also reduce the temperature or switch the heating off when the room is not required.

Warm-up time varies.

The main factors include:

• Floor construction
• Insulation below the heating
• Heating output
• Floor covering
• Starting temperature
• Required temperature

A well-insulated system positioned close to the finished floor will normally respond faster than a system installed above an uninsulated concrete floor.

Insulation helps direct more of the heat towards the room.

Without suitable insulation, some energy can travel downwards into the subfloor.

This can increase warm-up time and energy consumption.

For refurbishment projects, even relatively thin insulation boards can help improve system response.

They are not required in every floor construction, but they are often recommended.

Insulation boards can reduce downward heat loss and help the floor warm more quickly.

The correct insulation depends on the existing floor and the heating system being installed.

Yes, in a suitable building.

Electric underfloor heating can provide primary room heating when the available heated floor area and installed output are sufficient to meet the room’s heat loss.

In other applications, it may be used mainly to provide a warm floor and supplementary heating.

The heating requirement should be calculated before choosing the system.

In many rooms, yes.

If the system provides enough heating output to match the calculated heat loss, underfloor heating can be used without radiators.

However, rooms with high heat loss or very limited available floor area may require additional heating.

Correct system design is important.

Many people prefer the way underfloor heating distributes warmth.

The large heated floor surface provides heat across a wider area rather than from a small number of radiator locations.

It also means there are no hot radiators taking up wall space.

Many people prefer the way underfloor heating distributes warmth.

The large heated floor surface provides heat across a wider area rather than from a small number of radiator locations.

It also means there are no hot radiators taking up wall space.

The ideal setting depends on the room and floor covering.

The thermostat controls both comfort and floor temperature.

Some floor finishes have maximum permitted temperatures.

Always follow the flooring manufacturer’s instructions when setting the maximum floor temperature.

Yes.

Electric underfloor heating should be used with a suitable thermostat.

Depending on the system, the thermostat can monitor room temperature, floor temperature or both.

Programmable controls can also set different temperatures for different times of day.

Yes.

Flexel offers WiFi control options for suitable underfloor heating systems.

These allow heating schedules and temperature settings to be managed using compatible smart devices.

This can be useful for changing schedules or adjusting heating remotely.

Yes.

Separate rooms or heating zones can have independent controls.

For example, the bathroom can operate on a different schedule from the kitchen or living room.

Zoning helps you avoid heating rooms when they are not required.

There is no single system that is best for every floor.

The correct product depends largely on the floor covering and room layout.

Flexel offers several different electric underfloor heating options, including:

• EcoFloor heating mats for tiled and similar hard floors
• EcoFlex loose heating cables for irregular layouts
• EcoFilm heating film for suitable laminate and engineered wood floors

Choosing the correct product before installation is essential.

An underfloor heating mat uses heating cable attached to a mesh backing.

The mesh keeps the cable at a consistent spacing and allows the mat to be rolled across the floor.

This makes heating mats particularly convenient for regular-shaped rooms.

Flexel EcoFloor heating mats are designed for electric underfloor heating installations beneath suitable hard floor finishes.

EcoFloor is Flexel’s electric underfloor heating mat system.

The heating cable is fixed to a flexible mesh, making it quick to position across the floor.

EcoFloor is particularly suited to tiled floors in areas such as:

• Bathrooms
• Kitchens
• Utility rooms
• Hallways
• Extensions
• Living areas

The correct system output should be selected for the particular application.

EcoFlex uses a flexible loose heating cable rather than a pre-spaced mat.

The installer positions the cable across the available heated area.

This makes EcoFlex particularly useful for irregular rooms or areas with obstacles.

It can help maximise heated floor coverage around fixtures and unusual room shapes.

Heating mats are often the easiest choice for regular-shaped rooms.

Loose cable can be more suitable when the floor contains:

• Curved areas
• Narrow sections
• Fixed bathroom fittings
• Kitchen units
• Obstacles
• Irregular room shapes

The objective is to achieve good coverage of the usable floor area.

EcoFilm is an ultra-thin electric heating film designed for suitable floating floors.

It is particularly suited to laminate and engineered wood flooring.

The heating film sits beneath the floor covering and provides even heat across a large surface area.

EcoFilm can be an attractive option where a low floor build-up is important.

Yes.

Tiles are one of the most popular floor coverings for electric underfloor heating.

Ceramic, porcelain and natural stone transfer heat effectively from the heating system into the room.

Flexel EcoFloor mats and EcoFlex cable systems can be used with suitable tiled floor constructions.

Yes, with the correct heating system and suitable laminate.

Flexel EcoFilm is designed specifically for use beneath many laminate and engineered wood floating floors.

Always confirm that the chosen flooring is approved by its manufacturer for use with electric underfloor heating.

Yes.

Suitable engineered wood flooring can be used with the correct electric underfloor heating system.

The flooring manufacturer should confirm its maximum permitted temperature and thermal resistance.

Flexel EcoFilm is designed for suitable floating engineered wood floors.

Some suitable wood flooring can be used with electric underfloor heating.

However, solid wood can be more sensitive to changes in temperature and moisture.

Always check the flooring manufacturer’s instructions before installation.

Engineered wood is often easier to combine with underfloor heating because of its more stable construction.

Some vinyl flooring is suitable for underfloor heating.

The system and floor construction must be compatible with the chosen vinyl.

The flooring manufacturer should also provide a maximum operating temperature.

Flexel can advise on the appropriate system and floor construction.

Yes, with the correct system and suitable carpet and underlay.

However, carpet acts as an insulating layer.

Thick carpet and underlay can restrict heat transfer from the floor into the room.

Always check the combined thermal resistance or tog rating before specifying the system.

Hard floor finishes generally transfer heat very effectively.

These can include:

• Ceramic tiles
• Porcelain tiles
• Natural stone
• Slate
• Suitable engineered flooring
• Suitable laminate
• Suitable vinyl

Other floor coverings can also work when the complete floor construction is designed correctly.

Care should be taken with thick rugs.

A heavy or highly insulating rug can restrict heat escaping from the floor.

This may lead to a warmer localised floor temperature beneath the rug.

Check the heating and flooring manufacturer’s guidance before using large or thick rugs over heated areas.

Electric underfloor heating is normally installed across the usable exposed floor area.

It should generally not be installed beneath permanently fixed kitchen units or other objects that prevent heat from escaping.

The installation plan should identify fixed furniture before the heating system is laid.

The heating layout should normally avoid permanently fixed sanitaryware.

The usable floor area should be calculated before ordering the heating system.

This also prevents purchasing more heating mat or cable than the room can accommodate.

Yes.

Bathrooms are one of the most popular applications for electric underfloor heating.

A warm tiled floor can provide additional comfort while removing the need for some wall-mounted heating.

Bathroom electrical installations must comply with current electrical regulations.

The correct Flexel product should also be selected for the floor construction.

Yes, when a suitable system and floor construction are used.

The waterproofing, heating and floor finish must be designed as a complete system.

The electrical installation must also meet the requirements for the location.

Seek professional advice before installing electric floor heating in wet areas.

Yes.

Electric underfloor heating works particularly well beneath tiled kitchen floors.

When measuring the heated area, exclude permanently fixed kitchen units and other areas where heating cannot be installed.

This gives a more accurate heated floor area.

Yes, but conservatories can have high heat loss.

Large glazed areas and external walls can increase the heating requirement significantly.

A heat-loss assessment is recommended before relying on electric underfloor heating as the only heat source.

Higher-output heating systems may be suitable for some applications.

Yes.

Electric underfloor heating is particularly suitable for refurbishment projects because several systems have a relatively low build height.

The best product depends on whether the existing floor is concrete, timber or another construction.

The final floor covering must also be considered.

It can increase the floor level, but the amount depends on the system and floor construction.

Some electric heating systems are extremely thin.

Insulation boards, levelling compounds and the chosen floor finish can have a greater effect on overall build height than the heating element itself.

Plan the complete floor construction before starting work.

Yes.

Electric underfloor heating can be installed over suitable concrete subfloors.

Adding appropriate thermal insulation above a cold concrete slab can improve warm-up time and reduce downward heat loss.

The surface must be properly prepared before installation.

Yes, with the correct floor construction.

The subfloor must be stable and suitable for the heating and final floor finish.

The installation method will depend on whether the finished floor will be tile, laminate, engineered wood or another material.

Yes.

Electric underfloor heating can be installed on upper floors where the floor construction is suitable.

It is often used in upstairs bathrooms and en suites.

The installation method should match the subfloor and final floor covering.

Measure the total floor area first.

Then subtract areas that will be permanently occupied by fixed furniture or sanitaryware.

Typical exclusions include:

• Kitchen cabinets
• Baths
• Shower trays where applicable
• Built-in cupboards
• Fixed floor-standing furniture

The remaining area is the available heated floor area.

Should I buy a heating mat the same size as the room?

Usually not.

The heating system should be sized according to the available heated floor area rather than the total room size.

For example, a 10m² bathroom may only have 6m² of usable floor once the bath, shower and furniture are excluded.

Always calculate the available heating area before ordering.

The mesh backing of a heating mat can usually be cut and turned to change direction during installation.

The heating cable itself must never be cut, shortened or damaged unless the particular product instructions specifically state otherwise.

Always follow the Flexel installation guide supplied with the product.

No.

Heating cables should not cross, overlap or touch each other unless the product instructions specifically permit it.

Correct cable spacing is important for safe and even heat distribution.

Stop the installation if damage is suspected.

Do not cover the heating system until the required electrical tests have been completed.

In many cases, specialist equipment can identify the position of a damaged cable.

A qualified electrician or specialist repair company should assess the system.

Yes.

Testing is an important part of the installation process.

The heating system should be electrically tested at the stages specified in the installation instructions.

This helps identify accidental damage before the system is permanently covered.

Some parts of the installation can be completed by a competent installer or experienced DIY user, depending on the product.

However, the electrical connection and required electrical testing must be completed in accordance with current UK electrical regulations.

Flexel recommends following the installation instructions carefully and using a qualified electrician for the electrical work.

Electric underfloor heating installations require appropriate electrical protection.

The exact circuit protection should be determined by the electrician responsible for the installation.

Always follow current wiring regulations and the Flexel installation instructions.

Electric underfloor heating requires very little routine maintenance.

Once installed beneath the floor, there are no pumps, valves or moving components within the heating element.

The thermostat is the main user-operated component.

Correct installation is therefore particularly important because the heating system will become part of the floor construction.

A high-quality electric underfloor heating system can provide many years of service when correctly installed and operated.

The heating cable or element has no moving parts.

The most important factors are correct installation, electrical testing and protecting the system from damage before the final floor covering is fitted.

Yes.

Electric underfloor heating uses mains electricity, so electricity generated by solar PV can contribute towards its energy consumption.

The amount supplied directly by solar depends on when the heating operates and how much electricity the solar system is producing.

Battery storage may also allow more solar-generated electricity to be used at different times.

Yes.

Suitable thermostat controls can provide programmable and WiFi functionality.

Depending on the control system, users can manage temperatures and schedules from compatible smart devices.

This provides more flexibility than a simple on/off control.

Yes.

Electric floor heating has no pumps or fans within the heating system.

It therefore operates silently.

This makes it suitable for bedrooms, home offices and other quiet spaces.

Underfloor heating does not require fans to distribute heat.

It provides heat across the floor surface rather than blowing warm air around the room.

Normal household ventilation and cleaning are still important for maintaining indoor air quality.

Electric underfloor heating is not the best solution for every project.

Things to consider include:

• Electricity running costs
• Available heated floor area
• Building heat loss
• Floor covering compatibility
• Floor build height
• Insulation levels
• Electrical capacity
• Installation beneath the finished floor

Electric UFH can be particularly attractive for individual rooms and refurbishment projects.

For large buildings requiring continuous heating, other heating technologies may also be worth considering.

Both systems have advantages.

Electric underfloor heating is generally simpler to install and can be ideal for:

• Bathrooms
• Kitchens
• Individual rooms
• Extensions
• Refurbishments

Water-based underfloor heating can be attractive for large new-build projects or whole-house systems.

The best option depends on installation cost, floor construction, room size and how often the heating will operate.

Yes.

Underfloor heating can be used alongside other heating systems.

For example, electric UFH may provide warm floors in bathrooms while another system heats the rest of the property.

It can also provide supplementary heating in rooms where additional comfort is required.

Start by measuring the available heated floor area.

Then consider:

• Room size
• Floor construction
• Insulation
• Heat loss
• Floor covering
• Required room temperature
• Available electrical supply

Do not choose the system simply from the total room floor area.

Flexel can help identify the most suitable product for your project.

The required output depends on the application.

For many internal tiled rooms, 150W/m² electric heating mats provide a practical solution.

Rooms with higher heat loss may require a different design.

Flexel EcoFilm standard heating film provides 130W/m² for suitable floating floors.

The correct output should always be chosen for the room and floor construction.

Flexel has been developing and manufacturing electric heating products for decades.

Our electric underfloor heating range provides solutions for a wide variety of floor coverings and room layouts.

The range includes:

• EcoFloor heating mats
• EcoFlex loose heating cables
• EcoFilm heating film
• Underfloor heating controls
• Insulation and installation accessories

Whether you are heating a bathroom, kitchen, extension or larger area, we can help you choose the correct system.