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Installing Underfloor Heating in an Existing House

When it comes to underfloor heating systems, a frequently asked question is whether it is possible to retrofit a new system in an existing home. In this guide we’ll look at:

  • The difference between ‘retrofitting’ and ‘refitting’ a system
  • If UFH will raise floor levels
  • The ease of installing floor heaters in old houses
  • Common problems if refitting a system
  • The best heating controls to use
  • Why underfloor insulation is recommended


If you’re planning your upcoming home renovation project, underfloor heating is perfect for bringing radiant warmth to existing houses – a process known as retrofitting. The terms ‘refit’ and ‘retrofit’ are easily confused; when it comes to floor heating systems, ‘refit’ means removing the current heater and moving it somewhere else, ‘retrofitting’ means installing a new heater into an existing house, as opposed to a new-build home. In most cases people mean retrofitting when exploring a floor heating solution for their home and many of Warmup’s underfloor heating systems can be fitted both into new-build and existing properties with the original subfloors.

Electric underfloor heating is well-suited to retrofit projects, with most of Warmup electric system’s having little-to-no impact on floor heights – a key concern for home renovation projects where ceiling heights and door levels are fixed. The StickyMat System for instance, uses an ultra-thin heating wire and can be installed directly within the layer of tile adhesive when installing with tiled flooring. Find out more about the impact of UFH on floor levels.

As mentioned earlier electric underfloor heating can be fitted in both new and old properties, and on existing subfloors. However the actual floor finish such as tile, laminate or vinyl needs to be removed and replaced with a new floor finish. In other words, fitting underfloor heating onto existing floors means removing the existing floor covering, adding insulation boards (if necessary), installing the heater on them and then laying down a new floor covering above the heating system. It is very difficult to lift up the existing floor finish and lay the same floor back again after the installation of an underfloor heating system. It goes without saying that most of the floor finishes such as tiles are doomed to get damaged when lifting the floor up. Electric underfloor heating is therefore a perfect option for people who are wishing to change their floors whilst renovating, because the heater is very thin and does not raise the floor height visibly.

The installation of the electric underfloor heating system is also quick, easy and clean. However it is important to involve a qualified Part P certified electrician in the project to ensure that the electrical distribution is designed and carried out correctly.

Retrofitting of other heating systems usually means more laborious work including removal of old floors (not just the floor finish but the whole floor), refitting of new ones and finally, installation of pipework and boilers. This again increases the overall cost of the renovation.

Underfloor heating


As discussed earlier many people confuse the terms ‘refit’ and ‘retrofit’. For those ones who nevertheless are looking to actually refit the system, we must say that an electric underfloor heating system should only be fitted once. It is not possible to take up an existing system and refit it into a different room. This is due to a number of issues:

The wires can be damaged when removing the floor finish, specifically tiles or stone:

  • The wires can be damaged when removing them from the adhesive, especially if they are pulled, stretched or bent.

  • If the wire is on a mesh, it may prove impossible to remove the system without damaging it, as the mesh should be fully embedded in the adhesive.

  • A heater can only be used in the room size it is designed for, therefore refitting an existing installed heater into another room would not work.

It is also good to bear in mind that to refit a heating systems would void any guarantee or warranty.

If you have any queries about refitting your heating system and the implications on your warranty, get in touch with our team who will be happy to help.


The ease of fitting an electric underfloor heating systems has allowed millions of homeowners to install a warm, comfortable and highly controllable heating in individual rooms or as a whole house heating systems.

Underfloor heating can be controlled with any thermostat. The increase in technology in thermostatic control systems has allowed the heating systems to work automatically without you needing to manually control them. The Warmup 4iE Smart WiFi Thermostat learns your habits, knows when you are in and can even predict when you are coming back home, adjusting the temperature accordingly. With the MyHeating app to go with the thermostat you can control the heating in your home from a remote location. A smart thermostat does not only increase the overall comfort, but decreases energy usage, as your heating is on for less time and only when you need it, leading to cost savings.

In many cases the floor can be powered using existing ring mains with a fused spur powering the thermostat. All heating systems should always be powered by a circuit protected by a Residual Current Device (RCD). If any of these terms sound unfamiliar It is recommended to consult with a qualified Part P certified electrician in regards with RCD.

Underfloor heating - warmup


There is a wide range of floor heating systems available for many different floor coverings, including carpet, wood, stone, laminate and vinyl, as well as subfloor types including concrete floors and timber joisted floors. It is advisable to ensure adequate subfloor insulation when considering retrofitting an underfloor heating system.

We offer a collection of floor insulation products that will greatly enhance the energy-efficiency of your new heating system. Our hydronic heating solutions use system-specific insulation that come as part of your chosen heating system – get an instant hydronic quote today to see how much you could expect to pay to install water underfloor heating in your existing home.

Most of our electric systems can be installed alongside our Insulation Boards, which feature great thermal conductive properties.

If concerned about the floor heights, the Warmup insulation board for concrete floors is only 10mm thick and for wooden floors 6mm thick. Although insulation is not a prerequisite, it is recommended to ensure heat is directed upwards and not into the subfloor. Good insulation decreases the heat up time and ensures the system is as efficient as possible.

When tiling or laying stone floors, it is always important to ensure the floor is sturdy and free from flexing, regardless of installation of an underfloor heating system. If in doubt, the floor might require additional strengthening of a quality plywood or other appropriate material.

Finally, electric underfloor heating does not require any maintenance unlike conventional heating systems ran by boilers. Therefore it is a secure and cost-efficient heating system that lasts for a lifetime whilst keeping your toes warm and cosy. Call the Warmup Technical helpline on 0345 345 2288 for further advice or send a quick quote to inquire prices for your project.


Underfloor Heating

Underfloor Heating from the Worlds Best selling Brand, Warmup, starts from less than £200 and costs less than £20 per year to heat a typical bathroom floor – all with a lifetime warranty”.


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