Many homeowners think underfloor heating is only for new builds, but that’s not the case. Modern systems make it possible to install underfloor heating in existing properties without major disruption.

This guide explains how retrofitting underfloor heating works, which systems are most suitable, and what to consider before starting your project.

Can Underfloor Heating Be Retrofitted?

Yes, underfloor heating can be retrofitted in most existing homes. The key is choosing a system designed for low-profile installation. These systems require minimal floor build-up, meaning you don’t have to raise floors significantly or remove existing subfloors.

Electric systems and specially designed low-profile water systems are the most common solutions for retrofit projects.

Low-Profile Water Systems

A low-profile water system uses very thin heating pipes embedded in pre-routed panels or boards. The panels are laid directly over the existing floor or subfloor, adding as little as 15–20mm to the overall height.

Warm water flows through the pipes at a low temperature, providing even, comfortable heat across the room. These systems connect to your existing boiler or heat pump and work particularly well in larger areas such as living rooms or open-plan spaces.

Electric Underfloor Heating for Retrofits

Electric underfloor heating is often the simplest choice for retrofitting. It uses thin heating mats or loose cables installed directly under your flooring.

Because the mats are extremely thin, they add almost no height to the floor. They can be fitted under tiles, engineered wood, or vinyl, making them ideal for kitchens, bathrooms, and bedrooms. Installation is fast and causes minimal disruption.

Minimising Floor Height Increase

Floor height is one of the main concerns when adding underfloor heating to an existing property. To minimise the effect:
    •    Choose low-profile systems (water panels or electric mats).
    •    Use high-conductivity floor finishes such as tiles or engineered wood.
    •    Remove the existing floor covering before installation where possible.
    •    Use self-levelling compounds to create a smooth, even surface.

These steps help keep height gain to a minimum while maintaining excellent heating performance.

Insulation and Energy Efficiency

Good insulation is essential for retrofit installations. Insulation boards placed beneath the heating layer prevent heat loss into the subfloor, helping the system run efficiently.

Properly insulated retrofits can be as energy-efficient as new-build systems. They warm up quickly, retain heat for longer, and provide lower running costs compared to radiators.

Installation Considerations

Before retrofitting, it’s important to assess your current floor construction and heating system. Concrete and suspended timber floors may require different installation methods.

Professional installers will check the floor build-up, ceiling heights, and insulation levels to determine the best solution. They’ll also ensure your existing boiler or heat source can handle the additional demand.

Cost and Timescale

The cost of retrofitting underfloor heating varies depending on the size of the space, the type of system, and the floor construction.

Electric systems are usually cheaper to install but may cost more to run in large areas. Water systems have a higher upfront cost but deliver better long-term efficiency. Most retrofits can be completed within a few days, depending on preparation and drying times.

Frequently Asked Questions

Can I install underfloor heating on top of my existing floor?
Yes, with low-profile systems. The panels or mats can often be laid directly over existing floors with minimal height increase.

Do I need to replace my boiler?
Not usually. Most modern boilers are compatible, but it’s best to have an installer check your system before installation.

Can I use underfloor heating upstairs?
Yes. Lightweight systems can be installed between joists or over existing subfloors without adding significant weight.

Retrofitting underfloor heating in an existing home is easier and more practical than ever. With modern low-profile water and electric systems, you can enjoy the comfort and efficiency of radiant heat without major renovations.

Whether you’re updating a single room or the entire house, professional design and installation are key to achieving the best results.

For expert retrofit advice or a free consultation, contact the team at The Underfloor Heating Company.

We can help you find the ideal system for your home.