Underfloor Heating And Retrofitting: A Complete Guide


Wet underfloor systems are an increasingly popular method of primary heating and a great alternative to radiators. It makes the most sense to incorporate the underfloor heating at the new-build stage – it is quicker and cheaper to install at this stage, as well as offering the best heat output.

However, for a variety of reasons, many homes are built without underfloor heating – this could be due to cost, specification or even awareness of the benefits over traditional radiator systems. Many UFH systems are considered once a home is already built.

Traditionally underfloor heating has only been installed at the new-build stage, but with the introduction of a range of retrofit solutions, it is now possible to install UFH into existing houses.


What is retrofitting?

Retrofitting is the term used when a product, component or system is added after the initial manufacture stage. Retrofitting UFH is the process of adding underfloor heating to a building or space after the manufacture/build has already taken place.


How to ‘Retro-fit’ UnderFloor Heating

One of the main challenges when adding UFH to an existing house is the impact that it has on the floor-to-ceiling height. Any UFH system has to incorporate the pipework, as well as a reliable and sturdy layer to uphold the integrity of the floor surface.

Low-profile UFH systems are designed to minimise the impact on the floor build-up. While low-profile systems are typically slightly lower heat output than systems installed at the new-build stage, they are still often acceptable as a primary heat source. Typically, these systems consist of a network of pipes laid within a thin, grooved panel. This can then have floor finishes laid directly over, sometimes with the addition of an additional board layer, or levelling latex, and finally can then be covered by a choice of flooring.




What are the benefits of retrofitting underfloor heating?

Many homeowners and businesses see the benefits of UFH after the initial build has been completed. UFH is a long-term return on investment solution for heating your project that maximises floor space and increases the value of your home

Traditionally, retro-fitting UFH to a project has involved very intrusive works – i.e. digging up the existing floors, prior to laying the pipework and re-screeding.  Being able to use low-profile systems that can be retrofitted is a completely different approach, with minimal disruption to the floor.

Retrofitting underfloor heating can be a clean and low-hassle way of adding UFH to your home.




How much does it cost to ‘retro-fit’ underfloor heating?

There is some negative press around the cost of retro-fit underfloor heating, which needs some clarifying. While it is true that a typical retrofit UFH system costs more per m2 than a new-build system, it doesn’t take into account that there is no screeding process involved in retrofit solutions. This cuts out considerable costs and time for the screed to dry.

Many people are deterred by the up-front cost of UFH, but it is always good to look at the long-term investment.  With savings off your energy bills over time, the investment can quickly start to pay off


Retrofitting underfloor heating: what to consider

Planning and preparation are key for retrofit UFH systems. This is because the pipework will mostly run within pre-grooved channels—the means of securing the pipe. This is different from a screeded system in a new-build project because the pipe layout is more flexible.

Panels need to be laid out in an intelligent and accessible manner to make sure the pipe network will reach all areas and be able to return to the manifold. Pipework can sometimes be run through walls to avoid cluttered transit areas around the manifold.

Careful planning is essential, coupled with a smart and comprehensive design to help ensure your installation goes to plan and achieves what it should

Recommendations of relevant manufactures must also be considered in relation to floor finishes. Almost always, chipboard or plyboard would be laid on top of a grooved polystyrene type system to provide a solid base for the subfloor. The solid engineered wooden floor is an exception to this and can be laid straight down on top of a polystyrene type UFH system.

When using a cement board or chipboard type system, typically you can lay final floor finishes like tiles and wood floor immediately on top of the UFH system. This minimises further costs and floor build-up.


Underfloor Heating


Best underfloor heating systems for retrofitting

The development of low-profile UFH systems has made retrofitting UFH even simpler.


ambilowboard EPS


AmbiLowboard EPS system

This system is ideal for builds where floor height is at a premium. It can be used in a suspended floor application if there is a level and firm structural flooring layer over the joists. This will enable the AmbiFloat panels to fully support the floor finishes.

The 18mm insulation of this system is pre-grooved to take the 12mm UFH pipework and covered with foil to maximise heat distribution (up to 80w/M2). This system has a quicker response time than a traditional screed UFH system.

The installation of the AmbiLowboard EPS system requires covering the complete floor area with insulations panels and using battens to provide extra support to threshold and perimeters where necessary.


SRB ambilowboard


AmbiLowboard SRB system

This system is a grooved cement board UFH that is ideal for retrofit application. It is designed for hard floor finishes such as tiles and wood flooring—they can be laid directly on top of the installed system. The board are provided in two pre-routered panels—straight boards and return panels but this depends on the pipework pattern design.

The cement material of the board gives it a low thermal resistance which ensures even heat spread. It is essential that this system is laid on a flat, level and solid base.

Carpets and vinyl can’t be laid directly onto the AmbiLowboard SRB system but can be laid if the system is topped with an additional layer such as 6mm plywood.





The AmbiSolo system is made of a 12mm UFH pipe with a plastic castellated panel. This is all covered with 20mm of reinforced levelling compound.

This system must be laid directly onto a structural and level sub-floor. No loose flooring or insulations layers can be involved as a 20mm compound is not structural in its own right.

This retrofit UFH system has unique benefits. It has a very quick response time (15-30 minutes dependent on the floor covering) and the output can be up to 120W/M2.

Most floor finishes can be laid directly on top of the AmbiSolo system. Tiled floors are recommended with the use of a decoupling membrane to soak up any lateral  movement that can cause cracks in the grout joints over time


AmbiDeck 18


AmbiDeck 18

Our latest addition, The AmbiDeck 18 system really does give the best of both worlds – it provides a low-profile underfloor heating system, which incorporates an insulation layer and can be tiled directly onto.AmbiDeck 18 consists of a high-density XPS insulation panel, 18mm thick. The face of the panel is cement-coated, making it rigid and durable.

It is grooved to take 12mm UFH pipework, with a radius return grooved into each panel, making the panel universal. Additional pipework channels can easily be routed/grooved into the panel. AmbiDeck 18 must be laid onto a flat and level subfloor, which can either be concrete or timber-based. Over a concrete floor, we recommend laying the AmbiDeck 18 panels over a combed layer of flexible tiling adhesive.

Over a timber floor, we recommend securing the panels down with screws, using the AmbiDeck washers. Tiles and wood flooring can be laid directly over this system. Other finishes such as carpets or vinyl will require an intermediate board layer, prior to the finish being installed.


At Ambiente, we give quality and realistic advice, to make sure that you can incorporate Underfloor Heating into your home.  We have solutions for every scenario and we have supplied our systems into many different buildings across multiple sectors.

Misconceptions about the issues surrounding retrofit UFH can become a thing of the past with guidance from Ambiente and our in-depth installation guides.

Consider a refit UFH project? Contact Ambiente today on 01707 649 118 or info@ambienteufh.co.uk