Retrofitting the Thermal Comfort of Thin Underfloor Heating in Old Buildings

Leverage the benefits of a thin-layer system for modernisation projects

Thin-layer underfloor heating makes it much easier to retrofit the thermal comfort of underfloor heating in old buildings. The flat structure, with a minimum height of 17 mm, allows the thin layer system to be laid directly on the wooden floorboards in old buildings. The thin underfloor heating thus roughly compensates for the height of door thresholds, which are present in many old buildings and prevent barrier-free access to rooms.

Additional thermal insulation is only required in rare cases. An insulating layer underneath the underfloor heating may only be advisable for floors that are located directly above the ground, cellar rooms or above a doorway. Otherwise, the position of the heating pipes close to the surface ensures direct heat transfer to the room and rapid heating behaviour.

The use of RTL technology [return temperature limiter] allows the underfloor heating to be retrofitted room by room and also to be connected to conventional heating systems with high flow temperatures and controlled individually. The old radiators are thus replaced by the radiant heating. However, mixed operation is also possible, e.g. for an installation with a towel radiator in the bathroom. The existing heating source can continue to be used [for the time being].

Thermal comfort and standardised installation methods have made conventional underfloor heating the standard in new-build homes. In existing and older buildings, however, modernisation of the heating system is often postponed. Many owners are reluctant to fully renew the heating system due to the expected investment costs and a lack of thermal insulation.

It is precisely in these cases that the FLEXIRO thin-layer system offers the possibility of retrofitting the thermal comfort of underfloor heating in old buildings without turning it into a major project. If ceiling installation is an option, we also offer heated-chilled ceilings that work on the same principle.

To find out whether clip-on rails, studded panels or dry screed panels are the best installation option for your project, see our underfloor heating overview. Below we have summarised other specific advantages of the low profile system for retrofitting in older buildings compared to conventional underfloor heating.

Benefit Warmth and comfort

Thin-layer underfloor heating radiates heat extremely evenly over a large area through a tight loop of flexible 10 mm PE-RT pipe. As a result, the low flow temperature of the thin system is sufficient to provide surprisingly comfortable temperatures. The high level of radiant heat, which is also reflected from the walls and ceiling, means that even at a room temperature of just 20°C, low profile underfloor heating provides a temperature feeling that can only be achieved with convection radiators at 22°C.

This also reduces the required flow temperatures compared to conventional underfloor heating systems. The efficient use of energy saves heating costs while maintaining a high level of thermal comfort. The following diagram shows the temperature distribution of different types of heating based on the climatic zones of the human body. No conventional heating system comes as close to ideal temperature distribution as underfloor heating. The result is an even temperature pattern that provides a pleasant feeling of warmth.

Walking barefoot across the well-tempered floor in the bathroom is a real treat. Your family will thank you for it.

Benefit Health

With heating temperatures just above the surrounding environment, there is hardly any air turbulence. This minimises the circulation of allergens in the air. No wonder house dust allergy sufferers choose underfloor heating wherever possible. It also actively prevents the growth of mould and mildew, because the uniformity of the underfloor heating prevents cold bridges at corners and window reveals, and temperature differences in the room. Low-profile underfloor heating also creates a comfortable, homogeneous and healthy indoor climate in older buildings.

Benefit Design freedom

Another advantage of retrofitting underfloor heating in an old building is the design freedom it gives. Bulky radiators under windows, which limit the design and furnishing options, can be removed. Underfloor heating systems control the room temperature unobtrusively and evenly. The result is plenty of floor space and even more options for customising the rooms. There are also no limits to the choice of flooring: Natural stone, parquet, laminate, tiles or carpet - many materials can be used. The only thing is that the floor covering should not be too thick.

Benefit Weight

The extra weight can be a limiting factor when retrofitting underfloor heating. The load-bearing capacity of intermediate floors is sometimes limited, especially in older buildings. A low profile underfloor heating system has less material weight and, above all, less additional weight due to the thinly applied levelling compound. This reduces the load on the floor structure. Depending on the system, the material weighs between 1.9 and 2.2 kg/m². Heating water is already included. With a layer thickness of 17 mm, the levelling compound accounts for the largest proportion of the weight at around 25 kg/m². With conventional underfloor heating an additional load of 50 kg/m² or more can be expected.

Benefit Economic efficiency

Thin-layer underfloor heating is not only modern and healthy, it is also particularly economical. Narrow loops and installation close to the surface allow flow temperatures to be further reduced without compromising thermal comfort. Although there is generally no need for additional insulation, the system can make a significant contribution to reducing heating costs in older buildings. The low flow temperatures are particularly advantageous when modern heat generators are added at a later date. The low profile version is particularly efficient when operated with renewable energy sources such as photovoltaics or geothermal energy in combination with a heat pump.