The screed for a heated floor incorporating the heating elements (water pipes in hydronic systems or heating cables and pre-formed cable mats in electrical systems) has a very important role in the efficiency of the system and it must therefore have very good thermal conductivity to enable efficient heat transfer to the spaces above and to improve the warm up time of the system.
Furthermore, in hydronic underfloor heating systems, very high conductivity screeds enable the fluid to be circulated at lower temperatures whilst providing the same level of comfort. It also enables the heat to be generated more efficiently (in condensing gas boilers or by geothermal, solar, or heat pump systems etc.) and reduces energy consumption.
Reducing the application depth of underfloor heating screeds is also important because it lowers the thermal mass of the system, allowing a faster response with improved efficiency and comfort, and because it allows intervention on sites where, for construction reasons, the available depth is very low, especially in renovation and refurbishment.
The PaRis range of screeds, developed specifically for underfloor heating and cooling systems, provides an optimum response to these requirements.
High thermal conductivity semi-dry screed with metallic fibres: Paris 2.0
Massettomix Paris 2.0 premixed bagged screed is specifically designed for heated floors. Thanks to its specific mix design including rustproof metallic fibres It has high conductivity (lambda = 2.02 W/mK) and can cover an area of up to 150 m2 without joints or mesh reinforcement. It high compressive strength, and does not require the use of any underfloor heating screed admixture. The heating system can be turned on for preconditioning only 7 days after the screed has been laid.
Paris 2.0 has a semi-dry consistency and its application is simple and traditional.
Flowing screed for low depth application: Paris SLIM
Underfloor heating screed made with PaRis SLIM self-levelling mortar has the peculiarity of allowing very reduced application depth, varying depending on the type of the heating system characteristics:
- 10 mm over the heating pipes (or pipe locating castles) in traditional systems with insulation board.
- 5 mm or 7 mm over the heating pipes (or pipe locating castles) in new generation “slim” systems with thin base panels.
PaRis Slim has a controlled shrinkage and also allows the construction of large surfaces (up to 200m²), without shrinkage control joints and/or without the use of reinforcing mesh and allows the heating system to be commissioned after only four days.
Bagged premixed, its application is similar to that of common self-levelling mortars with a continuous mixing and pumping machine or after mixing in a bucket with an electric mixer.
The supporting layer for underfloor heating can incorporate service runs such as pipework for other electrical or water services and prepares the surface for the application of the pipe support boards or heating cables. It can make a significant contribution to reducing downwards heat loss. This is particularly important if the spaces below are unheated.
Latermix Cem Mini Insulating concrete based on expanded clay is 10 times more insulating than a traditional or self-levelling mortar and provides effective support for insulating boards when used as a substrate for underfloor heating sytems. It complements (or in some cases replaces) the system’s own insulation (insulation boards). In addition to being insulating, it is ultra-lightweight (only 600 kg/m3) and significantly reduces the dead loads on the supporting slab: a very useful feature, especially in refurbishment.
The use of Laterlite Plus Hydrophobic Expanded Clay as insulating layer for heating systems that are in contact with the ground prevents rising damp and heat loss into the ground. It is recommended as the base layer for heated industrial floors because of the excellent mechanical strength and stability of expanded clay, which make it compatible with heavily loaded floors (factories, warehouses and shopping centres). For further information, please refer to the section on insulation in contact with the ground.