Standard UNI EN 1264

UNI EN 1264-4

UNI EN 1264-4:2009 is the part that offers help on the installation of radiant surface systems. It details the minimum material requirements to be used with a radiant surface system and the requirements that have to be met for successful installation.

It is the part of the standard that regulates the installation of surface-embedded radiant systems. The introduction to the standard sets out the contents of UNI EN 1264-4 and states that UNI EN 1264-4 applies only to the components that make up the radiant heating/cooling systems; it is not applicable to the other elements that make up the structure of floors, ceilings and walls. This means that, whatever the procedures and choices made before the radiant surface is laid, that established in UNI EN 1264-4 must be complied with, without exception, when installing the radiant system.

The standard describes the installation of the radiant surface, distinguishing between radiant floors, walls and ceilings. It defines the conditions that must be present at the time of laying the radiant floor system: the completion of the support base and closure of open parts of the building (e.g. windows and doors).

All the service tubing to the systems (hydraulic, electrical, sanitary, etc.) must have already been installed and covered in order to create a base on which to lay the insulation.
The insulation of the radiant floor system must have a minimum thermal resistance Rλ,ins greater than or equal to that specified in Table 1 of Paragraph § It must be covered on top by a protective layer which can be a polyethylene sheet of thickness equal to at least 0.15 mm or equivalent material.

The radiant floor must be laid leaving a perimeter strip along all the walls that delimit the area to be heated. Perimeter strips must also be left around all the structural components of the building that penetrate the screed (e.g. pillars, steps, etc.). The perimeter strip must penetrate down to the very bottom of the support and continue up to the finished floor level, allowing for at least 5 mm of screed movement. The perimeter strip and protective insulation layer must be positioned in such a way that the screed does not seep along the perimeter under the insulation.

The distribution manifold must be positioned in such a way as to minimise the length of supply tubing required. This is to avoid excessive supply tubing making it difficult to manage the temperature of the different rooms. It must have two on/off valves and a calibration unit for each circuit. Circuit closure and circuit calibration must be independent.

There must be mechanical devices to ensure that no water enters the system at a temperature that could cause very high temperatures to be reached in winter (55°C for traditional screed or as specified by the screed supplier). These devices must also work in the absence of an electric current. It must be equipped with humidity sensors if operated in cooling mode to prevent reaching dew point temperature.

The tubing used for the radiant floor circuits must have an oxygen barrier and meet the technical specifications of reference standards. Reference standards for PE-X, PP, PB, PVC-C, multi-layer, PE-RT, PE-MDX are cited in § UNI EN 1264-4 . The thickness of the tubing must be such as to meet Class 4 requirements according to ISO 10508, resistant to a working pressure of 4 bar and expected lifetime of 50 years. During transport and storage on site, tubing must be protected from external damage and direct sunlight. Tubing must be laid at least 50 mm from the perimeter and 200 mm from any possible cause of damage to the tubing e.g. flues, fireplaces with low hearths, balcony edges with embedded railings, etc.). The radius of curvature must comply with the manufacturer‘s instructions. Tubing must be attached using a secure anchoring system that ensures the tubing does not move more than 5 mm vertically and more than 10 mm horizontally from the position where it was installed. The two lengths of tubing of each circuit that cross the expansion joint (both the feed and return tubes may cross only once) must be protected with flexible insulation material for a length of at least 0.3 m.

Before laying the screed onto the coils, a pressure of no less than 4 bar and no greater than 6 bar must be applied to make sure there are no leaks. This test can be performed using water or compressed air. The absence of leaks must be documented in a test report which must also include details of the pressure at which the test was performed.

In relation to the screed, UNI EN 1264-4 recommends that its thickness is no less than that stipulated by the regulations specifying screed load capacity and bending strength class. The screed must be laid respecting the expansion joints where necessary. Joints must be positioned - and be of sufficient number - to delimit areas not exceeding 40 m2 and no longer than 8 m. These dimensions may be exceeded in the case of rectangular areas if one dimension is no more than double the other. There must be no areas of irregular shape. Joints must be positioned by all the doors. If superficial cuts are made to the screed, these must not have a depth greater than a third of the thickness of the screed. Extreme care must be taken when laying the screed so as not to damage any of the components of the radiant floor. The laying of the screed and subsequent drying for least 3 days must take place at a temperature not less than 5°C. For at least 3 days the screed must be protected from drying too quickly. Such protection may be necessary for a longer period if the type of material used for the screed so requires it. The flooring contractor must check that the chosen floor finish is compatible with the conditions.

With regard to radiant ceiling and wall systems, the regulations refer to the prescriptions already described for radiant floor systems, with the following additions and/or modifications: Walls and ceilings must be able to support the radiant system. The layer of insulation necessary to achieve the minimum thermal resistances shown in Table 1 of Paragraph § may be divided into two separate layers, depending on adjacent room conditions. For example, in the case of an external wall, one layer will be installed directly behind the radiant system and a second layer will be installed externally. The supply temperature of the radiant and/or ceiling system must not exceed a maximum value which is dependent on the material into which the tubing is embedded. For example, in the case of plaster, the flow temperature must not exceed 50°C.