General Information

Suspended floors require the space between the joists to be filled with insulation once the underfloor heating has been installed. This prevents downward heat loss either into an externally ventilated void or to the room below.

You fix a heat transfer clip onto the top edge of the joist, providing a cradle for the underfloor heating pipe work to fit into. At this stage, the clip is separate from the aluminium conducting plate which can be positioned freely to match your underfloor heating layout. When the pipe work has been installed and the insulation fitted, and you are ready for the floor deck to go down, the aluminium conducting plates need to be laid across the top of the joists. These aluminium sheets connect all the heat transfer clips, drawing the heat away from the pipe work, dispersing it across the floor to provide an even floor temperature.

Once the pipe work is installed to our specification, then the system should be filled with water and pressure tested.

Insulation

The insulation thickness can vary depending on the project. Building regulations will require a specific amount of insulation to be used. This will usually be more than the underfloor heating requires and therefore not be a problem. Suspended floors require the insulation to be fitted between the joists, and should be tight up against the underside of the floor deck and underfloor heating.

Build Up Heights

Suspended floors are very convenient, in that they do not significantly raise the floor level. The height is set by the top of the joists that the underfloor heating is fitting to. This is especially useful when the project has existing joists and limited build up heights. The thickness of the pipe clip is 0.6mm and the aluminium conducting sheet is 0.5mm thick. This means that there is no significant rise in floor heights from that originally planned for when joists were specified.

Temperatures and outputs

Suspended floors have a limited output compared to the screed systems, although this output should be more than enough heat for modern well insulated buildings. Whilst these outputs are lower, the water temperature required to run them is higher, normally around 55 – 60c. These specifications will allow the system to produce 70w/m2 with a maximum surface temperature of 27c.

In a modern building with high levels of insulation and modern high specification double glazing, the floor temperatures are normally  within a few degrees of the air temperature in the room, providing a warm and comfortable enviroment even in very cold weather.

If you have a poorly insulated building, you should always refer to the heat loss calculations that are prepared at the quotation stage to ensure that these issues are highlighted as early on in the project as possible.