floors are made with screed that is a smooth sand and cement mix,
which is laid over an insulation base. Screed floors can be built
up from solid foundations or in the case of beam and block floors,
on intermediate floors.The pipe is laid at 200-300mm centres dependent
upon design. Care must be taken to protect the pipework whilst
installing the screed.
Finally the floor finish is laid. Underfloor heating works well
with almost any floor finish; tiles, carpets (use carpets with
a resistance of less than 0.15 m2K/W), timber floors, plastic
The floor coverings and the adhesive must be suitable for the
temperatures that underfloor heating will provide, the maximum
temperature they need to resist is 40°C. Always check with
the manufacturer of the floor covering if it can be used for underfloor
heating. Timber floors need to have a moisture content below 10%
to avoid shrinkage. The system must be operated for 21 days with
a very low temperature to dry the screed, then the floor covering
can be laid.
SCREEDED FLOORS can be undertaken a number of ways depending on
the situation. If there is already
insulation in the main concrete slab, we recommend that an additional
22mm be laid to act as a barrier, this is to stop the pipework
heating anything else apart from the final
screed on top. 75mm of screed is required.
laid screed is normally mixed on site or pre-mixed and delivered
by a supplier. Hand laid screeds is the more common method for
The performance of each system is dependent of many factors, these
being flow temperatures from the boiler, Air-change rates, U-values
of the property and of course,
which system you have had installed. This can be averaged out
as follows, 95-105 watts per M² for screeded systems, 70-80
watts per M² for plated and 65-75 watts per M² for
Self-levelling liquid screeds are delivered and installed by specialists.
The screed is ‘pumped’
in liquid form and is quick drying. This method of screeding is
more common for multiple/commercial projects.