Composition and screed cover
Il screed must be sufficiently rigid to withstand without deformation of the static and dynamic loads it is subjected: for this purpose along with good compactness, it must have the correct thickness.
In residential construction, for plants floor heating with pipes embedded in the backing layer above the minimum nominal thickness of the tubes is 45 mm: for smaller thicknesses follow the regulations.
In the preparation of the dough use the appropriate flow improver to reduce the water content and as a final effect of the quantity of air in the layer: the thermal conductivity of the substrate is improved.
Follows the composition the screed coverage of the system floor heating for a minimum thickness of 45 mm above the pipe:
- Portland cement 325 50 Kg
- Graded sand ÷ 0 8 225 mm Kg
- Clean water 18 lt
- Lt additive 0,5
And 'advisable that the'addition of the additive has postponed compared to the other components of the dough. To maximize the efficacy of the fluuidificante the cement grains and aggregates must be already wet at the time of dosing, if the additive were dosed directly with dry solids would be partly absorbed and lose its effectiveness.
For good practice, it is suggested to follow the sequence the steps below:
- 50 kg of sand
- 50 kg of cement
- 10 lt of water
- 0,5 lt of additive
- 175 kg of sand
- 5 8 ÷ liters of water
For the success of the backing layer should note the following:
- during the casting of the slab, the temperature of the same and the surrounding environment should not fall below 5 ° C for a period of not less than 3 days;
- for at least 3 days (In case of low temperatures or slow hardening cements should be a period of time longer) the jet must be protected from drying too fast;
- later to protect the screed from heat or drought in order to avoid shrinkage.
Any holes in the floor must be provided prior to the installation of the plant and the casting of the slab in order to avoid subsequent perforations.
During pouring of the slab, protect the tubes and the insulation from loads important albeit of short duration (eg. create a passage with the boards for wheelbarrows).
Welded mesh reinforcement
It is recommended to lay the body of the screed mesh that allows you to:
- contain cracking during the phases of drying and maturation;
- limit the effects of expansion and contraction due to temperature differences and possible settling due to the insulation below.
For the choice of mesh and the conditions of installation refer to the relevant legislation (for a thickness of screed 45 mm you can opt for welded mesh with mesh 50x50 mm and a diameter 2 mm).
The network must be routed to two-thirds of the thickness of the slab and must stop at the joints.
The reinforcing mesh is placed at a height intermediate in the backing layer.
If you want to do theinsightson heating in the floor, you can findvaluable informationat the following links:
- How much does the system with radiant floor heating
- The advantages of underfloor heating systems for underfloor heating
- Attend a course on radiant floor heating systems