Screed Thickness Above Water Underfloor Heating

The thickness of the screed under the warm floor depends on many factors, but it should be the same over the entire surface. The arrangement of the water floor is carried out in several stages, where the organization of hydro and thermal insulation is mandatory, reinforced mesh layingpipes and screed device. The last stage of work requires repairmen to take special responsibility and adherence to technology, because of this the protection of the heating system and the preparedness of the surface for laying the final, decorative coverings. It is a suitable screed thickness that provides strength and uniform floor heating.

General principles for calculating the size of a concrete screed layer

A cement screed, which is located above a warm water floor, is not just a layer of mortar. It provides the necessary pressure to the pipes for crimping and their reliable protection against mechanical damage, and also contributes to uniform floor heating. In the process, it is very important to correctly calculate the thickness of the screed for the optimal functioning of the entire heating system. What should be considered in the calculation process?

• The thickness of the screed is determined not by the wishes of the apartment owners, but by many other factors - the structural features of the building. It takes into account the thermal power of the surface, the properties of the overlap, the type of facing material, etc.
• The screed allows heat to be evenly distributed over the surface of the floor; too thick layer provides greater heat capacity, thin - heats up quickly. But in the first case, the surface warms up for a long time, and temperature adjustment is difficult. A thin layer guarantees quick heating of the floor, but it is too prone to cracking and cannot provide an even supply of heat.
• The organization of this heating system involves coating with a solution of all heating elements. Optimum is the total thickness of plus or minus 65 mm.

How to calculate the thickness of the screed?

The thickness of the screed over the underfloor heating is such that there is a layer of solution of at least one centimeter above the pipeline. This is necessary to prevent cracking of concrete. The calculation is based on the diameter of the pipes of the heating system. So, when using standard pipes with a diameter of 20 mm, the optimum thickness will be 40 mm, where 20 mm is placed on the pipeline, and the remaining 20 mm above it. Correct calculation provides not only uniform heating of the surface with heat accumulation in the base, but also eliminates the strong deformation of the outer layer from uneven thermal expansion.

When using pipes of this size, it is possible to allow an increase in the thickness of the finish screed by another 10 -20 mm. That is, its size should not exceed 60 mm, otherwise the organization of a warm floor system will be inappropriate in terms of efficiency. A lot of energy will go to warming up a thick concrete layer.

The thickness of the screed also depends on the purpose of the room. The minimum mortar flow rate is required for residential premises, and in shopping pavilions, warehouses or car centers, the thickness of the concrete surface above the pipes should be greater. This is due to excessive load on the floor surface, as well as the fact that public buildings do not need the same heat transfer as in the case of residential buildings. The thickest screed - more than 30 mm above the pipeline is used in aircraft hangars.

What else should be considered when calculating the thickness of a concrete screed?

A screed on a warm water floor can be reinforced if you plan to place large objects in the room. For example, installing a piano will require placing a metal mesh in the top layer of the screed, which can be located pointwise or over the entire surface. Special solid additives in the form of fractions can increase the strength of the screed, as well as mixtures for self-leveling floors, which allows to slightly reduce its thickness. Therefore, in the standard calculation of the layer of screed over the pipes in the amount of 40-50 mm using the above means, you can leave its thickness from 20-25 mm. You should not save on materials for organizing the final layer of the warm floor - subsequently this will negatively affect its strength and heat transfer to the heating system.

To calculate the volume of the screed, calculate its thickness and multiply the resulting figure by the area of ​​the room. Fractional particles are polypropylene chips and fibers, which contribute to good floor strength and are often used by craftsmen in the process of organizing warm floors.

On a note

• Before embarking on concrete pouring, it is necessary to check the operability of the underfloor heating system and its hydraulic density.
• To avoid excessive heat loss, do not ignore the laying of heat-reflecting material under the piping system.

• The efficiency and economy of all heating is affected not only by the thickness of the screed, but also by the quality of the materials used. This is especially true for cement, which has the property of caking. Carefully approach the selection of materials and purchase cement only immediately before starting work.

After pouring the solution, give it a sufficiently long time to dry. A thick screed under the water floor dries on average up to one and a half months, and only after it has completely dried can you proceed to laying flooring. To prevent cracking of the concrete layer, it is necessary to moisten it with water 2-3 times a day for ten days. Adequate moisture during drying will prevent cracking of concrete and allow the cement to gain the necessary strength.