Which Floor Screed Option Is Suitable For A Water-type Heating System

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-08-25 07:54

• The need for screed
• Screed types
• Preparing the base for underfloor heating
• Expansion joint
• Purchase of material
• Screed thickness
• The composition of the grouting solution
• Pouring screed on beacons
• Expansion joints
• Self-leveling mixtures
• Expert advice

Deciding to install a warm water floor in the house is the most correct one. This creates great comfort and coziness. With it, you can walk barefoot on the floor and not be afraid of the cold. But before laying, you should choose the right screed option for it. Efficiency will be reduced due to a large fill layer, and very thin in this case will quickly crack and lose all its qualities and properties. Therefore, the screed must be of high quality and meet all the requirements of reliability and durability.

The need for screed

Installation of the heating system cannot do without a reliable screed.

The ready-made solution fills all voids and reliably protects them from external influences and possible mechanical damage. Heat is not lost, but everything is completely transferred upstairs, from floor to ceiling.

If you add special additives, plasticizers to the concrete solution, then they will avoid the appearance of bubbles after pouring. Due to this, the density of the screed increases, as well as the thermal insulation properties of the material. The outer part will be used for finishing or decoration.

The underfloor heating screed, in addition to the protective function against damage to the pipeline, performs the function of even distribution of heat throughout the entire room where the installation is performed. Additionally, it supports soundproofing of downstream rooms.

Screed types

There are several main types of screeds that can be used to create a warm water floor:

1. Cement and sand. The concrete screed of a water-heated floor, which has a similar pouring technology, has almost identical qualities.

   

   To prepare the solution, sand and cement are used as the main components, and various additives can also be used that improve the quality of the entire filling. It is not uncommon for PVA glue to be added to the composition of the solution, which increases the plasticity and excellent spreadability over the surface.

2. Self-leveling mixtures. They are most often used for finishing and creating a perfectly flat surface.

3. Semi-dry screed. The technology is characterized by a small amount of water.

   

First, it is worth deciding which screed of a warm water floor will be optimal for certain conditions. Everything will depend on the degree of unevenness of the base, the complexity of the installation process and other factors.

Preparing the base for underfloor heating

When a concrete screed is selected for execution, it is very important to carry out a number of preparatory measures here. The surface must be level with a horizontal level. This is especially true for areas where there are height differences of more than 10 mm. We must not forget about the waterproofing layer. A damper tape is fixed along the wall along the entire perimeter of the room, which serves to compensate for the temperature of the future screed. When heated, the solution has properties to expand. To prevent damage to the walls in this case, a damper tape is used.

In a warm water floor, several circuits can be used to improve the quality of space heating. In this case, the damper tape should be laid along the line between them.

The base of the floor must be properly insulated so that the heat does not rush down under any circumstances, but only flows through the floor into the room to warm the air. Insulation will depend on the location of the room, depending on the scheme itself and the use of a warm water floor as the main or additional source of heating.

When the warm floor acts as an additional element of the heating system in the house, then foam polyethylene is usually used as the material. In addition, it must have a foil coating that will reflect all the heat from the heating elements towards the floor.

The first floors of buildings, if there are also basements without heating, as well as when the premises of the house are located directly on the ground, it is best to purchase more serious insulation - expanded clay mound, expanded polystyrene with sheets from 50 to 100 mm thick. This will significantly reduce heat loss.

When a warm water floor is arranged in rooms on the second floor and above, as well as on the first, if there is a basement with heating, then polystyrene foam can be used for thermal insulation. An alternative to such products is extruded polystyrene foam. Usually choose a thickness from 20 to 50 mm. You can choose other options for insulation, the main thing is that the thickness is appropriate.

There are also special heaters on the construction market, which are intended directly for the installation of warm floors. They have special channels on one side, where the pipes of the system will be placed. The entire installation process will be much quicker.

In the absence of special channels on the insulation, floor heating pipes can be fixed with clips and clamps to the reinforcement layer. It is usually made of a metal mesh with corresponding cells in diameter. The used screed for warm floors has its own advantages, due to which it is in demand in the construction industry.

Expansion joint

When pouring a screed for a warm water floor, we must not forget about the device of the expansion joint. It can be performed in the following cases:

1. If you have a room with a complex configuration.
2. In the openings of entrance or interior doors, or rather, under the location of the threshold.
3. When the wall is very long, more than 8 meters, and also in cases, the ratio of the width of the entire room to its length is less than 1 to 4.

It is possible in other cases to arrange expansion joints at this stage, the main thing is that everything brings a positive result as a result. In this case, the main thing is to choose the correct seam height. It must correspond to the selected thickness of the concrete screed, which is selected for pouring under the warm floor. Attention is drawn to the fact that the upper part of the expansion joint, its border, should be located in the place where the finishing floor covering will be located in the room.

It is worth noting that there are nuances when laying a mesh for metal reinforcement in a screed of a warm water floor. It must, under any circumstances, be interrupted at the place where the expansion joints in the room will be located.

Purchase of material

Underfloor heating screed must be carried out in the presence of certain materials. They can be purchased at any hardware store. It should be understood that one set of products will be required for the screed, and another set will be needed for high-quality installation of a warm water floor. When choosing, special attention should be paid to pipes. The efficiency of the entire system after installation will depend on their quality. Some are of great value, like copper or stainless steel, but at the same time they have a sufficient set of positive qualities and characteristics. If the choice fell on polyethylene pipes, then financial investments will be at a minimum. But certain difficulties may arise during the installation work.

Screed materials will depend on which option is chosen for execution. This is cement with sand, backfill with sheet material, or special construction dry mixes, which just need to be diluted with the required amount of water. You should understand and know after you have decided on a screed for a warm floor, which materials and equipment are better to purchase.

Screed thickness

All the manifested qualities of the heating system will depend on the thickness of the floor screed. Usually, for the rough version, a thickness corresponding to 50 mm is chosen. The thickness will be influenced by the purpose of the room itself, where the screed is made under the water floor.

Residential premises allow for a layer of 50-70 mm, and industrial facilities, due to high external loads, must have a screed even up to 100 mm.

In this case, one should proceed from what the screed for a warm water floor is generally intended for - heat accumulation. This already suggests that a thin layer of screed will not be able to retain heat for a long time. Consequently, the system will continuously operate and transmit energy. Boiler operation will increase to maintain the required temperature. The optimum screed thickness for a warm water floor is 70-80 mm. This will be enough to have optimal heat levels in the room.

The composition of the grouting solution

For a heated room from the base of the floor, you will need to carefully prepare the solution, in compliance with all proportions. In order not to waste time on this, you can buy a ready-made mixture and add a certain amount of water to it, following the guide and instructions. The concrete used must have a grade within the range of M150-300. Everything will depend entirely on the loads created during the operation of the base under the warm water floor. In residential construction, M200 will most often be sufficient, but industrial facilities require M300.

When making the mixture yourself, you should adhere to the established proportions. 1 part of purchased cement should be mixed with 3 parts of sand. For sand, a fraction of no more than 0.8 mm is taken, so that the solution spreads better over the surface and does not create unnecessary irregularities after pouring. An alternative to sand is granulation, which creates a more durable mortar. But then the proportions will also change, instead of three parts of sand, you will need to add 6 portions of granulation. We must not forget about water. As a result, you should get a liquid consistency of the solution. Usually they take 0.8 parts.

Plasticizers will allow the screed to become more elastic, which will be especially evident when heated. If there is no desire to visit stores and at the same time spend money, then there are folk remedies that can replace them:

• PVA glue. One bag of cement will require 1 kg of glue.
• Liquid soap. A smaller amount is added, in the order of 150 grams for each bag of cement.

Pouring screed on beacons

When the surface is ready for work, you can pour the mixed solution. But at the same time it is worth remembering that it is necessary to set the beacons according to the level in the room. Only in this case the screed under the warm water floor will be of high quality. The most optimal option in this case is the usual mortar mounds, reaching the level of the entire fill. The whole process is very easy and not difficult even for a novice builder. The main thing in the work is to use the appropriate tool to obtain the horizontal level. There are also ready-made lighthouses on sale, which you just need to place on a plane in the room.

After pouring concrete for underfloor heating screed should be tamped. For this, there is special equipment that can even be rented to perform work of one-time value. Thus, air bubbles are expelled from it. If this is not done, then the level of thermal conductivity of the future warm floor will decrease. That is, the process itself does not require significant knowledge, but only the application of labor. In a similar way, the screed is installed in its final form already immediately after the installation of the elements of the warm water floor. Already in the final version, it will be necessary to arrange the expansion joints.

Expansion joints

All seams must be made in rooms with a large area of more than 40 square meters. To be on the safe side, this is done in smaller rooms as well. The seams are designed to prevent the appearance of cracks on the surface during the operation of the warm water floor system and the supply of elevated temperatures. In addition, defects can affect the quality of the floor covering.

There is no need to install expansion joints in a rough fill. This is based on the fact that a layer of insulation is located between it and the underfloor heating system. In simple terms, the seams are a damper tape, which is only located in the middle of the room in the screed.

Self-leveling mixtures

Self-leveling mixtures can be used for the underfloor heating system. In this case, you do not need to install the guides.

After fixing all the components of the warm water floor system and cleaning the surface from debris, it is fashionable to fill with a prepared solution. The main thing in this case is to strictly observe all proportions in order to obtain a high-quality surface. The layer thickness over the pipes must not be less than 30 mm. It is best to use a wide trowel to spread the mixture evenly over the surface.

They can be used in exactly the same way under a warm water floor system to create a flat surface under the contours of the pipeline.

Expert advice

During work on the installation of a screed for a warm water floor system, you should adhere to the technology of the device, as well as advice from experienced craftsmen. They have faced problems more than once and will help solve each of them.

It is best to start the underfloor heating screed after all the plastering work on the walls in the room has been completed. At the same time, we must not forget about the fastening of the damper tape, which does not allow the entire "pie" to collapse during the operation of the warm water floor.

Before preparing the solution or mixture for pouring, the beacons should be level. This will allow you to achieve an ideal horizontal surface for the subsequent installation of the entire heating system in the room.

When the room has a significant area, then it is worth considering how to arrange expansion joints, which are the same damper tape, but around the perimeter of the room, and approximately in the middle.

Having considered all these device options, you can decide what kind of screed you need for a warm floor. All factors should be foreseen before starting work, so that later there will be no difficulties and problems.

If you fully follow the technology of pouring the rough screed, further installation of the water floor heating system and the final screed for the floor, then the result will be the most joyful - the heat will flow into the room from the very base and it will be comfortable to walk on the floor even with bare feet. This will be felt to a greater extent at the moment when you enter the room from a cold street and feel the influx of heat.

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