How To Choose The Right Dimensions For All Layers Of A Warm Water Floor

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

• Common features
• Screed varieties
• Minimum rates
• Maximum limits
• "Pie" underfloor heating
• Fill tips
• Manufacturer recommendations

For a warm floor, in the end, in any case, you will have to arrange a topcoat, including a screed. Self-leveling mixtures and mortars on a cement-sand base can be used in their capacity. Everything will depend on the financial capability and the chosen device option. In any case, the surface should be perfectly flat, including relative to the level of the water floor heating contour. In this case, the heating of the subfloor will be uniform over the entire surface in the room. In this case, it is worth paying attention to one very important point, which is the optimal thickness of the future screed.

Common features

The thickness of the screed for a water-heated floor will affect the efficiency of the system, its efficiency, as well as the operational period. A thin layer will not allow the base of the floor to evenly warm up, and besides, such a screed will crack very quickly due to constant temperature changes. The selected floor covering will also deteriorate very quickly on a very thin screed.

But even thick layers of fill will not bring a positive result. With such a basis, heating costs will increase significantly, since a lot of energy will have to be spent on heating the entire resulting "pie". Therefore, it is necessary to choose the optimal indicators of the level of pouring concrete screed for a water-heated floor system. But even experts will not be able to give an answer about the versatility of the thickness of the pouring solution. Many conditions can influence this parameter:

• Type of subfloor, type of soil. To a greater extent, this applies specifically to private construction when arranging a room with a concrete floor from the very foundation.
• The parameters of the entire room, where the screed is arranged over the warm water floor, its configuration.
• The purpose of the future premises.

These points are among the main ones. Additionally, there may be a few more nuances that should be paid special attention to. They can be referred to as the marking of the cement used, the choice of a specific mixture for the job, the reinforcement and its characteristics, etc.

Screed varieties

In total, there are three main types of screeds that can be used to create a flat surface on top of the mounted water heated floor. But even this classification is considered conditional.

1. The thickness of the underfloor heating of the water floor, or rather the screed over the entire system, is in the region of 20 mm.

   

   This is more than the minimum indicator for pouring over the contour of the underfloor heating pipeline. Self-leveling mixtures are most often used in work, which allow you to get a really thin surface that can withstand heavy loads and mechanical stress. This stage is arranged without using a layer of reinforcement or a reinforcing mesh.

2. Average fill level indicators, which fluctuate within 70 mm. Additionally, to give the structure strength and reliability, a reinforcing mesh or special meshes are used to reinforce the screed.

3. The maximum limits of the level of the future screed through the pipes of the warm floor reach 150-170 mm. The system is called monolithic, in which reinforcement is mandatory. Suitable for cases of the device of an integral support system, which acts not only as the base of the floor, but also as the foundation of the future structure. In this case, you should first find out what kind of loads the overlap in the house can withstand.

   

But all indicators cannot be attributed to the minimum or maximum value of the screed fill level. After all, if crushed stone is additionally used in the work, then forget about the threshold of 20 mm. The final thickness of the underfloor heating will be much greater. Self-leveling compounds are usually used just before flooring. It must be done in such a way that the entire contour of the warm water floor was covered with a screed. This suggests that when choosing pipes with a diameter of about 2.5 cm, a filling layer of 50-70 mm will be enough. It is up to 50 mm that the screed thickness should be above the laid pipes.

Minimum rates

According to generally accepted standards, there are minimum indicators for the thickness of the screed over a water-type floor heating system. According to them, in the case of using self-leveling mixtures, as mentioned earlier, the screed must be at least 20 mm. But if a solution of sand and cement is being prepared in the work, then at least 40-50 mm. In the latter case, this applies to pouring without an additional layer of reinforcement. If you make it smaller, then these parameters, then it is unlikely that it will be possible to achieve the efficiency of the system, as well as to obtain the desired characteristics.

There are several cases in which you can think about the minimum values of the level of the screed above the warm floor. Without fail, a sub-floor must be arranged, which leveled the base to a horizontal position. All significant irregularities are thus eliminated and it remains only to create a layer above the contour of the warm floor. In addition, there should be no reinforcement elements in the entire structure. This will only increase the overall fill layer. Instead of reinforcement, there is a modern means for imparting strength and fluidity to the solution - fiberglass. It has a lot of positive qualities that are worth paying attention to.

If, at the same time, in the room in the subsequent operation, significant loads will be created on the base of the floor, then the minimum values of the screed thickness should go to the side. Such premises can be considered corridors, bathrooms, toilets, kitchens, any technical premises.

Building codes state that underfloor heating pipes will most efficiently transfer heat to the interior if there is a 65 mm screed along with the floor covering.

Maximum limits

No standards are provided for filling the screed to the maximum. Technologically, it can be arranged to a height of 10-15 cm. If you make the layer larger, then it will not bring any efficiency. All the work done will be meaningless. But such a screed can only be performed in exceptional cases. Such situations can be the following points:

• If the layer being arranged acts not only as a filling of the screed, but also as the foundation of the structure.
• Devices for pouring concrete floors in rooms with significant loads (garage).

• Installation of screed on problem soils, which is more suitable for private houses.

  

If the subfloors have significant differences in height, then some performers decide to fill as much as possible in order to bring everything to a horizontal position. But there is no expediency in this. It is best to pre-fill with dry materials (expanded clay), and then fill the solution. Such actions will save time for work, as well as money for materials. True, this is all best done before installing a water-heated floor. The heating main requires a flat surface to distribute heat evenly over the entire subfloor in the room. If there are large protrusions above the surface, they can be completely knocked down with a hammer or other equipment.

A large amount of poured concrete will be wasted. If we have a room of 10 square meters, and the screed layer is only 100 mm, then at least a cubic meter of concrete will be left, and these are unjustified costs.

Other difficulties may appear with a thick screed over a water-heated floor:

• Long period of surface heating.
• Decrease the efficiency of the system.
• The cost of heating the room will increase.

This all suggests that you should choose the optimal screed thickness for a warm water floor, so that all the characteristics of the system are manifested and well maintained throughout the entire service life.

"Pie" underfloor heating

The "pie" of the warm floor, and, therefore, the total thickness includes other parameters, in addition to the screed itself:

1. Thermal insulation. Most often, polystyrene is used as its quality. The layer is necessary in order not to waste excess heat, not to give it down, but to redirect it to the base of the floor. The system becomes less expensive and more efficient. If these are cold regions, then the optimal polystyrene thickness should be about 100 mm. In warmer conditions, 50 mm will suffice. Much will depend on the location of the room (above the basement, heated room, etc.).

2. Waterproofing. In the total thickness, it may not be taken into account at all due to the fact that most often it is an ordinary polyethylene film.

   

   Its thickness is so insignificant that it makes no sense to take it into account.

3. The MAK grid allows you to efficiently and evenly distribute the pipes of the warm water floor. Its optimum thickness is 4 mm. But it can be dispensed with if mounting mats with corresponding protrusions for the underfloor heating contour are laid under the system.
4. The pipe used. It is from her that the heat will spread throughout the entire base. Usually its height is no more than 20-25 mm, depending on the diameter of the inner part.
5. Concrete screed. To prepare the solution, it is best to make a not very strong solution up to the M300 brand. The filling level should be measured from the top of the laid pipeline. In this case, the warm water floor system will work with the greatest efficiency.

6. Finish coating. In addition to the flooring itself, glue is added to the total thickness if it is a tile.

   

It is possible to make certain preliminary calculations for the screed thickness for a water-heated floor, depending on the chosen flooring option. For thermal insulation, 50 mm will be enough, unless it is a cold region of the country. The pipe, together with the MAK mesh, necessary for reliable fixation of the contour, will take on average 25 mm. Everything will depend on the diameter of the pipeline. In some cases, the MAK mesh will not be needed if mounting mats are selected specifically for flooring under a warm floor. The optimum thickness of the entire screed is 50 mm, and for the final coating, about 20 mm will remain. In total, we get that the total thickness of the system will be in the range of 140-145 mm. Such a layer is necessary for the device on the first floor of the house. If this is the second and subsequent floors,then there will be some reduction in the structure due to a smaller layer of insulation. A lot of it is definitely not needed there.

Fill tips

To pour the screed on the water floor heating system, you should follow the recommendations from specialists with experience in performing this type of work. First of all, it concerns the cement grade, which in the optimal mode will be equal to M200-M300. Various additives to the composition of the solution will not be superfluous to improve the quality of the filling. The plasticizer will allow the mixture to spread perfectly over the entire surface and, as a result, avoid the appearance of cracks and other defects.

After pouring, time must be kept until the solution is completely dry. During this period, it is impossible to turn on the water heat-insulated floor, as it will have a negative impact on the drying process and the quality of the screed. To make the base strong, you should take care of the screed after pouring. This consists in maintaining optimal temperature conditions, eliminating drafts, and moisturizing the surface for almost a week.

Do not heat the "warm" floor in order to speed up the drying process. If the deadlines are tight, then it is better to use other options for the device of the sub-floor, such as self-leveling mixtures, where it takes about 9-11 days to dry. At the time of screed installation, the ambient temperature must not fall below +10. Otherwise, it will not be possible to get a positive result.

We must not forget not only about the damper tape, which serves as a compensator for the thermal expansion of the screed, but also about all the other layers that will create a reliable structure over the warm water floor system. Before starting the filling, measures should be taken to check the system for operability and the tightness of all connections. Otherwise, difficulties may arise after switching on in the screed.

Manufacturer recommendations

Each manufacturer evaluates its mixtures and other materials differently for the construction of the underfloor heating circuit itself, as well as concrete screeds. In addition, they put forward their recommendations for choosing a high-quality and optimal level of filling so that the system has the greatest efficiency.

Rehau. For them, from the top of the pipe of the underfloor heating system, the thickness of the solution must be maintained within 45 mm. And the whole structure is no more than 61 mm. Therefore, it is necessary to correctly select the required pipeline diameter for the entire filling. But when it comes to industrial premises and the presence of constant maximum loads, then the minimum concrete screed should be 75 mm and reach a maximum of 92 mm.

Kan. It is also a German manufacturer. They also indicate the need to pour the solution along the upper edge of the pipes of the warm water floor system to a height of 45 mm. If we consider these indicators directly from the thermal insulation, then 65 mm. You can turn to the products of this company and add their proprietary plasticizer to the solution. In this case, the height of the concrete screed can be reduced to 25 mm. The catalog displays all the recommendations depending on the material used and the total area.

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