Technology for laying water heated floors under screed: how to lay, diagram

Laying a heated floor in a screed is carried out in several stages. The old foundation can be destroyed or preserved by slightly changing the technology. It is important to first take measurements and decide on the layout of the pipes. Tips for choosing, as well as step-by-step installation instructions can be found in the presented article.

Laying schemes

The technology for laying a water-heated floor under a screed involves choosing a specific pipe layout. In practice, 3 options are most often used:

1. "Snake" – water moves sequentially from the heater along a circuit folded by a coil. As it moves, it cools down and returns to the source, where it heats up again. Used in corner rooms for uniform heating. Moreover, laying a warm water floor in a screed is carried out from the window or the coldest wall to the warmer one.
2. "Double Snake" differs in that the contour is laid not in a simple, but in a complex spiral, as shown in the diagram. This is an effective way to lay a water-heated floor under a screed. Cooled water moves between the spirals of hot pipes and therefore loses temperature less quickly.
3. Finally, there is another option for laying a water-heated floor under a screed - "snail". Suitable for square or round shaped rooms where an even distribution of the heating circuit is required.

Which pipes are suitable?

A warm floor in an existing screed will warm the room well and last a long time if the pipes are chosen correctly. Their quality, in turn, depends on the material of manufacture:

1. Metal-plastic serve for 20-40 years or longer. At the same time, they are cheap and easy to install. They are not subject to corrosion, the inner surface is perfectly smooth and practically does not become clogged.
2. Polyethylene – are also reliable and wear-resistant, and cost even less than metal-plastic ones. Easy to install, but cannot withstand high temperatures. However, scoring the screed under a heated floor and operating the circuit involves heating the water to only 35-45 degrees - this is safe for any material.
3. Copper pipes are much more expensive than any other, but they can be called almost “eternal”. They are very resistant to corrosion, pollution, and can withstand any temperature and pressure changes. However, due to the high price, they are used extremely rarely in practice. Typically, heated floors are laid under a screed using pipes made of cross-linked polyethylene or metal-plastic.

Laying technology

The technology for laying heated floors under a screed involves the use of a standard set of materials and tools:

• mixture for self-leveling floor;
• soldering iron;
• set of pipes and fittings;
• thermostat;
• cable and wires;
• insulating material;
• pliers;
• knife;
• roulette;
• putty knife;
• level;
• construction vacuum cleaner;
• thermal insulation material;
• damper tape;
• container for preparing the mixture;
• finishing coating.

If you make a floor in a finished screed, you will have to partially destroy it, i.e. perform gating. For this, a hammer drill is used. Since the work is noisy and dusty, you will need protective equipment (mask, respirator, goggles, headphones).

Laying a warm water floor in a screed, the diagram of which is shown above, takes place in several stages:

1. First, unevenness in the rough screed is eliminated, dirt is removed, and sharp edges are smoothed out using a spatula. Clean with a construction vacuum cleaner.
2. Lay thermal insulation material, for example, a cork backing or regular polystyrene. It is secured with dowels or glued on. Lay them overlapping and glue the edges with tape. If the floor is water, polystyrene foam is used, and if it is electric, penofol is used.
3. There is no need to doubt whether a screed is needed for underfloor heating. The heating circuit must be located precisely in the thickness of the concrete. In order for the installation to proceed correctly, damper tape is glued at the points where the walls and floor meet.
4. Now you need to decide on the scheme, i.e. how to lay a heated floor in a screed, for example, with a snake or snail. They make markings and determine the interval. The pipes should be located at a distance of at least 10 cm, but maximum 30 cm. In this case, the bends should be smooth so that there are no sharp turns. Profiles and dowels are used as fastening elements.
5. Next, a metal mesh is laid. If you plan to simplify the installation of warm water floors in a concrete screed, you can install it directly under the pipes so as not to chisel the base. On the other hand, you can put it directly into the finishing screed or use both options at once.
6. Prepare the mixture and begin pouring concrete. But first, water is supplied to the pipes and the leaks are checked, as well as the heating efficiency. The pipes should heat evenly, but not too much.
7. Beacons are placed from a profile or timber at a distance of 50 cm from the wall surface.Pour the concrete mixture from the corner farthest from the door and then move towards the center, towards the opposite wall. During pouring, pierce the mixture with rods to prevent the formation of air cavities.

When installation is completed, it is necessary to allow the concrete to dry for 3-4 weeks. During this time, it cannot be wetted, much less turn on the heated floor. Otherwise, the canvas will not harden, but dry, which will have a bad effect on its qualities. Only after a month can you turn on the heating circuit and use it.