What screed is needed for a warm floor

The technique of laying the roughing type

screed, warm, floor

To the rough screed should be treated with the utmost responsibility, so in advance prepare the tools and materials. The job will require:

  • mixer for mixing the mixture (can be replaced by a drill) and a wide deep container;
  • Trowel, level, trowel and rule to control and ensure the laying of an even surface;
  • Cement, sand and water. materials for mixing.

The following instructions shall be adhered to in the work:

  • If the repair of the room in full, you must first plaster the walls and ceiling. It is important to do this before pouring, since the plaster will fall, and you will have to level the surface again.
  • All drain holes and other fittings are covered with polyethylene or masking tape. If cables are present, fix them clearly.
  • It is required to remove all debris from the floor surface. It is important to remember that even a small speck can lead to subsequent damage.
  • Next, set the beacons, which are fixed with alabaster.
  • Prepare the mixture for pouring. combine cement and sand in the proportion of 3:1. Add water to form a thick mixture and plasticizer according to the above recommendations.
  • Between the screeds immediately pour the prepared mortar, distributing it evenly and evenly over the surface. The mixture must be tamped to release air. If it remains, when it dries the layer will crack.
  • The rule is used, with which the surface is leveled. The movement should be wavy, on itself.

Then the room should be closed. An important condition here is the absence of light and drafts into the room. After a day, polyethylene is placed on the floor, with which the drying rate is increased. Leave the material to dry completely for several days.

Attention! It is better to keep the bottom layer for 3-4 weeks to dry, if the above technique is used. This will provide a degree of assurance against cracking.

What do you pour underfloor heating?

The basis of the construction mix for the screed is cement. It is recommended to add plasticizers, to facilitate the laying and leveling of the surface. Using plasticizers increases the density and strength of concrete, almost no small voids and cracks. If you add to the mortar plaster “to speed up the process,” the quality of the screed is much worse, so it can not do.

Screed performs from the cement-sand mortar, use sift or self-leveller.

What is a screed and its purpose

Laying screed is a universal preparatory work. They allow you to level and strengthen the surface of the floor to make additional sound insulation, keep the heat inside the room, fill the voids and prepare the floor for further work.

Material for pouring is made of cement-sand mixture, concrete, gypsum, expanded clay or fiberglass. Each of them has its own advantages and disadvantages. According to the method of application compositions are wet, dry and semi-dry. Plasticizer is necessarily added to the mixture, which makes the filling more even.

Additional functions of the mortar. protection of the floor heating structure (heating elements) from mechanical impact and damage, the direction of heat in the right direction, reducing heat loss.

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For proper heat distribution under the pipes of the heating system lay a reflective material. It directs heat upward without heating the bottom of the “pie”.

Brief description of the “pie

Underfloor heating can be laid on almost any substrate: concrete slabs, wooden lagging, soil, etc. д. The most common sequence of laying materials (“pie”) looks like this:

  • Subfloor (concrete, wooden, screed floor).
  • Damper tape around the perimeter of the room (to compensate for thermal expansion).
  • Moisture insulation.
  • Heat insulation supplemented with a reflective surface (e.g., Styrofoam).
  • Mesh for reinforcement.
  • Heating pipes.
  • Screed.
  • Carpet pad (if required for the finish coat).
  • Flooring (tile, laminate, etc.). д.).

Laying the heating system on the ground and wooden lag is different preparatory work (additional layers underneath). The thickness of the entire pie is 15-18 cm depending on the materials, pipe diameter and the top layer of the filling.

Concrete screed of the warm water floor

Concrete screed is based on sand and cement M400, to which is added crushed stone. Mortar proportions: 213,8. Disadvantages of concrete screed:

  • mortar is quite heavy and can cause damage to water pipes;
  • Air bubbles appear in the intermediate layer due to the impossibility of tamping, which affects the quality of the concrete layer;
  • The intermediate layer is difficult to level and requires additional levelling.

Between the concrete screed and the walls of the room as insulation glued damper tape.

Principles of using the cement-sand mixture

Cement-sand mixture is prepared from a mixture of cement and sand in the ratio of 1 to 3. To improve the properties of the filling, plasticizers are used in the proportion of 0.9 kg per 1 cubic meter of mortar. Plasticizers increase the plasticity and fluidity of the mortar, and prevent it from cracking during expansion.

For the composition of the apartments and residential buildings are used cement grade M200. For flooring garages use mark M400, but also allowed the mark M300 and M500. Between the cement-sand composition and the walls of the room, as well as for concrete pouring, lay a damper insulator.

Further information! Between the composition of cement and sand, a dense polyethylene film is laid on the base, which is covered from above with a layer of thermal insulation.

The thickness of the cement-sand layer for even heating should fully cover the pipes, otherwise the heating will be streaky.

Types and composition

Screeds can be dry, semi-dry, and wet. Dry screed is plywood, gypsum board sheets and chipboard. To accommodate the underfloor heating system use wet and semi-dry type.

Wet screed is made from a mixture of cement with sand and gravel, diluted with water to the desired consistency. Sometimes a little bit of expanded clay and gravel is added to the mortar. The brand of cement for the preparation of the mortar should have a quotation not lower than M300. Instead of sand, it is better to use sift: it provides a higher adhesion and prevents delamination and cracking. When preparing the composition requires the use of plasticizer at the rate of one liter per square meter of filled area, which will reduce the final thickness of the screed to three centimeters. Cement screed is suitable for all kinds of underfloor heating.

Semi-dry screed is performed with dry mixes and does not require pre-levelling of the rough floor. No cracks and no shrinkage or deformation during drying. This composition hardens much faster than concrete, and the short setting time and a small amount of fluid required will prevent leaking of the mortar to the lower floor.

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Semi-dry and wet screed are floating and stationary. The first type is used when it is necessary to lay thermal and waterproofing. As a result, the layer has no direct adhesion to either the floor or the wall. The thickness of such a floor must be at least 3.5 centimeters and have a multi-layer structure. Floating screed is also used for pouring over soundproofing material, which consists of mineral wool and is covered with a waterproofing film on top.

Stationary screeds are formed without the use of insulation.

Tile adhesive is used as a screed when installing an electric floor under the tiles. It aligns the surface well and dries quickly. If you need to repair such a screed is much easier to open than a concrete screed.

Screed for a warm water floor: installation rules

High-quality underfloor heating can not be done without proper installation of screed. In addition, you will need to buy a modern floor covering, materials for the creation of the pipeline and components of the mortar for pouring. Failure to comply with the technology of the work leads to the fact that the screed for a warm water floor has defects and all efforts aimed at heating the room are in vain.

If professionals from a construction company are invited to install the system, the homeowner would do well to know the basic rules of its creation to ensure that the service is done properly. Property owners, after reading the relevant information, have the opportunity to exercise direct control over the construction work and, if necessary, point out shortcomings, demanding the elimination of errors.

Screed under a warm floor: types and methods of pouring

In recent years, underfloor heating has become very popular, gradually replacing traditional heating systems. There is a wide range of such options on the market, each of which deserves separate attention. But no matter what variant of the floor heating you have chosen, you must first decide on the organization of the screed, since this is one of the most important stages of the installation of heating.

Installation for electric heating

Account should be taken of the minimum thickness of the screed, which is above the heating cable (and under it). There are several ways to install. It is necessary to prepare a solution, and only after that to engage in pouring the surface.

Careful implementation of all rules will help to avoid cracking of the coating, and heating will be the same throughout the room, and the system will serve for a long time.

What should be the thickness?

The thickness of the screed directly depends on the choice of heating element and the initial condition of the surface on which it will be laid.

In the absence of a level of strict horizon will be necessary to make rough screed. Its thickness depends on the deviation of the floor surface from the level and is individual for each room. If the surface on which the floor heating is installed, has a slope, the heating elements will be at a different distance from the surface of the screed and the flooring. The result will be uneven heating of the room and heat loss. It is clear that if a rough screed is necessary, the size of the so-called “pie” and the material consumption increases.

How to floor screed with sand and cement. Beginners guide- plastering Guru

Below is a calculation of the thickness of the “pie” when installing water underfloor heating and the presence of a horizontal surface. Waterproofing film has a thickness measured in microns, so it should not be taken into account. Polystyrene boards are used with a thickness of 60 mm (2×30) and more, depending on the climatic characteristics of the region of residence. Thermal insulation metal material should be at least 3 mm, the mesh for screed reinforcement and fixing the heating elements. from 5 mm.

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Taking into account the overlap of one bar on the other it takes 10 mm. The diameter of the element itself varies from 16 to 25 mm, the minimum height of the screed beacon is 10 mm.

Based on the figures above, the thinnest “pie” will turn out a thickness of 102 mm, of which the screed itself will take 46 mm. From experience, this screed is thin for water flooring and may deteriorate during use. Therefore, many masters prefer to use starter profiles for installation of drywall with dimensions of 27×28 mm instead of buying ten millimeters screeds. they are stiffer and higher than standard screeds.

Screed thickness increases to 60 mm and can withstand any loads.

The technology of laying mini-mats on the glass mesh is different in that there is no need for a reinforcing metal basis and a thick screed on top. In addition, plates of extruded polystyrene can be used in a smaller thickness. Therefore, the minimum thickness of the “pie” will be 60 mm, and directly screed. 17 mm.

But this is acceptable only in the case of subsequent laying of ceramic floor tiles on its surface, which will provide additional rigidity to the floor. If you plan to cover the floor in the form of linoleum or laminate, it is desirable to increase the screed to 25-30 mm, which is the maximum value. Mixing proportions are chosen individually.

For the film warm floors instead of the screed use plywood or OSB boards. Manufacturers claim that the screed is not necessary. Its advantage is much less inertia, as heat loss on heating a thick screed will be less. True, the floor will also cool down almost immediately after you turn off the thermostat.

The advantage of infrared membrane floors is that they do not dry the air. When drafting the floor project does not take into account places in the rooms where there will be furniture, standing in one place. Under cabinets, drawers, sofas do not lay the film to avoid deformation. From the walls and heaters should be at least 20-30 cm.

Installation of the film warm floors begins with laying of a heat-reflective foam material for which it is very important not to conduct a current. After laying all the elements in accordance with the project, connecting the temperature sensor and the thermostat, you can lay the laminate floor without pouring screed. To waterproof and prevent moisture from getting onto the electrical contacts, you should lay a PVC film before laying the flooring. If you plan to lay tiles, it is better to protect the floor elements with either plywood, OSB, or cement-bonded particle board. You can also protect all connections very hermetically.

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