- 1 Cement screed: advantages and disadvantages
- 2 How to make a concrete floor screed
- 3 Order of work
During major repairs, it is usually necessary to replace not only the old doors and window frames, but also the worn-out flooring. However, when installing new finishing materials such as laminate, porcelain tile, or tile, there may be certain difficulties associated with the fact that they can only be mounted on a perfectly flat horizontal surface. But since the subfloor rarely meets these requirements, it has to be leveled beforehand. Align the floor base can be different ways, the choice of the most suitable of them mainly depends on the condition of the floor slabs and the type of the final floor covering, but most often all others use the method of alignment with a cement screed, laid on the screeds.
Cement screed: advantages and disadvantages
- The main advantage of the cement screed – very strong and absolutely flat surface, resulting in its filling, so this method is optimal to prepare the floor base for laying tile and porcelain tiles and laminate.
- The disadvantages of this method include the large weight of the concrete screed, because of which it can not be laid on the weak floor slabs, the labor intensity of work on its arrangement and the duration of drying.
How to make a concrete floor screed
Laying a concrete screed – a time-consuming process, but technically uncomplicated, so to make a floor screed with their own hands on the power of any home master with initial skills to perform construction works. Before you start laying concrete, you should first conduct a series of preparatory operations and get hold of all the necessary tools and supplies. Of the tools will be needed:
- tape measure;
- two-meter construction level;
- trowel width of 0.5 m;
- angle trowel;
- long rule;
- impact drill;
- metal scissors;
- laser level;
- a construction mixer or similar attachment for a drill;
- a wide, large bucket;
- a roll of construction cord;
- paint roller;
- marking pencil.
- special T-shaped perforated plaster profile or steel pipes for making beacons;
- a metal reinforcing mesh with meshes of 40×40 or 50×50 mm;
- dry plaster mix;
- waterproofing mastic;
- self-tapping screws;
- dry sand-cement mixture for rough work.
Order of work
First step. Substrate preparation
- Before making the floor screed, clean the base from construction debris and vacuum it.
- After that, inspect the floor slabs and seal all detected cracks and large potholes with cement mortar. To prevent water contained in the concrete mortar from leaking into the floor slab, cement the joints between the slabs and the walls.
- When the mortar hardens, cover the entire surface of the floor base and the bottom of the walls with waterproofing mastic. Use a paint roller to apply the mastic.
Dries such a mastic rather quickly, so you can soon proceed to the next stage of the work – the definition of the zero level.
The second stage. Definition of the zero level
To properly lay a concrete screed, it is necessary to correctly mark its upper boundary, and to do this, you must first find the highest point of the floor. You can do this in two ways:
- using a laser level;
- using a tape measure and a two-meter construction level.
Method one The easiest way to find the highest point is to use a laser level.
- To do this, assess the curvature of the floor by eye, choose the most protruding part of it, set the laser level on it, turn it on and you will see a red glowing line on the walls. If this line is not interrupted anywhere, it means that you have chosen the right place, but if you can see a gap, move the level to another place and try again.
- Having achieved the desired result, draw it with a pencil – this will be the zero level.
Method two If you don’t have a laser level, use the tried-and-true but more time-consuming method of calculating the highest point.
- On any wall, measure upwards from the floor at a distance of 150 cm and put a point there. Apply a two-meter construction level to the mark, align it strictly horizontally and trace along it with a pencil. Move the level and continue to draw the line along the entire perimeter of the room. When the line closes at the doorway, start measuring.
- At small equal intervals measure the distance from the line to the floor and find the place where the indicator will be the minimum (let’s say, there will be 146 cm). – This is the highest point of the floor.
- Now, at equal intervals, take these same 146 cm down from the starting line, connect the marks with a solid line and you will get the zero level.
Step three. Marking the level of the screed
Given that the minimum thickness of the screed should be 5 cm, from the zero line up this distance and draw through the mark a second line parallel to the first. This will be the level of the screed, on which you will start to set the beacons.
Step four. Installing the beacons
- Place the beacons in parallel rows in a direction perpendicular to the wall with the entrance doors.
- Install the outermost beacons at a distance of 25-30 cm from the walls, and place the rest so that the intervals between them were no more than one meter.
- To simplify the work put the beacons in this way: on the opposite walls, on the line limiting the level of screed, mark the places of contact with the ends of the beacons. Screw self-tapping screws into these marks and string rows of string between them.
- Along the twine at small intervals lay piles of prepared plaster mix, over these piles place the plaster profile with the ridge up and adjust its slope according to the level of the stretched twine. To do this, in those places where the ridge of the beacon rises above the twine, press the profile into the mortar.
- When the plaster mixture has set, remove the twine and begin laying the reinforcement.
Stage five. Installing the armature.
For greater strength, the concrete screed is reinforced with a metal mesh. Cut the mesh in strips of desired width and lay it between the beacons on low supports of plasterboard or plaster mix. It is necessary to make such shoring so that in the process of pouring the mesh was inside the mass of concrete, and not at the bottom of it.
Step six. Pouring the concrete screed
- According to the manufacturer’s instructions, use a construction mixer to mix the first portion of the dry cement mixture.
- Start pouring the mortar from the far corner of the room and pour it in two rows at a time. The concrete mixture is first spread and tamped with a wide trowel, and then flatten the surface of the screed with a rule, moving it along the crests of adjacent beacons, as on rails.
- Meanwhile, your assistant should already be preparing the next portion of the screed, which you will begin to fill immediately after the first one is finished – only then will the screed be strong and uniform.
The time for complete curing of the screed depends on its thickness and the type of materials used.