Self-leveling Concrete Floors: mix selection and necessary tools
Self-leveling concrete is a special kind of concrete that’s usually used for indoor concrete surfaces. It’s extremely important for indoor concrete surfaces to be perfectly flat so that some sort of interior floor covering, that is usually installed on top of it, can adhere more effectively and look nice. Our company’s top priority is to do every job the best way possible, and we often use self-leveling concrete to get the job done to your satisfaction. It has become very popular in modern interior designs as its perfect flatness allows it to work well with even the most delicate floor coverings.
Self-leveling concrete is at least of the same quality as the traditional concrete, but it’s usually more advanced and even more durable. And just like the regular concrete, it can be done in a decorative version as well.
The cost of self leveling Concrete for floors will be from 0,50 dollars per one sq. ft.
Self-leveling Concrete Floors for concrete screed
Self-leveling screed yourself – it’s easy
Self-leveling Concrete Floors are famous for being very easy to fill. To do this, you do not need to have extensive experience in construction. In addition, this type of screed allows you to achieve a perfectly flat surface, which is ideal for any type of coating. But few know how to properly prepare and apply self-leveling mixes to the floor.
About Mix Selection for Self-leveling Concrete Floors
Most self-leveling screed mixes are cement based. Gypsum is also used. In the composition of such mixtures there is sand or limestone. In addition, in modern mixtures there are plasticizers, components that hold water, improve strength and other characteristics.
As for the choice of composition for Self-leveling Concrete Floors, the following criteria should be followed:
- Humidity. If the room was and will be wet (nothing can be done about it), it is necessary to use exclusively cement-based mixtures. If the room is dry, you can buy both gypsum and cement compounds;
- Base. If you have to deal with a concrete, sand (using cement) or anhydrite base, it is better to buy special mixtures. Such are produced, for example, by the trademark Ceresit;
- Dates. If the time is running out, you can buy the so-called mixture for urgent repairs. Their main feature is that they can dry in just 6 hours (some in 10, which is still very fast);
- The required layer. The standard height of a layer of a self-leveling mixture is 1 cm. But there are special mixtures that allow you to make a layer of 8 cm or more. An example is Ceresit Moment Smooth floor;
- Estimated screed coverage. If in the future it is planned to paint the screed, it is best to take self-leveling mixtures of the Horizont brand. Judging by the reviews, they are the best for paintwork;
- Insulation required. In those cases when it is necessary to achieve high noise insulation and heat preservation, it is better to use Bolars mixes. If fire resistance is important, buy KNAUF mixes.
There are a huge number of manufacturers of such mixtures, but while in the store, be sure to pay attention to the characteristics of each of them. Typically, the bag describes all the features of each mixture.
Suppose that in our case the humidity in the room is normal and the height difference in the room is 0.5 cm. Then the required screed layer will be 1 cm. The base is concrete, the deadlines are not running out. Linoleum will be placed on the screed; increased insulation is not required. In this case, we need to pay attention only to the thickness of the layer (indicated on the bag). Take one of the most popular blends, Thomsit DD from the Ceresit brand.
As you can see, the layer thickness and characteristics are indicated directly on the bag (in the lower right corner). It says that the composition is environmentally friendly, suitable for internal work and more. In the same way, it is indicated on the bags that the mixture has increased sound insulation, high drying speed or other characteristics.
How much mixture to take?
To answer this question, you need to take the estimated height of the screed layer in millimeters, multiply it by the area (the number of square meters in the room) and multiply all this by 1.5. Then you get the number of kilograms of screed. The fact is that with a layer height of 1 mm per square meter, 1.5 kg of mixture will be required.
This can be expressed in the following formula:
M = H * S * 1.5
M – weight (quantity) of screed, kg;
H is the height of the screed layer, mm;
S is the area of the room, sq. m
As we said above, in our case, the height will be 1 cm, i.e. 10 mm. Suppose that the area of the room is 15 square meters. m. We multiply 10 by 15 and 1.5, we get 225 kg of screed. Considering that almost all such mixtures are sold in 25 kg bags, we need to divide 225 by 25. This also applies to the Thomsit DD we have chosen as an example. Get 9 bags.
So, we have already acquired the mixture. In addition, we will need the following tools:
- a bucket of at least 20 liters;
- it is advisable to take a drill with a mixer to stir the mixture (otherwise it will turn out with lumps);
- spatulas of different lengths;
- roller – you need to take a needle.
It is also advisable to take a special extension handle for the roller, so as not to step on the poured mixture, but to level it, being at a distance.
This is what the needle roller looks like.
And here is a pen for him.
As for water, in most cases a minimum of 7 liters is required per bag. In some cases, a different dosage is indicated on the bag.
Self-leveling Concrete Floors step by step
This process begins with the preparation of the foundation. In preparation, you must do the following:
Remove all dust as possible. This can be done with a slightly wet broom;
Clog all the cracks. In this case, it is better to use high-strength cement. The most popular option is cement M500 (the letter M indicates strength, it can be from 100 to 700). In our case, this cement is perfect. In general, the letter M (in some cases, “PC”) means that a load of how many kilograms 1 cubic centimeter of cement can withstand. If it is M500, then 1 cm can withstand 500 kg of weight. Make a little cement mixture according to the instructions indicated on the bag and just pour so much of it into all the cracks that you get a flat surface;
Make dampers at the exits of the room. If there is no threshold at the exit that could hold the future screed in the room and prevent it from spilling out of the room, it is necessary to put shutters. It can be an ordinary piece of plastic or wood (only thin), which you just need to put on the output;
Primer the floor. As for the choice of primer, it is better not to make such a choice on your own. You need to come to the building materials store and say that you need a primer, for example, for a concrete floor under a screed, as in our case. The only thing you need to know is the existing foundation – concrete, sand, adhydrite, gypsum. Primer the floor with a roller – pour the primer into the bucket, soak the roller in it and simply apply it to the floor. It is important that the primer layer is uniform.
Interestingly, the technology allows the addition of a small amount of primer to the screed mixture. But the floor still needs to be primed.
Next, the process of applying a self-leveling screed begins. It consists of such stages:
Pour the entire bag of mixture into a bucket and pour water. If the whole bag does not fit in the bucket, pour as much as you can, and then pour water from the standard calculation of 7 liters per 25 kg (unless otherwise indicated on the package). For example, if you manage to fill only half, that is 12.5 kg, then you need to pour 3.5 liters of water;
Take a drill with a mixer and mix thoroughly the entire contents of the bucket. There should not be anything dry in it, there should be a liquid (very liquid, it should not be scared, it should be) a homogeneous mass. Even if it seems that the result has already been achieved, it is better to mix everything thoroughly again;
Pour the solution onto the floor. Better to start from the corner of the room;
With a spatula, we help the mixture spread evenly on the floor surface. If any tubercles have arisen, it is necessary to level the layer with the same spatula.
We take a roller with a handle and carefully run it over the entire surface of the just poured mixture. Thanks to this simple action, air will be drawn from the screed. This, in turn, will help the screed to be more durable.
We repeat the steps for creating Self-leveling Concrete Floors from the first to the fourth until the screed covers the entire floor area of the room.
When the fifth step is completed, you just have to wait until the screed is dry. In some cases, 3 days are enough to dry, in others you need to wait two weeks. Usually this information is also indicated on the bag with the mixture. And if not, experts advise you to wait 7 days.