How to make a semi-dry floor screed?

A level and strong base is essential when building or remodeling a floor. This can be accomplished, for example, by making a semi-dry floor screed. This method is easier to handle and work with during installation because it strikes a balance between the stiffness of dry mixtures and the fluidity of traditional wet screeds.

Cement, sand, and water are combined to create semi-dry screeds, which are sufficiently moist to be compacted and smoothed but dry enough to allow foot traffic to pass through them rather quickly. They are therefore perfect for places like homes and businesses where a fast-acting, level surface is required.

To attain the proper balance, the process starts with precisely measuring and combining the ingredients. To achieve the right texture, water is usually added gradually in a ratio of cement to sand. Next, ensuring that it fills in all nooks and crannies, this mixture is evenly spread over the subfloor that has been prepared.

Using instruments like a screed board or roller, the semi-dry screed is compacted after it has been laid. This is an important step because it makes sure the screed is compact and level, which reduces the need for extensive leveling afterwards. The screed is compacted and then allowed to dry and cure so that it becomes sufficiently hard to support the flooring materials that come after.

Semi-dry screeds have advantages over traditional wet screeds, including quicker drying times and a lower chance of cracking. Additionally, they are easier to handle during installation, enabling flooring projects to be finished more quickly without sacrificing durability or quality.

Anyone working on building or remodeling projects needs to know how to create a semi-dry floor screed. You can create a solid and dependable base for different kinds of flooring by using these methods and procedures, which will guarantee long-lasting outcomes and happy clients.

Features of semi-dry screed, its pros and cons

The first step in theoretical research was to attempt to define a semi-dry screed. Understandable, screed. Between the subfloor and the finishing coating is a strong, level layer. Does that explain why it’s semi-dry? Wikipedia to the rescue. My first surprise was waiting for me right here. A semi-dry screed, according to the encyclopedia, is a hybrid of a dry and a wet screed. Expanded clay makes up the bottom layer, and concrete (CPR) is the top layer. We’ve reached our destination.

An explanation or two came from articles about building sites. However, there are times when their writing makes you unsure of whether to laugh or cry. As a result, total trust does not exist. Furthermore, some forum users assert that such technology is theoretically impractical. They make reference to research on how the amount of water affects the strength of concrete. They believe that the process of cement stone formation, known scientifically as hydration, will halt midway if there is not enough moisture.

I needed to find additional resources. The outcome showed what was below. It never occurred to scientists or practitioners that CPS could turn to stone with just a tiny bit of water. However, in the former Yugoslavia, it was discovered that the nearly dry cement mixture solidifies into something akin to concrete.

Began to play around. The outcome was the development of semi-dry technology. Clarification from the knowledgeable people: semi-dry unbound cement-sand screed. It is three times less watery than "wet," which sets it apart from the classic. That’s all there is to it.

Advantages and disadvantages

I already prepared some material about two years ago, which you can view here, in which I discussed the advantages and disadvantages of semi-dry technology. The practice has required its own modifications: certain things have to be added and others removed.

TO pros are attributable to:

  • strength. A number of experts claim that it is higher than that of concrete due to the absence of cavities (voids) that remain after the evaporation of excess, unbound water. This point of view is refuted by the density of the material: it is higher in concrete. And at school they taught that the higher the density, the stronger the material. You can easily check: stand on a thick layer of foam rubber and 2-3 mm metal. What is deformed? That"s it. Therefore, such statements can be explained by advertising of semi-dry technology. However, a little less strength is enough for residential premises. An exception is a fireplace (not all types) and a stove;
  • durability. Experts talk about an operational life of 50 years or more. It has not yet been possible to test it in practice – the technology found application in the mid-90s of the last century (not even 30 years ago);
  • a smooth surface after the solution has set – obtained after grouting by machine or manually;
  • the ability to walk directly on the screed. You can walk, but only in special shoes: concrete shoes;
  • there is no risk of spilling water on neighbors below. It simply isn"t here;
  • The installation process does not leave any dirt. After the completion of the work, literally in 10 minutes the auxiliary premises were restored to their original condition;
  • high speed of work completion – the three of us, although what kind of assistant am I, in a room with an area of ​​just over 24 m2, the work was completed in about 6 hours;
  • installation can be carried out on any subfloor: concrete, rough wooden floor or soil. My doubts about the soil (as it settles, the concrete collapses) were dispelled by the foreman. Concrete is brittle, which is why it cracks under low bending loads, while cement stone has much higher bending strength. Checked in practice. I understood this in my own way: thicker, while reinforced screed, naturally more stable. Analogy with reinforced concrete floors;
  • There are no shrinkage and cracking of the surface. I agree about the shrinkage, it practically no (at least did not see it) if the solution is well protopyled (tamped), but the cracks appear in the absence of reinforcement by the fiber. The grid does not save. By the way, she has completely different tasks;
  • Compatibility with the "warm floor" – all operational characteristics allow you to do this;
  • In the leveling layer you can hide communications. No problem;
  • Repair can be continued after 72 hours – ceramic tiles and porcelain tiles are laid on glue without questions, with the rest of the flooring, you will have to wait. In some cases, laminate, up to a month.

Minuscules There exist, albeit incongruous,

  • experts unanimously say that without knowledge, experience and the presence of small-scale mechanization, laying a semi-dry screed with your own hands is extremely difficult, or rather, impossible. I wrote about this and I. I repent. From personal experience, I was convinced that if desired, everything lends itself to skillful hands and a bright head;
  • Another statement of experts: the slightest errors in the amount of water in any direction adversely affect the strength of the solution. But, what is meant by the slightest mistake? In one brigade on a bag of cement lily 17 liters of water, in another – 20. The result is the same. Along the way, I note that with a mechanized method of preparing the solution, 15 liters of water per 25 kg of cement are taken;
  • The continuity of the technological process. This applies only to a mechanized filling – you need to have time to put the solution for an hour for an hour by the room, compact and simultaneously wipe. When working manually, you can smoke, but only between the batch;
  • Hard requirements for sand – there should be a certain fraction (therefore, river is not suitable) without clay and stones.

Types of half -dry screed

When I began learning about the various varieties of semi-dry screed, I was in for another surprise. I counted more than a dozen possibilities, and it turned out that the writers’ fantasies are insane. Actually, there are three:

  1. bound – this is when a semi-dry mortar is poured directly onto the floor slab and adheres to it;
  2. floating – the formed cement stone has no direct contact with either the ceiling or the walls. At the bottom there is foam plastic (insulation) or soundproofing material, and a damper tape is attached to the walls;
  3. on the separating layer – something intermediate between the first and second types: with overlapping contact there is no – a thin polyethylene film (waterproofing) is laid, and damper tape is placed on the walls. In passing, we note that when laying rolled waterproofing with a thickness of more than 1 mm, the screed is already floating.

It’s a theory, though. For practical purposes, the classification makes no difference, though many experts contend that reinforcement of the bound screed is unnecessary. I noticed a minor variation: in order to prevent the concrete base from sucking out the last of the water in the solution, it must be carefully primed.

I could not discern any distinction between a separating layer and a floating screed. Semi-dry floor screed technology is one to one in both situations.

Materials and tools

I discovered the third surprise when I looked into the requirements for supplies and equipment. A trowel and a concrete mixer are mentioned in almost every article concerning semi-dry screed. I foolishly thought that groups performing manual labor rented these devices. Imagine my astonishment when I arrived at the location and observed:

  • several bags of M500 cement;
  • a ​​pile of sand;
  • a large sieve;
  • several packages of fiber;
  • polyethylene film;
  • a stack of metal reinforcing mesh;
  • a screwdriver with an incomprehensible hook;
  • a substrate for laminate;
  • a construction gun with hot glue;
  • a twist of copper wire;
  • a laser level;

A repair tool that, even in the absence of specific training or expertise, enables you to screed a floor precisely and without additional effort. It makes figuring out the minimum screed layer, marking beacon installation locations, and forming a plane with self-tapping screws simple. R-DISTRIBUTION LLC, Advertising; ERID: LjN8Juyiz.

  • rule;
  • roulette;
  • construction pencil;
  • bucket;
  • plastic cup;
  • two plaster floats;
  • shovel;
  • several metal pipes about 3 meters long;
  • metal hook about 1.5 m long;
  • construction knife;
  • two pairs of concrete shoes.

No trowels or concrete mixers.

Some tools and devices were surprisingly present. Their function in the technological process eluded me. I asked the builders a ton of questions even as I changed into my work clothes. I got thorough responses.

Cement. It needs to be in a semi-dry mixture of the M500 brand in order to obtain a solid base. M400 as a last resort, but only for a maximum of two months. Not a single M300 brand. I knew that the grade of Portland cement decreases by 100 units every six months in a warehouse, so why was the foreman so concerned about shelf life? Was M500, sat for half a year, then changed to M400.

Sand. Quarry sand is required; however, its fineness modulus can reach up to 2.5 units. To be clear, this sand needs to be sifted through a sieve with a hole diameter of 25 mm in the first place, and then 14 mm in the second place, per GOST guidelines. Everything that needs to be used but did not make it through the previous sieve. Clay should not be present in the sand; in fact, it is permitted, but only in small amounts (no more than 3% of fine clay inclusions); accidental plant debris is excluded entirely. Since it’s natural, any humidity will do.

For information, the teams used a fine sieve to sift the sand only once, seemingly at their agreement. While mixing, large pebbles fell off the cement mound. They were taking them out all the time. Although it is faster, the caliber of the work is unaffected.

Fiber-fiber. Rather than stopping cracks from appearing on the surface, the reinforcing mesh stops them from growing. In order to guarantee the integrity of the surface, polypropylene fiber is added to the mixture.

Screwdriver. When tying the reinforcing mesh, the hook that is placed into the cartridge makes it possible to quickly twist the copper wire. Despite being told that this approach has been around for a while, this is the first time I’ve come across it.

Pipes. utilized as illuminators. When driven into a solution that has already been laid, only they do not deform.

Dig a shovel. Shovels come in various varieties. The word "shuffle" comes from the necessity of a scoop, also referred to as a shufel.

Use substrate in place of damper tape. After cutting it into strips, fasten it to the wall. Much less expensive.

Hook. It is advised by SNiP to place the reinforcing mesh on the screed layer and then add a second layer on top of it. The team uses a different method; they lay a mesh on the floor’s base, cover it with a bucket of mortar, and then use a hook to raise it slightly so that it is inside the lower portion of the screed. Easy and quick. A lovely fix for an issue with technology.

Adhere the sliced backing to the wall using hot melt adhesive.

Pour water into the mixture in the cup, or rather, onto the cement and sand mound.

Metal mesh needs copper wire to be tied.

Polyethylene film: the screed is covered with it after the solution has been prepared on it.

The remaining tools serve a purpose that is obvious.

Calculation of material requirements

The following formula is used to determine how much material is needed: the thickness of the screed multiplied by the square meters of the room’s area. The fill volume in m3 is the result of this. Next, multiply the amount of cement per 1 m 3 of mortar grades M150 and M200 by the volume shown in the table. After rounding up, we divide the results by the weight of the material in the package to get the total number of bags of sand and cement.

Table 1 shows the amount of sand and cement used per 1 m 3 of solution.

Cement brand Material consumption per 1 m3 of solution
Solution grade M150 Solution brand M200
Cement, kg Sand, kg Cement, kg Sand, kg
M400 Z90 1310 490 1350
M500 370 1350 410 1400

Preparatory work

Professional builders who use a mechanized method to install dry screed follow a slightly different procedure step-by-step than when they worked in teams without small-scale mechanization equipment. It is not worthwhile to replicate each one of them in its entirety. Everybody has their own methods for completing specific tasks that significantly streamline the process as a whole. I therefore combined the best elements from each to create one. Consequently, the following is how semi-dry screed technology is designed:

  • preparatory work – includes foundation repair, waterproofing and insulation;
  • gluing damper tape;
  • finding the screed line;
  • laying reinforcing mesh;
  • preparing the solution;
  • installation of beacons;
  • laying the screed;
  • care of the surface of the solution.

I apologize for repeating myself, but the floor’s base needs to be sturdy. It might be:

  • rough floor made of unedged boards with minimal gaps on wooden joists or on 2-T metal beams (“Stalinist” houses, cottages with lightweight ceilings);
  • well-compacted soil with bedding (sand or expanded clay) in the basements and first floors of private houses;
  • any monolithic ceiling.

The most complicated technology is a floating screed, which is used to explain it. A reinforced concrete floor will receive the pour. Venting is required when pouring onto a wooden floor. If not, everything will degrade and break down. But that’s a topic for another day.

The work surface must be thoroughly cleaned before beginning any preparatory work. The base is swept, tools are moved to another room, construction waste is collected in bags, and—even better—a construction vacuum cleaner is used in place of a broom.

When there are cracks, chips, or pits in the slabs’ surface, traditional TsPR or the least expensive tile adhesive is used to seal them. The same process is also applied to cracked seams. Although using specialized repair solutions is more costly, the outcome is the same. A surface that is relatively even, even to the naked eye, is what matters most in this process (small waves do not get in the way of creating a screed). Reaching the point of fanaticism is not worth it. Either way, all the flaws will be concealed by the leveling layer.

It would be redundant to go into further detail about the technology used to get the subfloor ready for screeding. On the website, there is a different article. This link will direct you to it.

Once more, everything is meticulously swept.

The base is essentially prepared to lay the screed in this form. However there are some crucial details:

  1. 1. Concrete, like a pump, will pull out the small amount of water from the semi-dry screed composition, as a result of which the bottom will turn into small granules, unrelated to each other. It is also not possible to simply wet the surface to saturate the ceiling with moisture – the water ratio of the screed components will be disrupted. How the hydration process will go in this case, no one can predict. Therefore, the waterproofing of the ceiling is needed or repeatedly treated with a primer of deep penetration. You can also "concrete contact", but this is an expensive pleasure.
  2. A semi -dry screed has an unusual property: it itself is good for noise. But laid directly on reinforced concrete, on the contrary, the noise enhances. Therefore, we need a layer of noise -insulating material, unless of course the owners of the apartment do not want to put their family life for public display. Sorry, listening. It will help to solve the problem of insulation with soundproofing properties, for example, the basalt wool "Rockwool" TF-BOARD. You can use polystyrene foam (foamed PSB-S-35 or, which is better than PSB-S 50; extruded brand 35)-it extinguishes shock noises well, but not in combination with laminate.

A brief observation: a floating screed as a result.

To be clear, if insulation or soundproofing material is installed, waterproofing is typically not done in living rooms (living room, children’s room, and bedroom) in apartments, starting from the second floor and up. "You can’t spoil the porridge with oil," people say. The site team advises that the waterproofing be done there and in any case. God forbid there be flooding or water leaking out of the kitchen or bathroom.

One brigade used bitumen mastic to create waterproofing and placed it over the slab of basalt wool; the other brigade used rolled materials (using Technonikol’s "Uniflex EPP" elastic rolled material), and PSB-35 foam was chosen to act as a noise and a heater. It’s interesting to note that this brigade has spied on something: using rollers is advised when using roller materials. Instead of rolling, the workers made a complete impression on the ground. Adhesion with the base is much better, but it takes a little longer.

Every choice has advantages and disadvantages. Links to articles explaining what to choose and how to complete tasks will be helpful.

  • “Waterproofing of the floor before screed”;
  • “How and how to waterproof a bathroom floor?";
  • “Which insulation is better to choose for the floor?».

If the preparations are done correctly, the cake should look something like this (see photo):

Clearing and restoring the reinforced concrete floor is step one; bitumen primer for roll waterproofing is step two; rolled waterproofing material is step three; insulation is step four; and reinforcing mesh is step five.

This tutorial explains how to make a semi-dry floor screed, which is an essential step in building and remodeling projects. Prior to installing flooring, semi-dry screed provides a well-balanced combination of strength and workability, making it perfect for uneven surfaces. We’ll go over the supplies required, how to mix and apply them step-by-step, and important advice for leaving a smooth, long-lasting finish. Gaining proficiency in this method will improve the caliber and durability of your flooring, regardless of your level of experience with do-it-yourself projects.

Step-by-step instruction

Finally, we arrived at the most crucial component: detailed instructions for installing semi-dry floor screed.

First step: damper tape. Both teams opted to purchase a foam laminate backing rather than an already-made damper tape, as the latter is somewhat pricey. It was 10 mm thick Izolon in both instances. The strips took a few minutes to make. They can be easily trimmed because they were cut slightly wider than the future screed. They were bonded using hot glue in the second instance and liquid nails in the first.

An improvised damper serves multiple purposes simultaneously:

  • blocks the absorption of moisture from the solution by the wall;
  • prevents the screed from meeting the wall when the concrete begins to “become naughty” under the influence of temperature changes;
  • protects against the formation of cold bridges between the wall and the screed;
  • serves as a barrier to sound waves traveling both in the thickness of the walls (structural noise) and in the screed itself (indoor sounds).

Step 2: Identifying the knot. Drawing a line of beacons on a wall is accomplished using the following algorithm, according to the classics: First, the wall is painted with an horizon line. It assists in locating the highest point at the floor’s base. The minimum screed thickness of 4 cm and the insulation thickness, if installed, are added to this. This is the path that the beacons are positioned along.

The crews did not behave "according to the rules" in either scenario. This method has the right to life in general. They immediately located the highest point close to the insulation by using a laser level. It was elevated from the screed line by 3.8 centimeters. The insulation’s tendency to shrink under the weight of the solution and somewhat even out height variations served as the impetus for this. Thus, such numbers and technology. However, you will need to use the classics—which are explained in detail here—when working with a tied screed.

I was also intrigued by the way they utilized foam to cover up two depressions, which the foreman referred to as "blockages." The depressions were approximately 1 m2 in size and 7 mm deep. They used a thermal cutter to cut polystyrene foam patches of the same size, which they then slipped under the insulation.

Step 3: The mesh reinforcement is laid. Different technologies were employed by the teams. I mean a more straightforward one; this is ideal for do-it-yourself artisans.

Over the insulation, a mesh with 100×100 cells and 1.5 mm wire thickness was placed, overlapping by roughly 10 cm and spaced 2-3 cm from the walls. After removing the insulation from a standard telephone cable, the copper wire was used along with a screwdriver. I was unfamiliar with the technology at first. The overlapping mesh’s cell corners were wire-wrapped two or three times. The top was then knotted after that. Simple to perform without pliers by hand. We created a loop by inserting a screwdriver hook into it. Once the tool is turned on, you’re done. flawless twisting and tightening of the wire at the same time.

The entire task took a maximum of thirty minutes. Of course, I’ll take note.

Step 4: Get the solution ready. I was a little surprised, again, by the same team that had tied the reinforcing mesh together with a screwdriver. I was aware that film could be sealed with a wet solution. I’ve personally done this a few times. However, I had no idea that a semi-dry screed composition could be made in this manner. Maybe the stories about how difficult and time-consuming it was to prepare the solution confused me. Perhaps. However, I wasn’t ready for what I witnessed. I’ll walk you through every step of performing such an operation:

  • the film is spread;
  • one worker throws sand onto a sieve;
  • after a decent amount of sifted sand has formed there, he throws it into a pile on the film with a second shovel. Exactly 30 full shovels;
  • levels the top of the pile, forming a small plateau;
  • throws a bag of cement onto the plateau, breaks through the packaging with a shovel and pours out the contents;

  • again throws 30 shovels of sand;
  • and another bag of cement for the pile;
  • after that the pile is shoveled twice. Doesn’t keep track of where to get each shovel from. Fiber is added to the second pile. The team believes that it is more difficult to add it with water, but you can slowly add it to the growing mound without any problems.

It surprised me that the mixture blended well after two transfers. Not in the greatest way, perhaps, but sufficient to carry on working. 17 liters of water were then measured after that. The procedure carried on:

  • they began to form a new pile and after each throw with a shovel they poured a plastic glass of water onto the top of the mound;

  • let it sit for about 10 minutes;
  • After this, the solution was transferred into two shovels from place to place twice more. And that"s all. The solution is ready for installation.

Additionally, the foreman made sure it was ready by forming it into a ball with his hands. There was no leakage of water. The ball remained intact. The group deemed the solution to be operational.

Consequently, the component proportion was:

  • sand – 60 shuffle shovels;
  • cement – 2 bags of 25 kg if you throw sand quickly, and 2 bags of 50 kg with sand on each shovel with a slide;
  • water – 34 l.

For the same amount of dry mixture, the opposing team has 40 liters of water, which is more. A small amount of water leaked from the compacted mass. Consequently, it appears that both arguments—that is, the lump should be wet or dry—are correct. The batch has enough screed thickness (4 cm) for approximately 5 m2.

Installation of beacons is step five. The teams’ methods for placing beacons are diametrically opposed. One inserted multiple screws into the floor’s base using a wrench head. These beacons first need to be grouted with skill. Using this technology to level the surface is very challenging without experience. Second, they compromise the waterproofing layer’s integrity. The group, however, found a simple solution to the second issue: after the job was completed, they removed the beacons, poured a small amount of liquid bitumen into each hole, and sealed it with a solution.

They gave a straightforward explanation for their beacon selection: a metal pipe on foam plays. That’s the reason they gave it up.

In contrast, the second team employed a pipe. They did this by pouring pathways along the beacon’s lines that were 10–15 cm high and 20–30 cm wide. Using a hook, they raised the reinforcing mesh (which is raised each time the solution is poured straight onto the insulation). They effectively subdued it. They pressed the pipe into the compacted solution after placing it on top. A laser level was used to regulate the horizontal. In this instance, the pipe was installed two to three meters rather than the full length of the space.

Step 6: Mortar is laid. They poured mortar between the pipes and trampled it down after installing the beacons. The extra was chopped off. They started to float the solution after spreading it evenly across the floor. Here are two points.

  • You can walk in simple shoes, but then difficulties arise with grouting – you have to spend additional effort and time to remove the marks left behind. That"s why concrete shoes are needed.
  • The solution is alkaline. Therefore, gloves are required on your hands. T. To. some workers do the grouting while kneeling; knee pads are needed – you can burn the skin on your legs.

Important: porcelain and tile do not require grout. The maximum height difference allowed by the rule is 1 mm.

Let us highlight a significant benefit of trampling: poor compaction occurs when a trowel is used in the corners of walls and the joints between the floor and the walls, which may eventually affect the floor’s performance characteristics. Other than the space between the wall and the heating pipes, there are no areas that are inaccessible for feet. However, the laborers discovered a hammer here as well.

You can see how much water is in the solution while grouting. In the event that there is excess, it will stick out under the grater and prevent the final operation. A deficit prevents the formation of an even crust. It is therefore advised to pour a bucket of solution onto the floor, stamp it down, and attempt to rub it in after the solution has been prepared. If you added too much water, make the necessary corrections by adding more sand and cement if the mixture is too wet, or water if it’s too dry. However, since the solution only takes an hour or so, everything must be done quickly.

7. Take care of the surface. The beacons are taken out once they have been laid and grouted. Traces are sealed using the adhesive. In our instance, the pipes were taken out during the grouting and screeding process, and the screws were taken out once everything was finished. They were taken out and used elsewhere as soon as they were no longer needed.

Who knows what will happen after that? In areas where water was slightly visible, one team deemed the job done and suggested the owners start additional work (tiling) in three days.

After stopping the air flow to the CPR and covering the screed with film the following day, the second one allowed it to dry for 28 days. The watering can was used at a rate of 0.5 l/m2. The owners then have to take care of the screed by giving it a spray bottle full of water (the same amount of moisture as the first time). The second and third days are when this needs to be completed. I was unable to comprehend the reason behind this and was not provided with any satisfactory explanations.

I was unsure of which was correct when I answered. As a result, we ran an experiment with the site team: we used both technologies to prepare a bucket of solution, which we then filled into 50×50 cm squares with a 4.5 cm thickness. One was left open where the water was deeper. Three cells each received the drier one. Two were covered with film, one was left open, and one received two days’ worth of watering. They checked the strength a month later.

A high moisture content slab shrank by 1-2 mm while remaining difficult to break with a hammer. Water-filled solution beneath the film comes in second in terms of strength. After all, the water evaporated early and the hydration process was unable to finish, so tiles without film finished the list. However, all specimens are strong enough to be used as screeds for loads carried by pedestrians. The top two choices are strong enough to support large furniture and a full bathtub. The final two are improbable. I’m not positive. However, I wouldn’t take a chance on it.

I hope my experiment provoked thought in curious do-it-yourselfers. Yes, I did forget to mention that on the second day, an expansion joint 3 mm wide and 1/3 of the thickness deep is cut in the middle of the screed in rooms larger than 25–27 m2. Well, that appears to be it. didn’t overlook anything.

Private questions

Numerous questions with contradictory answers can be found on the forums. I’ll use my expertise to respond to a few of them.

How much time does it take for 7 cm of semi-dry screed to dry? Regular CPR and semi-dry screed dry according to slightly different guidelines. In the latter, the time it takes to reach full strength increases as the poured layer gets thicker. The standard for a semi-dry mortar is that it takes approximately 10 days, and at most 28–30 days, to reach 70% strength.

Thickness at minimum and maximum. 4 cm is the minimum thickness. If the layer is thinner, the water will evaporate more quickly than the solution gets stronger. A maximum is constrained by the subsequent factors:

  • weight – must withstand the ceiling;
  • speed of pouring – the entire thickness must be laid and compacted in several layers within one day;
  • financial capabilities of the owners – a screed thicker than 7-8 cm is ruinous.

Actually, a maximum thickness of 10–15 cm is allowed. Seven cm is the most typical.

Does it need to be reiterated? The floating screed’s mesh needs to be. Fiber fiber: not required. A "helicopter" (an iron coating of the surface with cement dust) may be used as a last resort.

When is a semi-dry screed not appropriate? Semi-dry screeds are not appropriate for weak floors because of their high specific gravity.

How much time does it take to dry? Gaining maximum strength takes 28–30 days. However, you can begin working far earlier:

  • walk after 12 hours;
  • lay the tiles after 3 days;
  • lay linoleum every other week;
  • laminate and parquet work in a month. Previously not possible due to high humidity of the screed.

Regular or semi-dry screed. Both "wet" and semi-dry screeds have advantages and disadvantages of their own. It is hard to favor one approach over another. We were unable to provide a definitive response even after conducting a comparative analysis, which is available to view here. Only suggestions are made.

Materials Needed: Cement, sand, water, plasticizer (optional)
Steps: Mix cement and sand thoroughly. Add water gradually while mixing until you get a damp, crumbly consistency. Spread the mixture evenly across the floor and compact it using a screed board. Allow it to dry for several days, keeping it moist to aid curing. Once dry, the semi-dry screed should be firm and ready for further finishing.

In construction projects, creating a semi-dry floor screed is a useful and effective method of achieving a level surface for flooring. Compared to conventional wet screeding techniques, you can create a mix that is easier to handle and spread by precisely balancing the amounts of cement, sand, and water.

One of the main benefits of semi-dry screeding is that, depending on the particular needs of the flooring, it can be laid to a precise thickness of between 50 and 70 mm. This thickness minimizes downtime in your project by ensuring structural integrity and facilitating rapid drying and setting.

Achieving the proper moisture balance is essential when preparing the mixture. If the screed is too wet, it becomes difficult to work with and may cause shrinkage cracks as it dries; if it is too dry, it won’t bind properly. To ensure that the mixture is cohesive but manageable, it should crumble when disturbed but clump together when squeezed.

When applying, evenly distribute the mixture over the floor using a straightedge or screed board. Proceed carefully, making sure that the thickness and level are maintained all the way from one end to the other. This procedure enables prompt adjustments, guaranteeing that any irregularity is rectified prior to the screed solidifying.

Compared to wet screeds, semi-dry screeds require less curing time after installation; they are usually ready for foot traffic in 24 to 48 hours. However, depending on the environment and the thickness of the screed, complete drying and curing may take longer. This technique not only expedites the building process but also offers a solid and trustworthy foundation for the flooring materials that come after.

In summary, using a semi-dry floor screed provides a workable way to achieve a level and long-lasting floor surface in building projects. Many builders and renovators prefer it because you can ensure efficient installation and minimal downtime by perfecting the mix consistency and application techniques.

Video on the topic

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Fedor Pavlov

Interior designer, author of books on residential design. I will help you make your home not only functional, but also beautiful.

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