Advantages and disadvantages of semi-dry floor screed

A popular option for building and renovation projects, semi-dry floor screed offers a special combination of benefits and considerations. Sand, cement, and water-reducing agents are combined in a drier mixture to create semi-dry screeds, as opposed to traditional wet screeds, which are more fluid and need longer drying times. Compared to wet screeds, this composition allows for quicker setting times, which frequently allows for a faster transition to the following stages of construction.

The quick drying time of semi-dry floor screed is one of its main advantages. This feature is especially helpful for projects where time is of the essence, like renovations or spaces that require flooring installation right away. Semi-dry screeds’ lower moisture content quickens the drying process, enabling later trades to start construction earlier and possibly cutting down on project completion times.

Semi-dry screeds also have the benefit of strength and durability. The final product is denser due to the lower water content, which improves load-bearing capacity and lessens the chance of cracking. Semi-dry screeds are appropriate for a range of applications, including commercial spaces and residential flooring, where a high degree of durability is required due to their structural robustness.

However, if you decide to use semi-dry floor screed, you should be aware of some disadvantages. The exact mix and installation requirements are one important factor to take into account. For optimum performance, it is imperative that the proper compaction and moisture content are achieved during installation. Application requires careful attention to avoid problems like shrinkage cracks and uneven surfaces caused by improper mixing or installation.

Semi-dry screeds can also be more expensive initially than traditional wet screeds because they require specific materials and installation knowledge that is necessary for a proper installation. In many building and renovation scenarios, it is the preferred option due to its higher initial investment, which is often justified by the potential time savings and long-term durability benefits.

Advantages Disadvantages
1. Faster drying time compared to traditional screed. 1. Requires careful mixing to achieve correct consistency.
2. Suitable for underfloor heating systems. 2. Can be more expensive than traditional wet screed.
3. Reduced risk of cracking due to lower water content. 3. Limited to certain thicknesses, typically up to 50mm.

Types of screeds

Three types of screeds are used by builders to lay floors:

  1. Dry. Made from bulk materials. After leveling, slabs of plywood, fiberboard or gypsum fiber board (gypsum fiber sheet) are laid on it, on which the floor covering is mounted;
  2. Semi-dry. This name is determined by the amount of water in the solution – 1/3 part. The mixture includes cement, quarry sand, fiber fiber and plasticizers (introduced into that part of the solution that is placed in hard-to-reach places);
  3. Wet. It is based on a liquid (ordinary) cement-sand mortar.

In the construction industry, semi-dry screed is actively replacing other technologies due to the development of efficient plasticizers and reinforcing fiber.

Characteristics of semi-dry screed

It is situated halfway between traditional wet screeds and dry screeds. used to cover up communication pipes and remove subfloor flaws. Its qualities enable you to address issues with heat, sound, and room waterproofing.

Applied to the installation:

  • linoleum;
  • tiles;
  • parquet;
  • laminate;
  • carpet.

When mineral wool, plain, or extruded polystyrene foam is placed as insulation between the mortar and the floor base, it can be laid rigidly or floating.

Semi-dry screed provides a compromise between conventional wet screed and dry screed systems in the flooring industry. Faster drying times are a major benefit as they enable quicker progress with later construction stages. Furthermore, compared to wet screed, semi-dry screed has less chance of shrinking and cracking, which makes it perfect for underfloor heating systems. To achieve the best strength, it can be more expensive than using traditional methods and needs careful control over the moisture content during installation. When choosing floor screed solutions, homeowners and builders can make more informed decisions if they are aware of these benefits and drawbacks.

pros

There are numerous benefits to using semi-dry mixtures for floor screeding. Nonetheless, there are fundamental and secondary ones among them.

The semi-dry screed’s primary benefits are:

  • The smooth surface of the screed allows you to lay tiles, parquet, laminate, etc. without additional work and, therefore, costs.d.
  • Possibility of installing water and electric heated floors.
  • Strength. It is achieved in two ways: through the hydration process, resulting in the formation of cement stone without cracks and cavities (cavities); inclusion in the components of a mixture of small reinforcing fibers (fiber fiber) from steel, basalt or polymers.
  • Budget cost. It is formed from a relatively low cost of consumables and low labor costs (performed very quickly, but by a team). This allows you to hire professionals for installation without exceeding the overall costs compared to wet screeding yourself.
  • Ability to work without flooring when laying the screed itself and carry out other finishing work indoors 12 hours after grouting the surface.
  • Work can be carried out in any weather conditions. The allowed range of air temperature fluctuations is from -5 below zero to +40 degrees above zero, humidity – from 60 to 90%. Such fluctuations do not affect the quality of work.

It’s important to remember that building strength takes 28 days. Consequently, it is not advisable to place materials, tools, or equipment with a high specific pressure per unit area on the screed during this time. In the event that such a necessity did arise, slabs made of plywood, fiberboard, chipboard, or wide boards must be placed beneath the weight.

Simultaneously, there exist several other benefits that are often overlooked by consumers:

  • due to the porous structure of the cement stone, the screed cushion serves as an additional layer of heat and sound insulation;
  • the properties of the set solution eliminate moisture leakage, which allows you to avoid waterproofing (with the exception of a warm water floor);
  • the ability to lay on various floor substrates, including concrete, wooden subfloor, soil;
  • ability to withstand large mechanical loads, including dynamic ones (various types of impacts);
  • there is no risk of water leaking onto the lower floor, which is possible with wet screed;
  • it becomes possible to hide communications (various pipes and cables) inside the laid pillow;
  • can be used in hard-to-reach places and on inclined surfaces;
  • environmental safety – all components of the mixture are made from natural materials, which guarantees the absence of allergic reactions of family members to the screed;
  • relatively clean process, without traces of mortar on the walls;
  • minimum setting time when laying porcelain stoneware and ceramic floor tiles – 72 hours, linoleum – 7-8 days;
  • high speed of work – the use of low-mechanization equipment reduces the time of laying the screed several times, reducing the cost of work.

Be aware that other flooring types must strengthen for at least 28 days, and ideally for 40 days, before being installed on a semi-dry screed.

Utilizing contemporary materials in the mixture’s component parts, especially reinforcing fibers, allowed for the reduction of the solution’s weight as well as the first two goals of strengthening the screed layer to a 4 cm thickness and decreasing the layer’s strength. The combined effect was a sharp reduction in the load on the floor slabs. This is yet another significant benefit of semi-dry screed.

Disadvantages

Each medal has an opposite side. There are drawbacks to the arrangement of this kind of screed, albeit they are fairly substantial.

Semi-dry floor screed drawbacks:

1. Technology laying places a high demand on employees’ knowledge and abilities. It is not possible for those who are building or remodeling an apartment (or house) by hand. Why? The following are the causes:

  • Low fluidity of the solution, which does not allow achieving the desired consistency of the mixture when mixing manually. You will need special equipment – a pneumatic damper.
  • Sensitivity of the solution components to the amount of water:
  1. Excess moisture. For some reason, inexperienced builders always try to add it when the solution is poorly mixed. However, excess water leads to the formation of a network of small cracks. Under dynamic loads, simple walking of an adult, cracks expand and go deeper. The screed is deformed, the floor requires new repairs;
  2. Lack of water does not allow the hydration process to bind all cement particles. No complete hydration of cement – no density of the screed. Result – it begins to crumble.

Advice: A basic concrete mixer will do a good job of mixing the solution for small areas of laying.

  • Continuity of the process. It is impossible to make a high-quality screed alone or in pairs. The process of setting the components of the solution occurs very quickly, which requires simultaneous work: on preparing the mixture; laying it on the base of the floor; compacting the screed using low-mechanization tools.
  • Looseness of the solution. The low density of the mixture requires, a priori, the use of special equipment for compacting the semi-dry layer of the screed. This operation is performed by a trowel (smoothing) machine.

The equipment on the above list is not used by people who lay floors by hand. You can hire (rent) it. However, this operation needs to be done by professionals due to the inexperience working on it.

2. A decrease in the apartment’s usable volume, which is particularly apparent in rooms with low ceilings. The thickness of the ligament is correlated with volumetric "eating." It should be at least 4 cm under a normal floor and at least 5 cm under a heated floor.

3. Only quarry sand is utilized; river sand is not. To get rid of clay impurities, it must be purchased, sorted, and then thoroughly cleaned. The cost of ready-made sand is high, so not everyone can afford to purchase it.

4. Because the mixture’s components are mixed in different proportions during the grouting and cement stone formation process, the thickness of the screed layer is formed differently, making precise material calculations impossible.

5. Compaction of the mixture in corners and close to walls is difficult. resolved by tamping by hand and incorporating plasticizers into the mixture to improve its fluidity.

Nearly all of the drawbacks are associated with the work’s performers. When semi-dry floor screed is applied by professionals, the flaws are invisible. When compared to other types of screeds, the lower cost of materials offsets the increase in work associated with paying hired labor.

Conclusion

All base types have semi-dry screed installed to improve the room’s hydro, sound, and heat insulation. Among the principal benefits are:

  • high strength;
  • low cost of materials, covering the cost of hiring a team of professionals;
  • a convenient opportunity to hide communications under the floor;
  • Possibility of installing heated floors.

The following are the main ways that disadvantages arise when working independently:

  • you need special equipment for stirring the solution and compacting the laid mixture (trowel);
  • difficulties in determining the proportions of water and dry solution;
  • the minimum number of people for simultaneous work is 3.

Furthermore, it ought to be mentioned that dry screed:

  • steals the height of the room;
  • difficult to fit in corners, behind pipes and radiators.

In a nutshell: hiring professionals is a great way to get expertise in a warm field, but it can also steal the room’s volume.

Semi-dry floor screeds are a good choice for a variety of flooring projects because they have a mix of advantages and disadvantages. A primary benefit is the reduced drying time in comparison to conventional wet screeds. As a result, flooring materials can be installed more quickly, cutting down on project completion times. The semi-dry mix also produces a smoother, more even surface because it is easier to work with and can be leveled more precisely.

A further advantage is the decreased chance of cracking. Because there is less water in the semi-dry mixture, shrinkage and the chance of cracks forming when the screed dries are reduced. This may result in a floor that is more resilient and long-lasting. Additionally, the procedure usually results in less mess and less water that needs to be managed on-site.

There are a few drawbacks to take into account, though. To get the best results, semi-dry screeds can be more labor-intensive to mix and apply, requiring skilled workers. The equipment required, such as specialty pumps and mixers, may also drive up project costs. Furthermore, while the lower water content helps shield the screed from shrinkage cracks, it can also lessen its flexibility, which could cause problems in places where heavy loads or movements are common.

To sum up, semi-dry floor screeds provide quicker drying times, lower chances of cracking, and a cleaner application, making them an excellent option for a variety of building and remodeling projects. Nevertheless, they do need specialized tools and labor, which raises the total cost. Having a thorough understanding of the benefits and drawbacks will enable you to make an informed choice that best meets the unique requirements of your flooring project.

Video on the topic

Advantages and disadvantages of semi-dry floor screed

Mechanized semi-dry screed – all the pros and cons

part 2. THE WHOLE TRUTH ABOUT SEMI-DRY SCREED

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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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