Screed screed - all information in this manual
- Why sand screed "> 1. Abrading old screed
- 2. Abrading of new screed
- Freshly polished screed is sensitive
The screed is the connecting layer between the raw construction floor and the floor covering. Floor coverings are usually very thin layers of high-quality and sensitive materials, which can not take over a balancing task. They have to look good, be abrasion resistant and easy to clean. Crests and holes in the ground penetrate through the floor covering. This prevents a smooth screed.
Why screed screed?
The porous surface of the screed is always somewhat uneven due to the aggregate used and its grain size. But if the screed is sanded, you get a surface with defined properties. Dome and holes are leveled out and a uniform roughness is created. If the screed itself is supposed to be the visible floor, sanding and polishing is the best prerequisite for applying the seal. This is indispensable due to the absorbency of the dried screed.
There are two indications why a screed needs to be sanded.
1. Abrading old scraps
Old screed is screed that has been installed for several years and provided with a covering. If carpet or PVC was used, it was adhered to the entire surface. Remains of adhesive remain when removing or parts are torn out of the screed. After removal of the floor covering remains an uneven surface left, which only needs to be prepared for the new surface, so filled and / or sanded.
2. Abrading of new screed
If a new floating screed was installed, the result is obviously smooth and the same everywhere. But on closer inspection, one quickly realizes that more or less large cavities have formed. These must be compensated before the order of the floor covering. New screed is particularly easy to grind, as it is still a bit softer than screed, which had time to harden for years.
It may also be that the height of the screed has been calculated incorrectly and the final result is too high. Here a sanding of the fresh screed can be a quick and clean correction. Since liquid screed must be sanded anyway, falls in spite of the obvious Baufehler no additional work. It was just consumed a little too much material, but this is negligible given the low prices (2.50 per 25 kg sack of cement screed / 8 € per 40 kg sack calcium sulfate screed).
If a screed was installed in a humidified pouring and stripping technique, sanding is usually no longer necessary. The process of this procedure provides for a permanent rubbing and after-smoothing of the screed already during installation. In this case, a cut is only indicated if the surface for the floor covering has to be roughened. This may be the case with carpet or PVC adhesive methods.
Industrial floors can be improved by grinding the screed in their technical properties. For this purpose, usually a screed with a coarse grain is used as a supplement. If this is exposed by professional sanding, you get a very hard and durable surface. With a polish, this surface is also visually very appealing. If you omit the polish, you get a surface with good anti-slip properties.
It is recommended to sand screed only by machine. To grind a room by hand is very tedious and not recommended for reasons of health protection. Professional grinding machines for soil preparation are very cheap to rent in tool rental. As an indicative price you can calculate about 25 euros per day for renting a screed grinding machine. Since working with a screed grinding machine is very fast, these costs are easily calculable. An apartment of 100 m² is completely sanded off on a 7.5-hour day. Since the machine works with a single-disc plate, some manual labor is needed in the corners.
A single-disc screed grinding machine sucks the loose material during the grinding process. Nevertheless, after sanding, the entire room must be thoroughly exhausted again. When applying adhesives or leveling compounds, there must be no loose residue left on the screed layer. Cleaning is part of sanding screed.
Freshly polished screed is sensitive
When rubbing and curing screed, the upper pores of the cover layer close with cement or gypsum slurry. A certain porosity remains but preserved. With a ground screed, however, the potted pores are fully opened again. In this condition screed is particularly sensitive to contamination. For the application of adhesive or a filler layer of the most open porous condition is advantageous because the screed is so particularly absorbent. If the screed but not provided with a cover layer, the open-pored state is problematic. When installing in garages or workshops or storage rooms, the sanded screed must therefore be sealed as soon as possible. For this purpose, a synthetic resin is usually used today.
Seal sanded screed
The application of a synthetic resin sealant should not be confused with the installation of a synthetic resin screed. The installation of synthetic screed is reserved only for specialized companies that are certified for the installation of this material.
A synthetic resin seal is a thin layer of one to two millimeters, which provides lasting protection against ingress of liquid. Their installation is very simple: The synthetic resin is mixed according to instructions and distributed with a squeegee. The liquid flows evenly into one another and thus forms an absolutely uniform layer. A two-component set screed seal costs about 100 euros in a 5-liter bucket and is enough for about 25 m². The trade also offers epoxy resins for floor coverings, which achieve very appealing effects with colors and flakes.
Tips for quick readers
- Always screed the screed for gluing saw
- Seal screed without cover immediately after sanding
- Ground screed is very absorbent
- Always work clean
- Working with a rented screed grinding machine saves time, money and effort