Improve Tile Design

[Dave]

Improve Tile Design

Technology Makes Substrate Movement Joints Obsolete

Architects, specifiers and end-user consumers often attempt to dissuade tiling contractors from putting movement joints in the correct places in tiled flooring, because they say it detracts from the visual appeal of the overall installation. In many cases there can be some leeway as to the precise positioning of surface movement joints. However, there is no leeway at all where there are also movement joints in the substrate.
But, Schlüter-BEKOTEC eiminates the need for movement joints in the screed, which gives greater flexibility in surface tile design.
Surface covering movement joints must be placed directly over any existing movement joints in the substrate. We're often asked if surface joints can be offset by putting them just a small distance away, but this is rarely possible.
On many occasions we've seen designs where contractors have offset the movement joint in the surface only by millimetres from the one in the screed, and the ceramic tile or stone covering has cracked.
If it's not absolutely over the top, problems do occur. There are some ways around it occasionally, depending on the type of joint in the screed, but you would need to take expert advice from movement joint specialists as to whether it's possible in the specific individual application. As a rule of thumb, though, they must be directly over the top.
The surface covering of tile or stone will crack because it's rigid, and you're installing it over a flexible substrate. By lining up the movement joints in the surface, with the joint in the substrate, you're creating individual areas where the substrate and surface move together, preventing cracking.
However, Schlüter-BEKOTEC is actually changing the way subfloors and screeds are constructed. If your project is at the design stage you could install this modular screed system which doesn't need movement joints in the substrate at all.
This type of specialist screed underlayment system produces a thin, stable screed, without the need for movement joints or reinforcement. Then it wouldn't matter so much where your surface movement joints are fitted, as long as they fall within British Standards Institution guidelines.
Because there are no movement joints in the screed requiring surface joints to be placed immediately over the top of them, there is much greater flexibility in the tile design. There is no need for the surface to follow movement joints in the screed, or extend surface movement joints down into the screed.
One version of Schlüter-BEKOTEC, Schlüter-BEKOTEC-F, has a total assembly height of just 31mm, compared to a traditional screed of 75mm, making it ideal for use in areas where floor height is an issue. When used as part of the Schlüter-BEOTEC-THERM underfloor heating system, the reduced screed mass gives lower running costs and is quick and easy to regulate.
Conventional cementitious or anhydrite screeds can be used over the Schlüter-BEKOTEC underlayment. The screed system will not warp, and no continuous cracks will appear. The reduced screed mass results in a weight of approximately 57 kilograms per square metre - which is approximately half the weight of a traditional screed. and a reduced screed quantity which has a positive impact on the static calculations of new construction or refurbishment projects.

http://www.schluter.co.uk/2833.aspx

[Dave]

Modular Screeds

Schlüter-BEKOTEC is an underlayment which allows for easier installation, and is far less labour-intensive than traditional floor construction. It assures a crack-free ceramic tile and natural stone covering above a screed and insulating layer. The screed can be installed with or without underfloor heating pipes. Surface movement joints are only required in line with industry recommendations, and can therefore be incorporated to suit any aesthetic design of the tiled floor. A studded polystyrene panel is placed either directly over a load-bearing substrate, or over traditional acoustic/heat insulation. Stress build-up due to shrinkage, which occurs during the curing of the screed, is successfully eliminated by the formation of micro-fine cracks, doing away with the need for movement joints in the screed.
Basically, the studs on the panel result in an intentional weakening of the underside of the screed layer through their even spacing. When the screed shrinks, the network of micro-fine cracks forms between the studs. Consequently, the screed slab loses its compressive stresses, so the forces causing curling and cracks simply cannot accumulate.
As soon as the screed can be walked on, the Schlüter-DITRA uncoupling membrane is bonded to it, and ceramic tile or stone coverings are then installed on top, incorporating surface movement joints in line with industry recommendations. Coverings which don't crack -- such as carpet and vinyl -- can be fitted as soon as the screed has dried sufficiently.
Because of its lighter weight and lower assembly height, it is installed faster than traditional underlays, the screed does not curl, and, most importantly, the surface coverings are guaranteed crack-free.
Heat or sound insulation can be placed below the system to comply with building regulations - something which, with traditional methods, can be a major problem when applying rigid surface coverings such as ceramic tile and stone.
However, if heat or sound insulation is required below the screed, it should be selected to conform to the applicable standards, and must be rated for the particular live and dead load exposure. Obviously problems may arise if unsuitable materials have been used in the flooring assembly. But problems which do occur can be repaired by cutting out the damaged areas, and repairing from the underlayment system through to the surface covering.
The suitability of the system to withstand high loads in individual applications should be verified. However, the breaking tests performed on the modular system exceeded the 2 KN/M2 required by DIN 1055 for residential and commercial applications such as offices, public buildings and car showrooms.
An "Expert Report" prepared independently by IFF Koblenz, a well-established name in the German flooring industry, concluded that Schlüter-BEKOTEC's modular technology can "rightly be considered a new and innovative solution for common problems on today's construction sites."
The report states that the system gives:

• No warping or curling of the screed slab
• No cracks in covering materials made of ceramic or stone tiles
• Sufficient live loads for the application areas up to 5 kN/m2, depending on insulation materials
• Low construction height
• Fast installation times
• Time-saving and cost-efficient construction processes
• Economical energy utilisation in floor heating systems.

Modular Screeds - Schlüter-Systems

[sWe]

I like the technical stuff

[Rob Z]

We got to work with Bekotec when I attended a Schluter training session in South Carolina. It is neat stuff, but I haven't had the call to install it on any of my jobs. I think it could be used a lot in the northern US where there is a lot of hydronic heat installed in floors.

[doug boardley]

very interesting stuff Dave, like Marcus, like to try and get my head round the tech stuff ( altho Marcus probably doesn't have to try! lol!)

[whitebeam]

Did do the schluter day and found it an eye opener