ᐅ Number of Heating Circuits in a Thin-Layer Screed

Created on: 19 Dec 2023 15:05
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LostWolf
Since my maximum installation height is unfortunately very limited (max. 50mm (2 inches)), I have to use a thin-layer screed system. Schlüter offers a suitable system with Bekotec. It provides the option to choose an installation spacing of either 75mm (3 inches) or 150mm (6 inches).

What pipe length per m² can be expected with these spacings? Unfortunately, I only find information online for 100mm (4 inches) or more: for 150mm (6 inches) spacing, it would be around 5.8m/m² (Schlüter’s own calculator indicates approximately 6.7m/m² -> which one is correct?). How much pipe length per square meter would it be with a spacing of 75mm (3 inches)?

For example, with my roughly 35m² (375 ft²) living room, this would already result in 6 separate heating circuits if I want to keep each circuit under 100m (330 ft).

How should I decide which spacing to choose, and would 15cm (6 inches) spacing be sufficient?
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xMisterDx
23 Dec 2023 18:11
How does the compressive strength hold up when, in the end, there is more pipe than floor surface to cover?
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LostWolf
23 Dec 2023 18:19
Good question. But the manufacturers must have had a reason for specifying this installation spacing as acceptable.
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jens.knoedel
23 Dec 2023 20:45
xMisterDx schrieb:

What about compressive strength, especially when there’s more pipe than floor surface to cover in the end?
That’s exactly why there is a minimum pipe coverage requirement, ensuring you have a continuous minimum screed thickness — which usually also matches the minimum thickness for floors without underfloor heating. Therefore, the pipe spacing is irrelevant.
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xMisterDx
24 Dec 2023 11:32
That doesn’t make sense. What happens with a joint spacing of 0? The screed layer, no matter how thick, is not self-supporting like a concrete slab. It is supported from below... Well, it will probably be fine anyway 😉
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WilderSueden
24 Dec 2023 13:54
In reality, no one installs with a spacing of 0cm. At 7.5cm (3 inches), there would still be about 85% screed coverage, which is not an issue with appropriate overlay.