Hello. We are about to install a floating screed for the underfloor heating. The base slab is very uneven, with the level varying between 17.5cm (7 inches) and 19.8cm (7.8 inches). Therefore, the insulation and screed layers need to be planned accordingly. So, I can’t build the height of the construction higher than 17.5cm (7 inches) including the finished floor, right?
Normally, the screed is planned to be 4.5cm (1.8 inches) above the heating pipes. This is generally seen as the minimum thickness. However, how should the maximum screed thickness be handled? Do you have any experience or recommendations regarding this, especially related to the heating system? At the spots with 19.8cm (7.8 inches), I would have to apply about 2cm (0.8 inches) more screed. That means it would be 4.5 + 2 + 2 (for the heating pipes) = 8.5cm (3.3 inches). Could this cause any problems? Vinyl flooring is planned as the final surface.
Additionally, I would like your advice on what you recommend for insulating the spaces above the supply and return pipes. Perlite? Our screed installer has suggested expanded clay aggregate with some added cement.
Normally, the screed is planned to be 4.5cm (1.8 inches) above the heating pipes. This is generally seen as the minimum thickness. However, how should the maximum screed thickness be handled? Do you have any experience or recommendations regarding this, especially related to the heating system? At the spots with 19.8cm (7.8 inches), I would have to apply about 2cm (0.8 inches) more screed. That means it would be 4.5 + 2 + 2 (for the heating pipes) = 8.5cm (3.3 inches). Could this cause any problems? Vinyl flooring is planned as the final surface.
Additionally, I would like your advice on what you recommend for insulating the spaces above the supply and return pipes. Perlite? Our screed installer has suggested expanded clay aggregate with some added cement.
Mycraft schrieb:
DIN 18560 mentions up to 80mm (3 inches)...Above the heating pipes? That would mean the screed is nearly 10cm (4 inches) thick. Sorry, but after looking through the DIN, I can’t find any specification for the maximum height.Of course, I want to avoid significantly increasing heating costs or causing other disadvantages.
Regarding the insulation setup:
0.6cm (¼ inch) moisture barrier (two layers of 0.3cm (⅛ inch) overlapping)
6cm (2½ inches) EPS boards, thermal conductivity 0.35
Now I’m considering adding another 2cm (¾ inch) EPS boards with the same 0.35 rating, and on top of that a 2cm (¾ inch) tack insulation board with 0.045 thermal conductivity.
That would be three layers. Unfortunately, we already have the 6cm (2½ inches) boards on site, otherwise, I would have designed the layers more evenly.
With a 6.5cm (2½ inches) screed, the total thickness would be 17.6cm (7 inches) including vinyl flooring, which is planned throughout.
At 17.5cm (7 inches) in the middle, I am already exceeding the available space.
Alternative: I take the EPS boards and only a 3cm (1¼ inch) thick tack insulation. The insulation thickness would then be 9cm (3½ inches) instead of 10cm (4 inches).
Including vinyl, I’d reach 16.6cm (6½ inches).
This would also give me some room to switch later to tiles.
In the areas where the slab slopes down, I need a buildup of nearly 20cm (8 inches).
There, I can manage a screed height of about 9–9.5cm (3½–3¾ inches).
Would that be acceptable?
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