ᐅ Loose-fill insulation around pipes vs. insulation boards

@ "Tushan79"
From what I see, you haven’t really received a practical answer to your technical question yet.
Your idea with the infill is good, but not in the order you planned.
Knowing that you need a total build-up height of 11cm (4.3 inches) makes things easier.
Subtract twice the insulation thickness from the 11cm (4.3 inches) to get the height you should fill with a bonded infill on the structural slab.
The installation pipes are then embedded in the infill, and the first layer of insulation is cut out around the pipes so that the top edge of the first insulation layer is flush with the top of the installation pipes.
Only after that is the entire floor area covered continuously with the second insulation layer. On top of this goes the fixing panel.
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Good luck: KlaRa

KlaRa schrieb:

@ "Tushan79"
From what I see, you haven’t really received a useful answer to your technical question so far.
Your idea with the screed is good, but not in the planned order.
Knowing that 11cm (4.3 inches) is the required total build-up height makes things easier.
11cm (4.3 inches) minus twice the insulation thickness is the height you should fill with a bound screed on the raw ceiling.
The installation pipes are then embedded in the screed, and the first insulation layer is cut out around the pipes so that the top edge of the first insulation layer matches the top edge of the pipes.
Only then is the entire floor surface covered with the second continuous insulation layer, followed by the fixing (tacker) board.
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Good luck: KlaRa

Hello and first of all, thank you very much for the answer!

KlaRa schrieb:

11cm (4.3 inches) minus twice the insulation thickness is the height you should fill with a bound screed on the raw ceiling.

I didn’t quite understand that.
Let me summarize my plan for the ground floor again according to my understanding:

• Pipes (2cm (0.8 inch), 5cm (2 inches), 6cm (2.4 inches)) have already been laid on the floor
• I lay the first insulation layer (6cm (2.4 inches)) floor-wide and cut it out around the pipes accordingly
• The "gaps above the pipes" are then filled with bound screed up to the top edge of the first insulation layer
• Then the second insulation layer (5cm (2 inches)) is laid entirely over the whole floor without gaps
• Finally, the 3cm (1.2 inch) fixing mat is installed on top

Is that correct so far?

If yes, then I still have a question regarding the upper floor:
Here we have rooms with only 2cm (0.8 inch) pipes, others with 5.5cm (2.2 inches) flat ducts and 2cm (0.8 inch) pipes, and the hallway with 8cm (3.1 inches), 5.5cm (2.2 inches), and 2cm (0.8 inch) pipes.
We have already ordered 6cm (2.4 inches) and 2cm (0.8 inch) insulation boards (due to anticipated price increases).
What would be the best order to lay these boards?

I see two options here; which one would you recommend?
a) Lay the 6cm (2.4 inches) boards over the entire floor first, cut out around the pipes, fill above the pipes with screed up to 6cm (2.4 inches), then cover the entire surface with 2cm (0.8 inch) boards (only the 8cm (3.1 inches) pipes would need to be cut out here)
b) Lay the boards depending on the room. That means: in rooms with only 2cm (0.8 inch) pipes, lay the 2cm (0.8 inch) boards first and then the 6cm (2.4 inches) boards on top. In all other rooms, lay the 6cm (2.4 inches) boards first, then the 2cm (0.8 inch) boards on top. The only question is how to handle the transitions between rooms, since there will naturally be a transition somewhere.

And one last question:
Can you recommend a screed product? Currently, we are discussing Fermacell and Mehabit. Are there clear advantages or disadvantages with either product?

Thanks in advance for your help

Does anyone have a few answers to these questions for me?

Tushan79 schrieb:

Does anyone have some answers to the questions for me?

Well, I have already answered all the questions as far as the technical basics are concerned.
If you run pipes of different diameters across the raw floor slab but want to avoid steps between rooms (which can be assumed), then your only option is to transfer the highest point of all pipe installations to every room.
And this is only possible with a bonded screed.
The bonded screed always forms the bottom layer on the raw slab. Any other methods, like "installing insulation material according to the Oberallgäu woodcarving principle" (meaning the pipe installations are intricately cut out in the insulation boards) are, to put it bluntly, botched!
Locate the highest point, transfer the height to the other rooms using a rotary laser, fill up to the top edge of the highest point with bonded screed, and then—depending on the available construction height in the room—install a coverboard made of MDF and on top of that one or two layers of insulation boards with staggered joints.
Best regards and good luck: KlaRa

I’m joining the discussion here.
We are installing our 90mm (3.5 inch) ventilation ducts on the concrete slab, which means we will have a “higher” build-up.
However, we have significantly less insulation above the ventilation ducts, so we are planning to use

• 100mm (4 inches) insulation (70mm (2.75 inches) loose-fill insulation and 30mm (1.2 inches) polystyrene)
• 20-2 staple board and then
• 60mm (2.4 inches) screed

resulting in a total of 180mm (7 inches) plus the floor covering.

Now I’m reading from @KlaRa that the recesses—in our case the polystyrene boards—are not a good idea… So it would be better to use only loose-fill insulation? Then I wonder why the screed installer offered this mix?

Edit: [USER=58094]@Tushan79, why the additional insulation above the ducts?

Jentopa schrieb:

Now I read from @KlaRa that the cutouts – which in our case refer to the polystyrene boards – are a botched job... So is it better to use loose-fill insulation completely? Then I wonder why the screed installer offered this kind of mix?

Answer:
In the industry, these patchwork-type jobs on the board-shaped insulation layer are jokingly called "Upper Allgäu woodcarving."
Why the screed installer offered this kind of work remains his secret.
With a pumpable leveling layer made of cement, water, and size-controlled polystyrene beads, he would be faster and could work cleaner.

Edit: @Tushan79 why the additional insulation over the pipes?

Answer to this:
The leveling layer is not to be confused with a classic insulation layer, as required under floating screeds.
Manufacturers often offer additional material properties as a side benefit, but ultimately they cannot match insulation materials whose sole purpose is thermal or impact sound insulation!
Therefore, the Federal Screed & Flooring Association (BEB) also requires that a continuous insulation layer is installed as the final step.
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I hope this answers the question.
Regards: KlaRa