ᐅ Underfloor Heating – Subfloor Construction?

Good evening!
We urgently need advice. We have already researched online but have come across different statements:
Mid-terrace house, built in the 1960s, floor removed down to the concrete.
We want to install underfloor heating and have heard about dry construction underfloor heating systems. But basically, we have the following questions:
- How is the subfloor build-up usually structured? Sub-base layer – insulation – underfloor heating – screed – floor covering?

- Why does the underfloor heating need to be installed under the screed? Would it also work if installed above the screed?

- Is there anything else important to consider?

Thanks in advance for the answers.

Keks2013 schrieb:

- Why does the underfloor heating have to be installed below the screed? Would it also work above the screed?

There are many advantages: the screed protects the heating system, distributes the heat, and stores it.

Sounds logical and reasonable

Keks2013 schrieb:

We want to install underfloor heating... we have heard about these underfloor heating systems as dry construction systems.

Why dry construction? Where do you want to install the underfloor heating? Insulation can be placed under the underfloor heating, but alternatively also under the basement ceiling (then you won’t lose any room height).

Tell us more about what and why you are planning.

Superuser schrieb:

Why drywall? Where is the underfloor heating supposed to go? Insulation can be placed under the underfloor heating, but also under the basement ceiling as an alternative (then you don’t lose any ceiling height).

Tell me more about what and why you are planning.

But then we would have to lower the basement ceiling, right? We didn’t want to do that as an additional step. Do you mean in which rooms the underfloor heating should be installed? In all living areas. The drywall system is supposed to be much cheaper. For about 100m2 (1,076 sq ft), around €6,500, so that’s why we want to choose it. But as you can tell, we’re not really familiar with it.

Keks2013 schrieb:

Drywall systems are supposed to be much cheaper.

I think that’s a rumor.

Keks2013 schrieb:

But then we would have to lower the basement ceiling, right?

Yep.
Is the basement heated? How do you plan to insulate under the underfloor heating? How much space do you have? ==> Proper insulation is essential, no question about it. Otherwise, you’re basically heating the basement.
“Lowering” means, for example, buying 60/80/100mm PUR foil-faced insulation (2.4/3.1/3.9 inches), plus PU adhesive foam, and simply sticking the panels to the ceiling. That’s very affordable, costs a few hundred euros, and makes a big difference.

Have you had the heating system designed yet? Room-by-room heat load calculation and specification of the desired room temperature. Make sure to keep the supply temperature as low as possible.

Keks2013 schrieb:

Do you mean in which rooms the underfloor heating should be installed? In all living areas.

Why not in every room, if you’re going to do it anyway?