ᐅ Increase the finished floor level of the living area

nordanney schrieb:

Insulation on the terrace and inside below the ceiling (e.g., PUR or phenolic foam with aluminum facing).

Yes, we also once considered insulating below the ceiling, but then the rooms in the basement would have different ceiling heights, since not all rooms are under the terrace.

nordanney schrieb:

For example, I’m insulating my 1960s old building externally with only 12cm (5 inches) phenolic foam to easily meet KfW 55 standards.

And nothing inside? That would, of course, be the simplest solution, just using thinner insulation. But usually, you’d discuss that first with the energy consultant, right?

I was also thinking about whether you could "bridge" the height more cheaply with wooden battens, for example, and OSB boards or something like that. Or would that cause problems with the underfloor heating?

Fritsch schrieb:

What does “klauen” mean?
I’ve attached a section drawing.

Unfortunately, you only showed the section. But the ground floor (GF) was probably not actually “stolen” or erased, rather you are creating confusion on a semantic level by calling it a “basement.” The section drawing actually just shows a GF and a first floor (FF), no third level.

Fritsch schrieb:

Because of the insulation of the basement ceiling under the terrace, it is higher than the living space on the GF. This height difference is supposed to be evened out with screed.

That is utter nonsense, a design failure beyond belief, you might think, but:

hanse987 schrieb:

This reminds me a bit of the “robber’s house.” You didn’t notice it on the plans, only once the shell construction was up.

No, here it gets even worse (if you actually implement that half-meter-thick (!!!) floor build-up on the FF) — because then you’d be down to a passage height of a mere 1.61 meters (5 feet 3 inches) for the terrace doors! — I linked that robber’s house example for good reason.

Fritsch schrieb:

Yes, we also once talked about insulating below the ceiling, but then the rooms in the basement would have different heights,

Yes, do exactly that: split the insulation, place it partly above and partly below the ceiling, both with materials compressed to the necessary thickness. You will also have to solve the water ingress issue at the terrace door threshold constructively, which will cost additional height. You might need to scroll back a bit at the linked post; this detail alone spanned seven pages as far as I remember. Visually, don’t worry — this can be cleverly chamfered and hidden in such a way that it results in an interesting ceiling underside. With some luck, all your friends will later ask who built that stylish “design flaw” for you. That might just become a trend 🙂

By the way, screed alone will not compensate for this, only with a - structurally massively unnecessary - triple layering of insulation underneath. What does your general contractor do for a living — butcher? *SCNR*

---

https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/

Fritsch schrieb:

Yes, we had also discussed insulating below the ceiling, but then the rooms in the basement would have different heights since not all rooms are located under the terrace.

And? This happens in many houses where some rooms have dropped ceilings for spotlights and so on. We are only talking about small thicknesses anyway.

Fritsch schrieb:

But you usually discuss this first with the energy consultant, right?

Yep, plus the house designer/planner.

As nordanney wrote, PUR tapered insulation, for example from 160 mm to 100 mm (6.3 inches to 3.9 inches), should easily meet KfW55 standards (this is also our planned approach). However, it also depends on the type of terrace construction (surface layer) you want. If, for example, you choose WPC decking or similar, the overall layers might look something like this:

- WPC + aluminum substructure: 80 mm (3.1 inches)
- Protective mat: 16 mm (0.6 inches)
- EPDM membrane: 6 mm (0.2 inches)
- PUR insulation: tapered from 160 to 100 mm (6.3 to 3.9 inches)
- Vapor barrier: 1.5 mm (0.06 inches)

This adds up to about 263 mm (10.4 inches) total thickness, leaving around 40 mm (1.6 inches) of tolerance (if I’m reading the plans correctly, you actually have about 30 cm (12 inches) total from the top of the concrete slab to the finished floor level inside, right?).

With appropriate measures in place (guttering, etc.), you can also go for a zero-threshold patio door, provided your general contractor agrees.

If space is very tight, vacuum insulation panels are another option for a thinner build-up—but they are considerably more expensive and can quickly become unaffordable depending on the total area.

Hello everyone,
first of all, many thanks for the many helpful answers.

Maybe to start with the basics: the house is built into a slope and therefore has a basement level with an attached garage and a ground floor (with the terrace).

I just took another close look at all my documents (cross-section, energy consultant calculations, and general contractor’s quote) and I think I forgot something important. The ground floor with the terrace is partly located above the garage and therefore also needs to be insulated. (Unfortunately, the terrace couldn’t be placed above the garage because the garage has to be on the east side due to the gentler slope of the plot there, while the terrace should be on the west side.)

In the energy consultant’s documents, the total floor construction thickness is 55cm (22 inches) for the living area, considering the reinforced concrete slab at 25cm (10 inches), and for the terrace only 47cm (18.5 inches) with a 20cm (8 inches) reinforced concrete slab. The general contractor’s quote specifies a slab thickness of about 20cm (8 inches).

Now I am a bit confused about the different concrete slab thicknesses. And isn’t an 8cm (3 inches) height difference too much? Or is it just a 3cm (1 inch) height difference and the house is 5cm (2 inches) lower? Is this feasible without changing the exterior plaster? I definitely need to clarify this.
Nevertheless, the floor buildup of the terrace determines the height of the floor buildup inside the house, right? So, without the terrace, a lower floor buildup on the ground floor would theoretically be possible, correct?

I hope I was able to express myself clearly. Thank you again.

Fritsch schrieb:
I hope I was able to express myself clearly enough.

So-so – like many other people asking questions, you lack the awareness that we can’t read anyone’s mind here, and therefore we always seem clueless about the background knowledge until someone clarifies the context with some pictures.

---

https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/