Insulate concrete ceiling upper floor

So you mean that the aluminum-coated undersides of the PUR insulation boards will not be sufficient as a vapor barrier? You recommend additionally installing a vapor barrier?

Best regards

One can still learn after many years. Bauder follows the DIN and thus has a vapor retarder in the system.

... which, however, is not sold as mandatory by Bauder.

but the water vapor, as I assume that the house is inhabited.

... which can be neglected after passing through 16 cm of reinforced concrete.

Won't the aluminum-coated undersides of the PUR insulation boards suffice as a vapor barrier? You recommend additionally laying a vapor barrier?

That's what he thinks, because he knows better . You can gladly do that, it will neither make the structure better nor worse, just more expensive.

Who sells what doesn't matter. Bauder will not be stupid enough to recommend that, because then Bauder would be liable.
Furthermore, the system tests are very expensive; no manufacturer conducts them for fun, but because nothing can be installed without approval.
Of course, you can leave out whatever you want in private, since you are liable yourself.
The energy consultant will examine it and will not accept anything other than his result, for which he is liable.

Hi,

now I was interested in the actual structure of the top floor slab. I have now looked again at the input plan for the house section from back then.



What do you think? It seems as if the builders planned to lay a 5cm layer of screed on the 16cm reinforced concrete slab B225. I have now measured the thickness of the slab at the attic staircase and actually come to about 21-22 cm, which means it could very well be that they laid a 5-6 cm layer of insulation and screed on the reinforced concrete in the attic. Unfortunately, I know so little about the house (built in 1972), since I only acquired it in 2014. The old building plans also only indicate the B225 reinforced concrete, but no specification of the thickness.

I have now taken a more detailed photo of the concrete floor in the attic. Is that pure concrete or possibly a layer of concrete screed?



Would a possibly applied screed layer influence the planning at all?

Thanks to you.

Best regards

Would a potentially existing screed covering influence the planning at all?

No, only that the existing ceiling including insulation and screed would offer slightly better insulation than the bare concrete ceiling.
21-22cm of pure concrete would be unusually thick. In my mid-60s building, it was (and still is) 16cm of concrete and then 20mm of insulation + 40mm of screed.

BUT: In those days, Styrofoam was simply placed on the concrete without a vapor barrier or anything similar. Then you have to expect a swimming pool as a layer between the concrete ceiling and screed. LOL and irony off.

What do you think about the photo? Could the pavement be cement screed? Or does it look like the reinforced concrete ceiling?

I have now measured more precisely upstairs again. The area, without considering the chimney and wooden studs, is about 105 sqm. How much waste should I actually calculate? Is 5% extra enough? That means ordering for 110 sqm?

If I could assume that there is actually some insulation on top of the 16cm reinforced concrete, e.g. 20mm Styrofoam and then 50mm cement screed was laid, then I could perhaps just lay cheaper Styrofoam boards EPS 035... for example

Styrofoam multi-purpose insulation boards EPS 035 DEO dm/DAA dm/WAB -> 100 kPa

[*]Thickness 160mm
[*]Thermal conductivity group: 035
[*]Universal insulation, compressible
[*]Edge formation: butt joint

That would save me 500 EUR at about 15 EUR per sqm including shipping. That means about 1700 EUR instead of 2200 EUR for the PUR insulation boards (with shipping about 20 EUR per sqm).

I calculated once with the new intended setup with the 16cm Styrofoam boards EPS 035 in the U-value calculator:



I come up with a subsidizable value for this KFW individual measure and maintaining the 20% subsidy level. Do you think this insulation value is enough for the energy savings in heating costs, or should one invest the few hundred EUR more because the additional energy savings would pay off quickly?

For comparison, the setup with the PUR insulation boards:



Thx to you

LG