Insulation of the top floor ceiling

Then you have 240 mm, that is quite a lot I think.

Regards
Specki

I have 50cm, you can't insulate cheaper than that.

Well, 50 cm is too little for me. I thought 160 mm should be pretty good. The question is simply how much more it brings if I add even more... but that probably won't be easy to determine.

Well, 50 cm is too little for me. I thought 160 mm should be pretty good. The question is simply how much more it brings if I add even more... but that probably can't be determined that easily.

50cm, not 50mm

Sorry, misread.

But that is a bit too much for me then.

Did you use the u-value calculator? There is a lot of information in there; you can even calculate the payback period if you know how much the measure costs per m², from when to when you heat, the costs for heat generation, and the price increase. So for you maybe €7 per m² based on the area being 100m². With that, you can probably use 160mm insulation. + other ceiling construction as specified (except that I added 3cm mineral wool to the screed because of the tool). Heating for a warm apartment, from O to O 10% price increase and 10 cents for 1 kWh heat calculates a payback period of 1.8 years at 140mm insulation also 1.8 years 140mm energy saving 35kWh/m² 160mm energy saving 37kWh/m² 200mm energy saving 39kWh/m² 220mm energy saving 40kw/m² 500mm energy saving 45kWh/m² (payback period 1.4 years) Calculated with rough data; if you can enter your planned setup exactly and know the data for the calculation, it is very easy to find out relatively accurately whether, when, and by how much it pays off (could). For a free tool, an absolute recommendation that you can safely look at for such a project

I consider a payback period of 1.8 years or something similar to be unrealistic. Last year we had a gas bill of about €1450 and burned wood worth about €350, so a total of €1800. It is a two-family house. Two apartments one above the other, each full floor with the same layout. If I now insulate the top floor ceiling, it will probably only really make a difference in the upper apartment (where I live). I believe the lower party heats quite a bit more, so I estimate heating costs of €800 for us. If things go well, I might save €100 to €150, that would already be something. Then the matter would pay off after about 5 to 7 years. I would already be happy with that. Yesterday I ordered insulation wool with 180 mm, WLG 035. A total of 105 m², for €740 including shipping. Regards Specki