Roof insulation hip roof new building KfW 40

You write that heat and cold protection are two different things. I know you understood me ;), could you please show me where the difference lies and what I could do better as heat protection.

No, I did not write about heat and cold protection, but about heating energy loss (= wasted money that you do not want to throw out the window) and thermal insulation in the other direction (= against unwanted heat input or against too slow re-emission of absorbed heat or against unwanted addition of expended heating energy and radiated heat). But that is now too complex a topic for this time of night and has to wait until my not too hot night is over :)

Thank you for your once again very enlightening words :D.

I am very curious about your fresh answer. I hope this complex topic can be put into words that even I can understand o_O.

We will be out all day again tomorrow, so I will probably only get to reading in the late afternoon or evening, but I am already looking forward to it…

Good night…

Because if the roof is not insulated directly, the room under the roof is like a sauna in summer and I sleep under this sauna.

No, the ceiling of the upper floor is insulated after all.

If the 25 degrees is that important to you, plan for air conditioning right away. It simply wasn’t clear to me either because I’ve always lived in “old” houses... but the most important thing is: A new house stays cool for a long time, but once the heat is inside, and it eventually will be, you can’t get it out by ventilating anymore... The walls are then heated up and when you close the window it gets warm again right away... Bedroom facing northeast helps, shading too... But there will still be nights when you feel it’s too warm for your liking... I also imagined that with the bypass function of the controlled residential ventilation I could do something about it: but it doesn’t help much...

I would prefer to install the air conditioning directly and simply see if we need it, and then just use it for one or two days as needed.

Unfortunately, all the homeowners agree, including our favorite. It is not compatible with KfW 40, not even the pre-installation for it. I would have preferred to have it pre-installed to then possibly bring a split unit into the bedroom without problems; that would certainly be easier than having to do it afterwards.

Nevertheless, I would of course still prefer to manage without it, which is why the topic of insulation is so important to me.


I have understood that by now, just not quite figured out yet why this variant is better than keeping the heat out of the house directly through insulation right at the roof. The oven above the insulation in the upper floor ceiling probably also needs more time to cool down at night, right?


@all Well, maybe (hopefully) I will be enlightened here about how the whole thing behaves so that I can understand it too. Until then, I have one more comment :). I have also read in one or another construction service description about combined insulation. Insulation of the ceiling on the upper floor plus under-rafter insulation. Could that possibly be an option for this?

Why do you really want the 40Plus? I don't see any advantages in it except for the costs.