Roof insulation polyurethane PU rigid foam 100mm thick

Basically, every insulation material eventually gets hot during summer temperatures, especially when exposed to direct sunlight. The phase shift is about delaying the heat transfer into the living space until the evening and nighttime hours when the indoor air and walls can be cooled down again through ventilation. I recommend reading about this on the internet. Therefore, the phase shift should be at least 10 hours or more. Even more important for heat protection is that windows are possibly shaded by blinds or roller shutters.

We have 25 cm Gutex wood fiber roof insulation and the soundproofing is a disaster. You hear everything through the roof as if it weren't there at all. Airplanes are very disturbing even though they are over 5000m high, the whole roof vibrates.

Good morning... @ Dachausbauer, Thank you for your detailed report... very interesting. You are absolutely right. All craftsmen told us to use the exterior insulation on top of the rafters. Further insulation measures would then not be necessary. But that is exactly not the case. As far as I can see, you cannot avoid insulation between the rafters. But roofers NEVER offer that. We were offered the PU boards "puren Protect N023" and nothing else. And from what I have read so far, they are a disaster when it comes to sound and thermal insulation. @ Garfunkel, You have these PU boards with a mineral wool layer? Only 5 cm? That’s really little, isn't it? Are you satisfied with the heat protection? So you also don’t have any insulation between the rafters? @ Bookstar, You have 25 cm wood fiber exterior insulation on top of the rafters and the sound insulation is a disaster??? My God, what should one ultimately choose???? How does the heat protection look like for you? You probably don’t have any insulation between the rafters either, right??? Many thanks to everyone!!! You have helped me a lot so far. Thanks + best regards Anke

without having read everything: sound and heat protection are important. The craftsmen are right, additional insulation is then NOT necessary. If the money is available and left over, I would additionally do insulation between the rafters and a small insulation below the rafters in addition to the roof insulation. I would then additionally put a layer of OSB boards quite far towards the interior side of the room. The motto for airborne sound and heat protection is: mass is power. The whole thing can also be done cheaply as a DIY project. If possible.

Joe, couldn't we then omit the over-rafter insulation and only insulate between/under the rafters? After all, it's an old house, and the Goggo won't turn into a Ferrari.

Hello and , yes, our house is an old building / with ceilings made of wooden floorboards. @ Joedreck, yes ok, no further measures besides exterior insulation are needed, right? But for us, it's not "just" about cold protection now, but also about SOUND & HEAT protection. We were offered 100mm PU boards. In your opinion, should we also install insulation between the rafters because of sound and heat protection? And yes, we can manage that ourselves. @ Nordlys, everywhere and literally every roofer swears by the exterior insulation above the rafters. Everyone has recommended this measure to us. But as I said, we are totally uncertain about heat and sound protection. Thanks to everyone!!! Best regards Anke