Question about soundproofing with drywall

I have double-sheathed (OSB & GK) mainly for reasons of summer heat protection; sound insulation was not so important to me.

Well, whether 12.5 cm of plaster contributes that much to heat protection??

In theory, according to the u-value calculator, that already brings quite a lot, but only the roof as a single component is considered. In a solidly built house, which already has a high internal mass (concrete ceilings, etc.) as a heat storage, it probably does not bring much improvement in the end, that is true.

I would use thicker rafters - at least 24 cm - and have the cavity blown with cellulose at a higher density (approx. 60 kg/m3)

If then inside 40 or 60 mm thick wood fiber boards are placed between the cross battens, this insulates even better
and overall has much better sound insulation as well as summer heat protection.

Then you can first see if simple sheathing is sufficient

Andreas Teich Gebäude-Energieberater/Bauberatung

Hello Andreas,

and overall has much better sound insulation as well as summer heat protection.

I would agree on sound insulation; regarding summer heat protection, I can report from personal experience that there is nothing, absolutely nothing – except an air conditioning unit – that makes a converted attic bearable on summer days.

Rhenish greetings

Hello Andreas,


I would agree on soundproofing; regarding summer heat protection, I can report from my own experience that there is nothing, absolutely nothing - except for an air conditioner - that makes a converted attic bearable on summer days.

Rhenish greetings

I think the focus should be on the word "better" summer heat protection...

Most of the heat comes through windows that face the sun and do not have external roller shutters or when these are not used.

We also had unbearable heat in the summer in the upper floor of our newly built house, worse than in the old building before... Since the roller shutters have been there and are also lowered (time programmed), it is sometimes almost too cool up there, the difference is really intense.

Of course, to use an air conditioner, the roller shutters can be left out; ideally, the windows would also have power generation in the panes as used in large glass buildings =) Basically generating electricity through the glass facade to operate the necessary air conditioning.