Dry floor truss roof boarding

Also, according to the site manager, and I find this the most absurd thing, there wouldn’t be any space for the insulation anyway, since the insulation sticks out about 4 cm higher than the beams..., so it basically protrudes from the beams

So the structural ceiling beam thickness would be less than the thickness of the insulation to be installed between them - who plans such a foolhardy thing? - that would basically mean corresponding battens in the insulated area. Apparently, the use of the attic storage space has (incredibly) not been planned – by “project planner” do you mean just a dispatcher of the involved installation crews (or a sales consultant who is supposed to mother the order until handover)?

the drywall installer when installing the insulation in the attic into the timber beam layer / i.e. the ceiling of the masonry

I hope you realize how far our ignorance of your construction project reaches – it almost makes it impossible to form the necessary minimal understanding of the specific conditions. What “ceiling of the masonry” is supposed to mean is beyond me. The drywall installer – I can only painfully deduce – is supposed to panel the ceiling beams from below in order to be able to lay the insulation. In a truss roof, I assume – but that’s only me, you can’t remotely expect the average forum user to be able to mentally immerse themselves so deeply in a verbal house description – that the ceiling beams at the same time are the underside of the rafters. So, what exactly has the drywall installer logically got to be fiddling with there if the crane operator hasn’t already drone-suspended the boards with the trusses? – Apparently someone has even two left hands so that the right hand doesn’t know what the left is doing. Oh dear, Lord, please drop some brains from the construction crane!

Maybe you’ll quickly show the house in question now – this definitely won’t be the last fire brigade deployment against the neglected planning.

It was done exactly as you described with me: The tongue and groove boards were laid on the beams while the roof was still open. However, everything was coordinated by the GÜ, so I am not aware of any problems regarding the drywall installer.

I only know it as the OSB boards, as your general contractor suggested, being lifted by crane through the roof that is not yet in place. The OSB boards are then laid and later the drywall installer insulates the floor ceiling from below. And that the insulation protrudes 4cm upwards I have never heard.

and later the drywall installer insulates the floor ceiling from below. And I have never heard that the insulation protrudes 4 cm upwards.

Apparently, the following procedure is used here: the drywall installer first closes the "ceiling" on the underside with paneling and then inserts the insulation—which is otherwise more commonly placed on the ceiling—as a kind of "inter-rafter insulation" there. The consequence, that in the interplay of no more than statically necessary "beam height" and insulation thickness the overall construction is not ready for covering, is of course a foolish deed, because the attic then naturally cannot serve as a storage room. In the areas to be serviced, one logically has to add battens. Here Max and Moritz have obviously encountered Widow Bolte.

Thank you for your hints. I spoke again with the project planner who is supposed to oversee the construction project from start to finish. (It is a general contractor.) After initial confusion and checking, she said that the thermal transmittance, I think that's what it's called, was changed from 040 to 035 (I subsequently upgraded to KFW55) due to different material and not because of increased thickness. Apparently, the construction manager wasn’t paying close enough attention here. Hopefully, that’s correct.

But one more question. If the insulation ends flush with the roof beams, do you then need to install a substructure on the roof beams or can the OSB boards or tongue-and-groove boards be attached directly to the beams? And which is better, OSB or floorboards? It is a "cold" roof. So the vapor barrier and insulation, as mentioned, are in the ceiling (wood beam ceiling) or the floor of the attic. How far do you board out? Actually only the walkable part of the hipped roof or further underneath the slopes? By the way, I will offer the construction manager to carry the boards/floorboards myself from A to B if it’s too much for the drywall installer. Then the "lifting into the roof with the crane" shouldn’t be a problem. Hopefully!

Don't burden yourself with carrying that stuff up, it should be flown in with the crane. And again: if the drywall installer is already messing around there beforehand, they were scheduled too early (i.e. your operating request was probably not taken into account, the wonderful project lady is supposed to fix that). I would only operate in the area that is to be accessed / used. As a reference example for a bungalow attic, you can use the one from here in the forum. Regarding tongue and groove or OSB, you will surely find enlightenment through the forum search, where tongue and groove (note: also try "modern" without an h in the search) is seen to have better moisture properties, but I only half-listen to these aspects, so take a look at the related posts yourself. Personally, tongue and groove or even Sauerkraut boards would be "good enough" for a storage floor in my opinion; and I also don't see any drama in the compression of the insulation wool (if you don't elevate for that) - but again: not my area of expertise.