Construction costs are currently skyrocketing

There needs to be battens underneath, I was told at least 5cm of ventilation. So you take battens 40x60 upright, screw them on, and across that the rough decking. Of course, pre-drill for the screws.

I doubled up to get the spacing. The insulation should not have permanent contact with the boards so that air can flow through and carry away moisture. You just have to see how much space is left. I would leave about 3-4 cm... If the boards already cover the entire length, you don't need to create an offset. In my opinion, you don't have to on the floor anyway. It's only about the fact that the joints can sometimes widen due to movement and it doesn't look so gaping in the offset. In the attic, it's actually irrelevant.

There has to be a battens underneath, I was told at least 5cm of ventilation space.
So you take battens 40x60 vertically, screw them on, and then the tongue and groove boards crosswise to that.
Of course, pre-drill for the screws.

With floorboard screws, you don't have to pre-drill. They are specially made to be screwed in directly.

Our general contractor told us I can lay it directly on the beams. It's wood, so it doesn't seal tightly. But I only covered the middle part, left the insulation open around the edges, because we don't need that much space anyway. So far, everything has been dry for 1.5 years.

But with a batten underneath, you definitely can't go wrong.

You don't necessarily have to stagger if the boards are already the right length. If not, I would just do it anyway because it doesn't take more work. You take the end piece again at the front, and you have to cut anyway.

You don’t have to pre-drill for floorboard screws

He probably means for the moldings. It’s better that way, otherwise they tend to split. I agree about tongue and groove boards, you don’t have to pre-drill them with floorboard screws.

If it were only the 60-70/h being billed, one could consider for many jobs whether the craftsman isn’t a good choice.

With 30k for heat pumps, where the material accounts for at most half (and is definitely available for 10k), the installers would have to work for at least 15k in wages, i.e. 200+ hours. But they are at most busy for 6 days with a journeyman and an apprentice. The rest goes into the pockets of the overpriced [WP manufacturers] and bosses. That is the outrageous part, not that 70€/h is charged for professional work.

In the meantime, I have had so much hassle with craftsmen and other service providers – I do everything myself that is not forbidden.

Cost plan for complete renovation of former barn with conversion to living space (really only brick walls and floor slab inside and concrete ceiling without insulation): around 90k for 100m2 – of which 10k are architect fees for the building application, 2k for structural engineering and thermal protection certificate, 20k for the [historic preservation barn windows], and the electrician with 3k for fuse box and inspection. The rest is material.

So if I screw squared timber into the roof structure or floorboards onto the squared timber, I prefer to pre-drill. I definitely do not take the risk of splitting a rafter in my roof structure.

The 50mm ventilation is stated like that in my handover documentation for the house. It would be stupid if I deviate from that. The point is that moisture that may arise in a special situation can escape.

And to end the debate for me. Sure, the professional can sometimes do it better than me and faster. But whether under increasing pressure he really does it better... and not just faster. I sometimes have my doubts. Given my income situation, it looks like I have to work a good 3, almost 4 hours for a craftsman’s hour at 70, 80 EUR. In my case mostly field service, so the whole day or even the entire week, sometimes a whole month away from home. You really reconsider if you can’t do it yourself.

And it doesn’t have to be 100%, especially not if you do it yourself. This standard is relatively new, I claim it only came into fashion in my generation (born 1983), rather later.

Everything has to be immediate. If the kitchen gets 2 ovens, they have to be there at move-in, otherwise please install blanks. Absolutely no inserts are allowed to remain empty for several months, etc.

Don’t get me wrong. If you can afford it, please. That’s what craftsmen live on. But most just can’t afford it. That’s why the loans are spiraling out...

That’s going to blow up in "our" faces...