Which personal contribution is worthwhile in house construction?

For our new construction, we carry out the following work ourselves.

Electricity: chasing, drilling boxes, setting boxes, pulling cables
300 hours with about 150 boxes. Savings according to our electrician approx. €5000.

Gutters: 57 hours. We have a hipped roof and also a hipped roof on the garage. Savings here less than €1000.
But it was fun.

Roofing: Underlay and counter battens were done by the builder, so we only had to do the roofing.
Effort 200 hours. Savings exactly €7350.

The following own work is still pending.
Laying screed insulation, laying underfloor heating
Savings: €3300

Painting, wallpapering, outdoor area.
Savings: ?

One must say about all this, we were three. Father, father-in-law, and me. Almost every day from 4:00 pm to 7:30 pm
and every Saturday from 10:00 am to 6:00 pm.

Great examples! So far, only the roof has really been worth it. The electrical work and guttering can be questioned depending on one's own income (+execution quality, duration, and possibly warranty)

In some countries, people are trained to be "specialist idiots." You are supposed to only know one thing, but to do it well. For all other activities, the money should change owners and be taxed. For the state, a very lucrative business model.

Of course, we would officially commission the mason friend's company. He is not supposed to do the work off the books for us but bill it normally. The idea was just that we save on one worker from one of his employees. (The same applies to the electrician), by the way, it was an idea from the mason friend. We also do not expect the house to be completed within 6 months. Therefore, I find a cost estimate for the individual trades interesting. The question is whether we should help more at the beginning (really the shell construction with the friend) or during the interior work. So exactly how my husband should schedule his 6 months off during the construction phase.

I would recommend interior finishing. Why? Heavy loads are moved during shell construction. You are always exposed to the weather. Back strain or catching a cold here and there is usually inevitable.

I felt that the shell construction was less labor cost intensive than the interior, but after adding it up, it’s been about equal so far, 640 outside to 700 inside. Hours. The shell construction was somehow faster, but there they were mostly four people, inside mostly two. Karsten