Single-family house without a basement - generate parking space elsewhere

These days, insulation is also installed between the ground floor and the upper floor.

However, heating and ventilation also take place within the ground floor and the upper floor.

And even an uninsulated roof does not create a zero difference between inside and outside. That means ventilation is necessary then as well.

Is that so? The uninsulated roof actually has a certain draft (I believe the foil sheets in our case only overlap in many places and are not sealed airtight everywhere). We couldn't ventilate our attic except through the hatch...

A lot of people probably do that wrong.

Correct. The cold attic remains dry only if there is air exchange. That means you need ventilation openings, however and wherever. An open ridge alone is not enough. Roof windows with opened ventilation slots alone are not enough. You also need ventilation tiles and/or ventilation grilles in the gable walls. This is then self-explanatory an effective but uncontrolled ventilation, which also helps against heat in summer. I have a climate logger in the attic and therefore know that the humidity has always been low over the past year.

Insulating an uncontrolled ventilated attic makes no sense. In winter the cold comes in through the ventilation, the insulation is ineffective. In summer warm air comes in, which may even condense on the insulation. The advantage that the thermal radiation from the roof tiles does not heat up the attic as quickly does not outweigh this disadvantage.

We couldn’t ventilate our attic except through the hatch...

That is enough, it doesn’t have to be a "Velux". However, I would prefer gable openings. Or did you mean the one of the pull-down stairs?

Yes, exactly! Only the retractable attic ladder. But I really don't know anyone who ventilates their attic...

But I would find that strange too... I build a house with controlled residential ventilation, so that the living spaces no longer need to be aired. But I have to crawl into the attic half a time a day to ventilate there?

Does anyone of you have - meaning insulated floor in the attic + insulation between the rafters?

The construction company also told us that you either make a proper warm roof (tight, warm, controlled ventilation) or a proper cold roof (cold, slightly drafty, insulated only for the warm area), anything in between is basically not possible.

We have had a proper warm roof since ’97 (18cm insulation between rafters; vapor barrier on the room side and covered with drywall boards) and the intermediate ceiling is also insulated (vapor barrier towards the living areas). On the beams there is tongue and groove boarding.

We have a round window in the gable (which is rarely open) and a completely normal hatch with a pull-out staircase (so no Thermos or anything special).

The whole thing was planned by the architect and executed by the construction company.

No moisture problems or mold or whatever have been detected so far.

(But it must be said that the drywall boards have a moisture-regulating effect)