Insulating the garage roof - yes or no?

Hello everyone,

Our double garage has a common wall (filled Poroton) with the house. Otherwise, it is outside the thermal envelope, with insulated separation in the ceiling and in the floor slab. The flat roof of the garage will be greened. Since we want to waterproof the flat roof soon, we are asking ourselves: to insulate or not? The energy consultant says NO because the garage is not within the thermal envelope of the house. The roofer who will waterproof the roof says that most builders in such cases do not insulate and he also sees no necessity... How did you execute the garage roof? What speaks for/against the insulation.

Since the roof is to be/has to be greened, I would of course like to avoid subsequent insulation.

There is plenty of information missing...

Is the garage heated or is it supposed to be heated? If yes, why? (Hobby/workshop room?)
What is the wall structure and insulation of the other walls like? How is the garage door constructed?

The greenery already has some insulating effect, depending on the substrate height. Otherwise, insulation only makes sense if the rest of the garage is also properly insulated and heated.

At our place, the foundation slab for the house and garage was built at the same level. To avoid a step from the house into the garage, we also installed screed and pressure-resistant insulation in the garage. Therefore, it was obvious to insulate the ceiling as well. Garage door Hörmann with LPU 65 mm. Window and exterior door of the garage with triple glazing (like the house). Used as a hobby room or workshop.

there is plenty of information missing...

Is the garage heated or is it supposed to be? If yes, why? (Hobby/workshop room?)
What is the wall construction and insulation of the other walls like? How is the garage door designed.

- Garage is not heated (no workshop, only storage space at the back (approx. 2x6m) for tires, lawn mower, bicycles...
- Sectional door 42mm
- Back door to the garden
- Door garage-hallway aluminum, thermally insulated
- Wall between house and garage (as I already wrote) 36 cm Poroton MZ70 filled with mineral wool.

simple decision. You can apply 100m thick insulation on the roof to achieve an acceptable average thermal transmittance coefficient. But in practice, you are always heating the outside world (if heating), and especially now, one should not do that. Doesn't help either ,_)

If there is no heating, what's the point of insulation? Just get yourself an infrared panel for a future workbench ...