ᐅ Floor Structure for Garage/Workshop

Hello,
I am currently planning the renovation of a rather poorly insulated garage into a small hobby and motorcycle workshop...

Since I have now received three different recommendations for the floor construction from three self-proclaimed "experts," I am a bit confused. That’s why I am turning to you.

Floor requirements:
- Insulating effect against cold from the ground
- Approximately 170-180 mm (7-7 inches) increase in the existing floor level
- Still occasionally usable as a garage (only very rarely, 2-3 times per year, but then with a heavy vehicle (~2.5 tons))
- Only occasional heating by a wood stove
- The usual challenge: “As economical as possible”
- Impact sound insulation not required / irrelevant

Current situation:
- Garage is part of a former stable section of our house (built in 1919)
- Concrete floor, cold, about 170 mm (7 inches) lower than the garage exit, unevenness up to 30 mm (1 inch)

Planned floor construction so far:
- Edge strips along the walls
- Lay down a polyethylene (PE) vapor barrier sheet
- About 50 mm (2 inches) of wet screed to level out the unevenness
- Vapor-proof membrane
- 100 mm (or possibly 2 layers of 50 mm (2 inches)) high-compressive-load rigid foam insulation (e.g., extruded polystyrene)
- 22 mm (just under 1 inch) OSB boards
- PVC floor covering

Is this approach feasible? Am I overlooking something?
Is such a setup achievable at around €30 per square meter (currently saved for this; if not enough, I will simply save more)?

Thank you very much in advance!

Best regards

Oh yes, I almost forgot. The highest point load will probably come later from the two planned moped lifts. With a moped on them, they weigh about 150 kg (330 lbs) and rest on four small castors.

Best regards, Platti

Is it common to insulate the floor of a garage?
When it’s below freezing outside, you’d want to keep the few degrees of warmth from the ground, right?

That would make the floor construction much simpler and more cost-effective.
I would only insulate the ceiling and walls, and actually do it better there. Because of the garage doors, you don’t really need to overdo it there either.
Is your main goal to be able to work in the garage during winter?
With a decent wood stove, a garage like that warms up in about 5 minutes and is probably more economical over many years.

Hello

I have some concerns that the load from the vehicle might not be properly distributed by the OSB boards, and the small wheels could potentially damage the PVC. However, it is certainly a "warm" solution.

Olli