"Have to" - as in building regulations have to?


If so that's not applicable for garages / places where people are not expected to live in (here in Holland)


If you mean have to in terms of stopping damp from getting in then I don't think that will be a problem. The ground is raised - most of it on some pretty snazzy stuff called "woudzand". This is more like granulated clay than sand and sticks together really well. Whilst it does retain moisture it doesn't really stay all that wet - surface water runs off (most of the time). I've put in two layers of anti-root growing membrane under and on top of the woudzand and the gravel ballast has a depth of at least 20cm. The metal frame sits on top of the railway sleepers which are only slightly set into the gravel. A wooden floor will be fitted on top of the metal frame...


...if I have the funds left over to insulate under the floor only then will I be considering a damp proof membrane for under the floor. Not quite that far yet.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!