The craft of the roofers and zinc workers who work on constructing and maintaining the city's rooftops has been included in the French Culture Ministry's list of intangible cultural heritage
I suspect it could be BOTH!!!
i.e "Intangible" for the skills of the workers and "Tangible" for the resulting rooflines etc! The latest link provided by Durian on Aug 2 2017 above certainly seems to be about the "Intangible" but the earlier links from Aug 2016 seem to definitely be about "tangible" matters
Probably needs a bit more investigation to firm up on this - but the demise of the Nomination Web link some time during the past year might indicate that the idea of a "tangible" nomination has been dropped and that the effort is to be concentrated on the intanbible"?
Re your q - I don't think that the "Intangible heritage" scheme has a "Tentative List" in its procedures - but I may be wrong. See -https://ich.unesco.org/en/lists