almost four years old, ten answers, and not one single English-native source offered.
all references to experience, and 'yes, use it all the time', are useless when deciding whether this is worthy of inclusion in a dictionary or not. All that counts are linkable source references where it is clear that the suggestion means what it is supposed to mean; that the meaning is the same for the equivalent term in the other language; and best if both come from dictionaries worth the name.
The link in #9 is in English, but the company is a German one.
at the moment Google coughs up 20 hits for site:.uk, of which only one is from companies registered in England, respectively an official site:
In Northern Ireland goods may be delivered franco domicile as for the rest of the
and this text originated in 1948.
for BE at least this is dated, rare, perhaps even obsolete.
If it is widely used in Großanlagenbau, as #10 suggests, then it is rather surprising that it doesn't show up more in Google, but this might be explained by the fact that those other hits for site:.uk in English that use the term are all Germans - perhaps this is a usual German translation for Frei Haus. If this is the case, then it should be marked: Jargon
As mm has commented, in #8 - supportable if properly flagged. And I agree that this term appears to be: more common in the English papers of German companies than in the English papers of English companies, indicating that these companies are using a common source that is not quite up to date.
Amazon.co.uk turns up in the Google search above, but the content is the return terms of a company in Germany:
our official clearance number and should be shipped franco domicile: XXXX Music Entertainment GmbH, Bayernstrhttp://www.amazon.co.uk/gp/help/seller/return...