I have no hostel but plan to open one next year, near Fontainebleau, for boulderers/climbers(especially foreign climbers), hikers, visiting backpackers...
I think the French regulations can be managed if you think ahead and meet the right persons who will help you.
Basic regulations in France:
A hostel is classified as ERP (etablissement recevant du public); 5th category if less than a capacity of 100. That means safety/security and disabled access regulations.
Best solution: a flat building, all rooms with direct outside access: no complex alarm system required
Medium solution: ground floor + first floor; no smoke evacuation, no need to separate the staircase
In all cases, one staff member has to be on site 24/24 (really on site)
Be carefull about electricity: drawings have to be checked by a third party (like Veritas) before professionnal installation.
Be carefull about materials you use: they have to be fire safe.
The kitchen power has to stay under 20 KW; above they are other security regulations.
My suggestion: work with an architect with proven experienced in ERP's
Disabled: you have to provide access to disabled: one or two rooms (depends on capacity) and ALL common areas; my advise: go a little bit further, ask for the "tourisme and handicap" label ... and get the related subsidies which cover the additionnal costs.
Before opening, a special security commmission will visit; they report to the mayor who gives the authorisation to open.
Get confirmation of all my informations: the firefighters (SDIS) will help you; meet them and bring drawings etc. The CDT (comite du tourisme) will help you for disabled access (and help you to get subsidies).
Another general advise would be to present yourself as "gite d'etape" if you are near a hiking trail (GR trail), this category is well known and promoted. Go meet the local mayors: in my case, the municipality will probably buy the building and rent it to me, which makes it easier from the financial side...
I hope this can help !
Does someone have other informations about opening a hostel in France ?