Whoa, the only thing that strict here are the construction regs.! All building plans from I don't know when are filed at the Construction police department. We went there and had no problems getting the original plans for our 1913 house (except for having to pay $11 and very expensive copies).
Not even gas lines are checked that much here. A plumber has to install them, when the rough-in is completed he calls the gas company for a first inspection, then you can plaster the holes in the walls. This inspection includes a thorough visual inspection of all pipework and a soundness test (done with quite a weird instrument which looks like a large freestanding bycicle pump with a clear vertical plastic pipe. The pipe is filled with water to nearly overflowing and twice the usual pressure is pumped into the pipework. If the water level drops over five minutes the lines aren't tight) When everything is finished, appliances are connected the gas co. guys come and hook up the meter. About half a year later the final visual inspection comes. This guy check's for example whether you have the required vent cutouts in the bathroom door if a boiler is installed in there (quite a sad feeling to cut holes into old panel doors).
However, there are no plans of the pipework, only a list of which appliances are connected to the supply. Whenever any pipework is added or altered rough-in and final inspection have to be done again.
Plus you have to have a chimney soundness certificate signed by your chimney sweep prior to installing any gas appliances (direct vent into the room or venting to the outside air is prohibited, ALL gas appliances have to be connected to a chimney, not like in Belgium or France where direct-vent 5l boilers are still used, or like the UK where venting through outside walls seems to be quite common)
Sorry for the halfways off-topic post.
