Report Landlord/House Not Registered

The RTB registry is not always updated so can sometimes be hard to find a registered property.

The RTB registry is indeed not always updated, and the site as of now is an utter disaster (everyone gets charged a fine which will be refunded, as is the RTB itself). Older landlords can be cash only as that's how they always did things, and banks nowadays can be hard for older people. If they don't report their earning accurately, they paint a target on their backs as Revenue prefer smaller targets like them, not NAMA builder moghuls.

Did you try having a quiet word with the tenants?

The RTB are fcuking useless, even when they take a case, A 3rd party dispute should be the way to go, BUT if the landlord isn't registered and therefore has not provided details, the RTB will say, "we dont have their details cant do anything" even if they do have an address, if the landlord fails to respond, they can say "the landlord did not reply" and refuse to take a 3rd party case against them. That alone makes me think the rtb are bordering on useless, because they will try fob you off. Record all calls (if only for your own record to write down later) with them but dont highlight that, ie use a second phone or a dictaphone.

Although I have had taken 2 cases to the rtb, from my experience, the rtb barely want to be involved even when it gets to that stage and can be partial towards tenants. OP I suggest you gather evidence, make a log of events in writing, take some photographic evidence, (cross reference both, ie if there was noise at a set time, discreetly take a picture of what cars were there), on that point record car details and reg/number of vehicles, keep doorbell footage (less in someones face and obvious than an actual security camera as lots of people have them), Ring makes you pay to keep records, but it's not much and well worth it imo.

Record noise, but note phones are not great at recording noise in my experience, due to signal noise in the mic, phones just arent up to scratch for a lot of recording, they just do the basics. Personally I wouldnt go out of my way to report someone if the tenants were reasonable, but once I read they aren't reasonable, then I'd go all out. The rtb register can be slightly out of date, but its a good start,and a lot of the time it is updated and accurate, limit your search terms, ie dont put too many in or be too specific, because some people record their property details woefully inaccurately, not sure if that is because they dont care, trying to hide something or just thick. Address may be slightly off, search under different stuff seperately, ie for street name and see what turns up, without including the actual house number. I'd also suggest looking up the landregistry to see who the owner is, that will provide you their name at least.

You can get the name of the current property owner, who would be the de facto landlord even if they use an agent to manage their rental property. You'd have to pay a few euro for a copy of the folio, though.

Revenue will have a keen interest. Might be worthwhile giving them a call

Is it not that all tenancies have to be registered with RTB, including RAS? To claim mortgage interest Revenue insist the tenancy is registered with RTB. Revenue don't care if its private or social letting, just that it's registered.

Revenue are the ones with the real power and enforcement

Lots of assumptions here. You in fact know nothing about this landlord but want cause him trouble because you dont like his tenants. The landlord you are saying is responsible for his tenants behaviour and thats another matter.