State laws vary - so check yours first - i'd suggest a sit down with a real estate lawyer.
In my state:
First there is always a timeline - ours is 60 days for residential - 90 for commericlal.
1. Call the assessors office, get the OWNERS (the person that ordered the service is not always the owner) legal name - and the property's LEGAL address - the legal addy is usually different than the mailing addy. Does not matter if the owner ordered services - the proprty benefits from the service - in turn the owner is responsible.
2. Get the mechanics lien or property lien form YOUR state uses. Enter the peritnent info.
3. Our state requires formal notification ten days befroe the lien is filed as a last chance to pay deal.
4. Notarize and file (only for the face value of the debt - you add your legal penalties, costs, interest after the fact to satisfy the lien or it can be fought and invalidated in court) with the proper state or county deparment.
5. In our state, once the lien is filed - the debtor is usually (by state law) responsible for all legal costs, so now is the time to get a lawyer involved to send that demand payment letter, though they (lawyers) want paid now - you'll be able to recoup it when payment comes to satify the debt.
6. In my state - you can foreclose on a lien for any amount. And written in the demand letter - if legal in your state - usually gets attention and payment really really fast.
Unfortunately, if you foreclose, and they are upside down or have no equity, the primary mortgage holder gets paid (or in some cases if they stand to take a loss could pony up the funds) first and you get squat. What I do in that situation is look at it as my retirement fund. We can collect interest, I currently have this exact situation ongoing, and the homeowner being cute, knows it - but what they don't realize is that in ten years... they will have equity, and when I cash in my chips, they can pay me about 4.5 times the debt - which will have grown to over 20k - or find a spot under the bridge.
And to be honest - I could care less - we did a water loss - he got the check, and spent it. In fact, when we were putting the final touches on the resconstruct for the loss - a new plasma tv was being installed in the basement....hmmmm.
I have about a dozen of them that I'll cash in when the time is right - all the same case - HO took the insurance check and ran - we even offered no interest 3 yr payment options just to avoid the hardline tactics we could emply - trying to be the nice guy just to get paid - they chose the hard road and will pay for it dearly in the end - I have no sympathy for shysters who steal my services.
And this is something that is exploding - I recently read that lien filings in most states have risen nearly 1000% so far this year.