Hire a lawyer; file the proper notice to quit; and file a summary proceeding for eviction. Do not do this without a lawyer; the tenant will lie with impunity about your attempts at self help and "unlivable" conditions. Tenants can place rent in escrow when the apartment is "unlivable." Broken tiles do not make a place unlivable.
On my profile there are several legal guides. I recommend reviewing the following which may be helpful to you:
Hiring a lawyer; Is it Legal? Is it Illegal?...Understanding the different court systems;
Legal terms used in litigation………………………………………………………..
Commercial litigation .
Landlord Tenant Rules and Requirements in General and in New Jersey,
Landlord Tenant Litigation: Eviction, Other Lawsuits in General and in New Jersey
Mr. Sarno is licensed to practice law in NJ and NY. His response here is not legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. Mr. Sarno strongly advises the questioner to confer with an attorney in their own state to acquire more information about this issue.
Check your lease as to what you can do with respect to re-entry to make repairs. Many residential leases will allow the landlord to enter the premises to make repairs when the tenant is not home upon reasonable notice. Even though he is now month to month, the terms of the lease will most likely otherwise still govern.
With respect to the larger issue, if you want him out, you can start an action in Landlord-Tenant court (Superior Court, Special Civil Part) for possession based on non-payment of rent. The turnaround is usually 2-3 weeks or so. A Landlord-Tenant attorney can be of help to you in preparing and filing the papers. Although your tenant could argue that the repairs needed to be done (thus justifying the withholding of rent), the Court can require that he deposit the back rent with the Clerk of the Court pending the outcome of the case. Additionally, the repairs you describe most likely do not rise to a level where withholding the rent is justified.
Likewise, to recover the back rent, you can start an action in the Law Division for the money that is owed through the date of the ejectment. Typically this is a longer process than L/T court. You should definitely consult with an attorney prior to filing this action, as the pleadings and litigation are much more complicated than simple filing an ejectment proceeding in the Special Civil Part.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship. You are strongly advised to contact an attorney to obtain legal advice before taking or refraining from taking any action with respect to the above.
Matthew J. Walters
Law Offices of Gerard A. Walters
20 Vesey Street
New York, New York 10007