Unpermitted Basement Bathroom Discovered During a Home Sale
A realtor calls you because a buyer's inspector found a basement bathroom in a 1978 house that the seller says was added around 2015 by the previous owner. The city has no permit records for it. The shower drains into a sump pit that discharges to the yard, the lavatory is vented by an air-admittance valve inside a closed vanity cabinet, and the water closet sits on a flange that rocks. The buyer's lender wants assurance the work is legal before closing. The seller wants a letter from you saying the bathroom meets code, and wants the cheapest possible fix.
1. Before quoting anything, how do you sort this into violations, grandfathered conditions, and unknowns?
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Age does not make work legal - only a permit and an inspection do. Sort the findings into three buckets:
- Violations regardless of age: the shower draining to a sump pit that discharges to the yard. A sump pump is not a sewage-disposal method; that discharge is sewage, and it is a health and nuisance problem wherever it lands.
- Dependent on edition and AHJ: the air-admittance valve in a closed vanity. AAVs are allowed in some form in many jurisdictions but generally must be accessible and may not substitute for a vent where one is required. Ask the inspector rather than guessing.
- Unknown until opened or documented: fixture venting, drain slope, whether the water closet flange is broken or just unsecured, and how the group ties to the building drain.
Tell the client in writing which items you can verify, which you cannot, and that unpermitted work cannot be certified as compliant by you.
2. What is the compliance path, and who is allowed to do the work?
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Permit first, never after. File the application with a scope sketch before any repair begins.
Who may perform the work: in Wisconsin, whether an owner may do plumbing on their own property turns on the occupancy - an owner-occupied single-family dwelling is treated differently from a rental or a commercial building - and on local ordinance. Confirm directly with the local plumbing inspector who is permitted to sign, and put that answer in the file.
Inspection sequence: rough-in inspection before anything is concealed, final inspection after. Expect that unpermitted, concealed work means opening the walls the previous owner closed, and price that possibility rather than absorbing it.
Scope: stop the sump discharge, drain the shower and fixtures properly to the building drain, and vent them. A small ejector system is often cheaper than cutting the slab to gain fall, and the inspector may accept it. Get that decision from the AHJ before you buy parts.
3. What goes in your proposal, and what do you tell the seller and the buyer?
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Proposal: state who will obtain the permit, that corrections the inspector requires are additional work, that concealed conditions are excluded, and that you will provide copies of inspection results. Do not promise a compliance letter, and do not sign a statement that the bathroom was legally installed - you did not install it and you cannot certify it.
To the seller: unpermitted work is normally disclosed to a buyer, and some lenders and insurers will require it be permitted, corrected, or removed before closing. Give them the AHJ contact and the option of an inspector review before closing, while there is still time to negotiate.
To the buyer: the discovered defects are known conditions, not opinions - a sewage discharge to the yard is a real problem regardless of paperwork.
Keep every photo, gauge reading, and inspection record. Documentation is the only thing that moves this work from unknown to legal.