Red Flags When Buying a House
Some of what worries buyers at a showing is nothing. Some of what they shrug at should stop the deal. Here is how I sort the two.
By Vito LiRosi · Realtor and licensed home inspector · September 2026
Red flags when buying a house, sorted the way an inspector sorts them.
Most red flags when buying a house are not deal breakers. The job is not spotting problems, it is sorting them into three piles before you negotiate.
- Structure, water and safety go in the first pile. Everything else is a number somebody will put in writing.
- A pattern beats a single defect. One sticking door is a door. Four along the same wall is a framing question.
- Concealment is its own red flag. A covered problem also tells you what the seller will do about the parts you cannot see.
- The worst one is refused access. A seller who will not let a trade look at something is answering the question for you.
Most lists of red flags when buying a house are written by people who have never been under one. They tell you to watch for cracks. Every house in the Northwest suburbs has cracks. Nobody tells you which crack means soil is pushing a wall inward and which one means the concrete cured in August.
I see the same house twice. Once as the agent walking you through it, and once as the licensed home inspector who would have to open the mechanical closet. This post is the second version: the triage I run in my head at a showing, and the order I run it in.
The three questions that turn a red flag into a decision
Before you sort anything, run three questions. They do more work than any checklist.
Is it water? Water is the only defect that keeps working while you sleep. A dry crack and a damp crack are two different purchases. Everything else on a wish list waits for you. Water does not.
Is it a pattern or a one-off? One door that sticks is a door. Four doors that stick along the same interior wall is a framing conversation. One stained ceiling tile is a repaired leak. Three in a line under the same bathroom is a leak that is still running.
Was somebody hiding it? A problem left in the open is a repair. The same problem behind fresh paint is a repair plus a seller you now cannot trust on anything you did not personally look at.
If you have not walked the house yet, my guide to what to look for when buying a house covers the order I walk it in. This one picks up at the moment something makes you stop.
Deal breaker, negotiate, or ignore
Everything I find lands in one of three piles. Structure, water and safety go left. Anything a licensed trade will put a written number on goes in the middle. Taste goes right, and taste is where buyers waste most of their negotiating room.
| What you are looking at | What it usually means | Which pile |
|---|---|---|
| Horizontal crack across a foundation wall | Lateral pressure from soil, not ordinary settling | Deal breaker until a structural engineer says otherwise |
| Floors sloping toward one interior wall | Something below that wall was removed, cut, or was never sized for the load | Deal breaker until the framing is opened up |
| One basement corner freshly painted, the rest not | A stain was covered rather than a source fixed | Deal breaker until you know the source |
| Seller will not allow the sewer line to be scoped | Unknown, and the unknown is the part that costs | Deal breaker |
| Active staining on the ceiling below a bathroom | A leak that is happening now, not one that happened | Negotiate, after a plumber opens it |
| Knob-and-tube or aluminum branch wiring | A safety issue and, separately, friction with insurers and lenders | Negotiate, with an electrician’s written scope |
| An electrical panel your inspector flags on sight | Breakers that may not do their one job under load | Negotiate, replacement is a defined piece of work |
| Cupped shingles, bare granules in the gutters | The roof is at the end of its service life | Negotiate, roofs are easy to quote |
| Finished basement with no permit on file at the village | Unknown wiring and framing behind finished walls | Depends on what the village record shows |
| Dated kitchen, worn carpet, bad paint colors | Nothing at all | Ignore |
Structure, water and safety go left. Anything with a written quote goes in the middle. Taste goes right.
Buyers get this backwards in a predictable way. They fall in love with a house and quietly downgrade a foundation crack into the middle pile, then spend their negotiating room on a kitchen they were going to redo anyway. Sort first, negotiate second.
The cover-up tells
These are not proof of anything. They are each a reason to look behind the thing.
- Candles or plug-in fresheners concentrated in one room while the rest of the house has none. Smell is the cheapest thing in the world to mask and the hardest to fix.
- One wall or one corner painted a slightly different white than the other three.
- A rug in a spot no one would put a rug, or storage stacked flat against a single basement wall.
- A dehumidifier running in a basement the listing calls dry.
- A brand new sump pump in a house where nothing else is new.
Ask about any of them out loud. The answer matters less than how quickly it arrives.
The red flags that are not inside the house
Some of the worst ones never appear in an inspection report, because they are not in the building.
Walk the block. Four for-sale signs inside two blocks is worth a question. So is a street that is quietly turning over to rentals, which changes who your neighbors are and how the block is maintained. Look at where the lot sits relative to everything around it: the low corner of a subdivision collects what the high corners shed, and the FEMA Flood Map Service Center will tell you in about a minute whether you are near a mapped flood zone.
Radon belongs on this list too, since it is a regional condition rather than a defect in the house, and a standard inspection does not include it. The EPA radon zone map is the place to start.
Then call the village. Pending road work, a rezoning application on the parcel behind the yard, or an open permit on the house itself are all public and all free to ask about. None of these show up at a showing.
What the Illinois paperwork does and does not tell you
Illinois sellers complete a Residential Real Property Disclosure Report, a fixed set of yes-or-no questions about defects they know of, defined under 765 ILCS 77. Read it, and read it for what it is. It records what a seller says they know. It is not an inspection, it is not a warranty, and a box left unchecked is not the same as a defect that does not exist.
Two other things live in that stack. If the house was built before 1978, federal rules require a lead-based paint disclosure, described by the EPA, and a great deal of our post-war housing stock qualifies. And a listing marked sold as-is describes the seller’s posture on making repairs. It does not erase your inspection.
Unpermitted work is the one I chase hardest around here. A finished basement or a rear addition from the 1960s or 70s with nothing in the village file means the wiring and the framing behind that drywall were never looked at by anyone. That red flag lives in a filing cabinet, not in the house. I am not an attorney and none of this is legal advice; in Illinois you will have one, and the disclosure questions belong to them.
The red flag almost everyone talks themselves out of
A seller who limits access. Will not move the storage off the wall. Will not allow the sewer scoped. Schedules an inspection window too short to finish in. Buyers are polite about this because they want the house, and because refusing access does not feel like a defect. It is the loudest one on the list. Somebody is telling you about a part of the house you have not seen, and it is the only red flag I have never regretted walking away from.
What to do the minute you find one
The sequence matters more than the finding.
Do not negotiate off the inspection report. An inspector’s job is to find and describe, not to price, and a general report is the weakest document you can bring to a seller. Get the specific trade out to look at the specific thing, and get their scope in writing before your contingency date passes. Watch that date. It is the only real bargaining power you have, and it expires quietly.
Then decide on the written number rather than on the feeling in the room, and remember which pile the thing was in when you started. A first-pile item does not become a middle-pile item because a quote came back lower than you feared. If you want the detail on what gets examined once you are under contract, my home inspection checklist for buyers walks through it system by system.
And a house you walk away from is not a loss. It is a house that did not cost you anything.
Red flags when buying a house only matter if they change what you do next. Sorted properly, most of them turn into a written quote and a credit. A few of them turn into a different house. If you want someone in the room who reads a basement wall the same way he reads a contract, that is the point of working with a buyer’s agent who inspects houses for a living.
Not sure whether what you found is a problem
Send me a photo and the address. I will tell you which pile it belongs in before you spend money on a specialist, and I will tell you straight if the answer is walk away.
Ask Vito About a HouseGeneral information for Northwest suburban buyers, not legal advice. Conditions vary house to house.
