The Top 7 Mistakes New Duplex Owners Make (And How to Avoid Them)
So you just bought or are thinking about buying your first duplex. Congratulations! You’ve officially joined the small-but-mighty club of people who understand that two doors are better than one.
Owning a duplex is an incredible wealth-building tool, but it’s not as simple as “collect rent and live happily ever after.” Here are the seven biggest mistakes I see new duplex owners make — and how you can sidestep them like a pro.
1. Skipping Tenant Screening
Many new landlords are so eager to fill their unit that they skip credit checks, background checks, or income verification. A bad tenant can cost you months of rent, endless stress, and legal headaches, not to mention the cost of turning the unit over once you resume possession. In Minnesota, you can legally ask for proof of income, run a background check, and check rental history. Do it. Every single time.
2. Underestimating Maintenance Costs
That old furnace, leaky roof, or broken garage door? They will eventually need fixing. Too many new owners budget only for the mortgage and forget the “what ifs.” It’s a good practice to set aside a percentage of your monthly rental income for repairs and capital expenses. Ten percent is a good place to start.
3. Being Too “Friendly” with Tenants
This is a mistake I’ve made all too often. It’s easy to blur lines when it comes to tenants. If they become your friend, then stop paying rent, it’s much, much harder to file for an eviction. A good rule of thumb is to be friendly but professional. Use email or text for maintenance requests and notices so you have a written record, and set boundaries just like you would with any other rental.
4. Ignoring Local Codes and Permits
Adding a washer/dryer or remodeling the kitchen without pulling a permit? Not only could you face fines, but it might also mess with your insurance. Adding a unit? Check with every department in your local municipality and get it in writing that you have their permission. Adding one that is non-conforming will not only cost a lot of money to build, but even more if the city requires you to take it out.
5. Not Treating It Like a Business
A duplex isn’t just your home — it’s also an investment. That means keeping detailed records, having a separate bank account, and tracking every deductible expense. Create a simple spreadsheet or use landlord software. (I find Stessa very user friendly.) At tax time, you’ll be glad you did.
6. Setting Rent Too Low (or Too High)
Price it too low, and you’re leaving money on the table. And if you’re in a rent controlled city, you won’t make up the difference for years. Price it too high, and you’ll face long vacancies. Holding out for $100 more a month in rent will take you 15 months to recoup the $1500 you lost while you were waiting. Research current neighborhood rents (sites like Rentometer or local Zillow or Facebook Marketplace data can help). Also factor in amenities like parking, laundry, and garage space — they add real value.
7. Forgetting the Power of Cash Flow
New duplex owners often just “hope the rent covers the mortgage.” That’s not enough. You need money for repairs, vacancies, and — oh yeah — profit.
While it’s nearly impossible to have the rent from the other unit cover all this without you having to pay rent, run the numbers. A good duplex should not only cover your mortgage but also leave money left over each month.
Final Thoughts: Avoid the Pitfalls, Reap the Rewards
Buying a duplex is one of the smartest financial moves you can make. But like any business, success depends on avoiding common mistakes. Screen your tenants, plan for expenses, respect local laws, and treat your duplex like the mini-business it is. Do that, and your duplex won’t just be a roof over your head — it’ll be a wealth-building machine.
If you’re ready to take that step, give me a call. There are few things more rewarding than helping someone start on the path to building long-term wealth.