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Property owners in Centennial often overlook one of the easiest ways to add income: the space they already own but rarely use. A detached garage collecting dust, or a basement that's been storage for years, sits on plenty of lots across this part of Colorado without earning a cent. At today's prices, a second investment property is simply out of reach for a lot of owners in this market.
Building a legal unit on land already owned skips that expense while still creating a second stream of rent, something we've seen work well when owners approach it with a plan for setting a strong rental foundation from the very beginning.
Key Takeaways
- A second unit lets Centennial owners add rental income without purchasing more land.
- Colorado's zoning flexibility has made adding a second unit more approachable for many homeowners.
- A well-placed second unit tends to raise both monthly income and long-term resale value.
- Reviewing financing, upkeep, and screening details early helps owners avoid costly setup mistakes.
The Space That's Already Costing You Money
Most properties in this area hold at least one section producing nothing useful, and recognizing it is the first step toward turning it into income.
- A detached garage that hasn't held a car in years.
- An unfinished basement collecting boxes and old furniture.
- A bonus room that only gets used a few times a year.
Turning any of these into a legal rental generally means adding a private entrance, kitchen, and bathroom so the space functions as its own unit, then confirming the layout meets current city and county standards before construction starts.
One owner near Highlands Ranch had a detached garage that hadn't held a vehicle in over a decade. She added a kitchenette and separated the entrance from the main house, and leased it within a month, picking up several hundred dollars in added monthly income without touching her lot size.
Local Approval Is More Predictable Than It Used To Be
Colorado municipalities have clarified their rules around accessory units in recent years, which shortens the distance between planning a build and actually collecting rent from it. Local contractors have grown more familiar with these builds as demand has climbed, part of why nearly 1 in 5 residential units produced today in ADU-friendly states is a second unit like this one. Owners aren't navigating unfamiliar territory the way they might have a decade ago.
Placement Still Shapes the Rent
Not every neighborhood carries the same rental demand, so where the unit sits on the lot still matters even within a single city.
Factors Worth Weighing
Proximity to schools and major employers tends to support higher rent, and lot shape often determines whether a garage conversion or a detached structure makes more sense. Owners weighing that decision often lean on our residential guarantee coverage already protecting the main house, and extending that same standard to a second unit tends to protect the investment from day one.
What a Second Unit Does to Resale Value
Beyond the added rent, a second unit tends to raise what the whole property is worth to a future buyer. Appraisers in this region have reported a pattern similar to what federal data shows nationally, where the median appraised value for properties with an accessory dwelling unit reached $1,064,000 in 2023, notably higher than comparable properties without one. That's a meaningful cushion for owners thinking about resale, in addition to the monthly rent.
Financial Details Owners Often Miss
A few surprises tend to show up once owners run real numbers on a second unit rather than rough estimates.
- Financing usually comes from home equity, a construction loan, or a cash-out refinance, and each carries different repayment terms.
- Rental income from the unit is taxable, so depreciation, insurance, and maintenance need their own paper trail apart from the main house.
- Utilities, landscaping, and repairs for the new unit add ongoing costs that belong in the rent calculation from day one.
Choosing finishes that hold up under regular use matters here too, since renovations built to last tend to protect the return far better than upgrades chosen purely for appearance.
Filling the New Unit With the Right Tenant
A finished second unit only earns money once it's leased, and that part isn't automatic. Owners sometimes assume the same marketing that filled their main house will work the same way for a smaller, standalone space, and it often doesn't.
A surge of inquiries right after posting a listing can feel promising, but the conversion gap in listings shows up when volume doesn't translate into qualified applicants. Adjusting the listing to fit the smaller unit's actual audience tends to bring in serious renters far faster.
Two Units Bring Two Sets of Landlord Responsibilities
Adding a unit means adding a second tenant relationship and a second list of ongoing concerns, not just a second rent check.
- A separate lease apart from whatever agreement covers the main house.
- A full round of screening, since background and rental history checks apply regardless of unit size.
- A second set of maintenance requests, since repairs now cover two structures instead of one.
Owners who've moved toward rent payments that make sense for their main house tend to apply the same structured approach to the second unit, which keeps both income streams easier to manage side by side. One owner assumed the tenant pool that worked for his main house would work for the second unit too, and it sat vacant longer than he expected until he adjusted his approach to fit a smaller, standalone rental.
Deciding If This Fits Your Property
Start with what you actually want from the property before committing to a design. Steady, higher monthly income without buying another home is worth serious consideration for a lot of owners in this market. A free rental analysis gives realistic rent expectations based on comparable properties nearby, which helps settle the question before any money goes toward plans.
Where to Find More Guidance Before Building
Owners considering this step often have questions that go beyond rent projections, from zoning specifics to how a second tenant affects insurance coverage. Our owner resources page covers many of these topics in more depth, giving owners a starting point before they commit to a contractor.
FAQs about ADUs as a Rental Income Strategy in Centennial, CO
Does Colorado's elevation and climate affect construction timelines for a second unit?
Yes, exterior work often pauses during heavy snow months, which can extend a project timeline compared to milder regions. Planning around a warm-weather construction window keeps expectations realistic.
Can a second unit be built above an existing garage instead of beside it?
Often yes, provided the existing structure can support the added weight and meets current building codes. An engineer's assessment early on confirms whether the foundation can handle the addition.
Do HOA rules in this area typically restrict accessory units?
Some communities have restrictions written into their covenants, so checking with the HOA before finalizing plans avoids a costly redesign. Not every neighborhood in the metro area allows them.
How does a second unit affect snow removal responsibilities on the property?
Most owners handle snow removal for both structures themselves or through a shared service. Clarifying this in each lease avoids confusion once winter weather actually arrives.
What happens to permits if I sell the property before construction finishes?
Permits typically transfer with the property, though the new owner usually needs to complete any required inspections. Disclosing the project's status during a sale keeps the transaction straightforward.
What Started as a Storage Room Now Pays a Mortgage
A garage that once held nothing but boxes can end up covering a real chunk of a mortgage payment once it's leased, and that shift tends to happen faster than owners expect. PMI Cherry Creek stays involved at every stage, from the first permitting conversation through the day a tenant moves in, so the project keeps advancing instead of stalling between steps. Find out what your property could earn with a second unit added to the mix.
