Can you build a mother-in-law suite on your lot? Check your address

Diagram showing internal, attached and detached ADUs — The three arrangements, on the same lot

First, the basics

You've probably heard it called something else

Mother-in-law suite, granny flat, casita, carriage house, in-law apartment — all the same thing. Builders and city planners call it an ADU, short for accessory dwelling unit.

Whatever you call it: a small second home on your lot, with its own front door, kitchen and bathroom.

Three ways to build one

A basement apartment

Your lower floor made into a private unit. The cheapest route, and nothing changes outside.

An addition on the side

Attached to your house but with its own entrance and kitchen.

A cottage out back

A standalone little house in the garden. The most private, and it rents for the most.

How this works

How it works

Put in your address

We look it up in the county record.

You get your score

Out of 100, with the size that fits and anything standing in the way.

We ring you once

What it would cost, and what it could rent for.

Your property

Your home will show up here

Put your address in — tap to start

Property found

Your score is ready.

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Your score shows up on this page as soon as you press the button. No waiting on an email.

The score is free
Your details stay with JJ28 — we never sell them on
No obligation, and no cost for the check

Checking your property

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Why owners do it

Leveraging what you already own

The land is already yours. Most owners leverage the equity in their home to fund the build, and the unit earns from the day it is finished.

Build passive income

A finished unit rents like any other small place nearby, and that rent comes in against a mortgage you're already paying. It's an income property that happens to be behind your house.

Worth more when you sell

Every square foot you add is equity, on land you already own. And a house with a second, rentable home on it is a rarer thing to put on the market than a house with a new kitchen.

A place for friends and family

A parent who shouldn't be on their own. A kid who can't afford Denver. Near enough to help, far enough that everyone keeps their privacy — and you still own the building after.

Who you'd be working with

A Denver contractor, not a lead broker.

JJ28 Construction & Design has been building in Denver for over ten years — basements, kitchens, framing, foundations, and ADUs. Family run, locally owned, and the same people who answer the phone are the ones on your site.

10+years building

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Permitted and code-compliantZoning checks, permit sets, utility tie-ins and energy code — handled, not left with you.

Nothing handed offFoundations, framing, drywall, kitchens, baths — our own crews, not a job passed to someone else.

Financing, design and buildOne team from the first conversation to the final inspection — funding options, drawings, permits and construction.

Find out what your lot can take

A lot of people around Denver don't know the law changed, or that their own lot might already qualify. Ten seconds will tell you. If it turns out not to suit, that's worth knowing too.

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