You can run a free Grand Junction ADU lot check from your kitchen table in a few minutes, before you pay anyone for drawings. Enter your address, see your property lines and setbacks, and drop real floor plans onto the lot at scale. It won’t give you a permit or a survey. It will tell you whether the spot behind your garage deserves a closer look.
Most talk about ADUs in Grand Junction starts with floor plans. We think that’s backwards. The first question isn’t which plan you like. It’s whether that plan fits your property, and there’s no single minimum lot size that answers it.
How to run a free Grand Junction ADU lot check
Open our free Grand Junction ADU lot check (it runs on ADU Insights) and type in a street address. Then:
- Confirm the parcel that comes up is actually yours.
- Look at the mapped property lines and the setback lines drawn inside them.
- Pick a floor plan and place it on the lot. It’s drawn at real scale, so a plan that looks small in a brochure shows its true footprint.
- Move and rotate it, and watch the live checks for setbacks, size, height and lot coverage.
- Have the preliminary report emailed to you so you have something concrete to bring to a builder.
- Write down what the map can’t answer: where the sewer line runs, how a truck reaches the back, what’s buried under the lawn.
The exercise might tell you your first-choice plan doesn’t fit. That’s good news to get before you spend money on design.
What’s free and what isn’t
The lot check, the live constraint checks, placing floor plans at scale and the emailed preliminary report are free. If you want a downloadable site plan as a PDF or CAD file, that’s a $49 per-property project. You don’t need it to run the lot check, and you don’t need it before you talk with us.
Now the plain part. The lot check is not a survey. It isn’t an engineer’s review, a zoning determination or a permit. It works from public parcel data and published code, and public data has errors. The City of Grand Junction, or Mesa County if that’s your jurisdiction, makes the actual call.
What the tool is checking
Who governs your lot
A Grand Junction mailing address doesn’t mean the City of Grand Junction. Parts of Orchard Mesa, the Redlands and the area around Clifton are unincorporated Mesa County, and there are county pockets surrounded by city. Fruita and Palisade write their own rules. Inside the city, an ADU is capped at 900 square feet of habitable space under Section 21.04.040 of the city code. In unincorporated Mesa County, the maximum size depends on lot size. Same valley, different rulebook. If your parcel turns out to be in the county, the same lot check switches to the Mesa County rules on its own.
Setbacks: drawing the box
Setbacks are how far a building has to stay from each property line. Pull each side of the lot in by its setback, and what’s left is where you’re allowed to build. Inside the city, the numbers come from your zone district’s table in Chapter 21.03, and a detached ADU can use the rear setback for accessory structures. In the RL-4, RL-5 and RM-8 districts, for example, that rear setback is 5 feet.
One wrinkle. The city code says an ADU shall not be located in front of the main house, and another clause in the same chapter talks about ADUs in front yards and corner side yards. Those don’t line up cleanly. If you’re looking at anything other than a plain backyard spot, confirm placement with GJ Planning.
Lot coverage
Every city district caps how much of the lot can be covered. The city’s definition of lot coverage counts roofed structures, pools and structures taller than six feet that are enclosed on three or more sides. Driveways and patios don’t count. On a small lot, coverage can stop a project before setbacks do. Kitchen-table math: add up every roofed footprint, add the ADU you’re picturing, divide by your lot area, and compare that to your district’s limit.
What the map can’t see
Utility easements along the back fence. Irrigation pipes and ditches, which are common on older Grand Valley lots. The sewer line running from your house to the main. A recorded plat or a survey shows some of this. A utility locate and a site visit show the rest.
Access matters too. Older neighborhoods around North Avenue and downtown often have alleys, which make deliveries, the concrete truck and a tenant’s front walk much easier. Without an alley, everything goes through the side yard, past the AC unit and the gas meter. And plenty of ground in the valley has clay soils that move with moisture, so we start with a soils report and an engineered foundation.
A quick example
Say you own an older home with an alley and a deep backyard, and you’ve got your heart set on a wide two-bedroom. On the map, the usable width after setbacks turns out tighter than it looked from the patio. You try a narrower plan, rotate it, and it fits with room left for the shade tree. That’s an afternoon of clicking instead of weeks chasing the wrong design. It doesn’t settle the sewer route or the budget, but it’s a much better place to start.
What to do after your free check
If the lot looks promising, that’s when a builder earns their keep. We walk the site, confirm jurisdiction and zoning, find the utilities, look at access and talk through a real budget. Most Grand Junction ADUs we build are around 900 square feet, and they typically run $160,000 to $275,000 turnkey depending on the lot and the plan. Our Grand Junction ADU cost guide explains what moves that number, and can I build an ADU on my property covers the code side in more depth.
When you have a result and a spot in mind, talk with our team about your lot. You can also browse our plans to see which layouts you’d want to try on the map.
Questions we hear a lot
Is the lot check really free?
Yes. The lot check, live constraint checks, scale floor-plan placement and the emailed preliminary report cost nothing. A downloadable site-plan PDF or CAD file is a $49 per-property project, and it’s optional.
Does it replace a survey or a city approval?
No. It’s a preliminary read from public data and published rules. It isn’t a survey, an engineer’s review, a zoning determination or a permit. The city or county decides, and a surveyor or designer may need to confirm details before you apply.
What’s the minimum lot size for an ADU in Grand Junction?
Inside city limits, the ADU standards don’t set a separate minimum lot size. Your district’s setbacks, coverage and height limits decide what fits. Unincorporated Mesa County is different and its code is under review, which our Mesa County ADU permits post covers.
Reviewed October 2026 by Caleb Blair, founder of God’s Country Development and ICC-licensed general contractor.
