How to Visualize a Garage Conversion Before You Build

A garage holding a lawnmower and a decade of boxes is also the cheapest square footage in most houses to turn into something that earns its keep — a home office, a gym, a guest suite, a rentable studio. Before anyone calls a contractor, they want to see the door gone and the wall filled in, not picture it. Here's how to get there from one photo in a few minutes, and exactly where the result stops being something you can build from.

Step 1: Shoot the garage door straight-on, then the inside

• Photograph the exterior elevation with the garage door straight-on if you can — the tool reads the opening it has to fill in and the siding it has to match more reliably from a flat angle than a steep one.
• Get enough of the wall on either side of the door in frame for new siding or a window to read as tied into the existing wall, not floating in isolation.
• Photograph the inside with the door down and the space empty, or as empty as it is now — clutter in frame can get redrawn into something else rather than simply removed.
• A phone photo is enough for both shots — no site plan or survey needed to start.

Step 2: Close up the opening on the outside

Upload the exterior photo to Exterior AI and write the prompt as the specific change: "replace the garage door with a wall section matching the existing stucco siding, add a single window centered in the new wall, keep the roofline and trim unchanged." Leave Structure Lock off here — it defaults off on Exterior AI specifically because filling in a door opening is a change to the massing, not just the materials. Each run is 100 credits.

Step 3: Finish the inside as the room it's becoming

Upload the interior shot to Interior AI and pick the closest room type to what you're converting it into — Home Office, Home Gym, Home Theater, and Family Room are all in the 22-option dropdown — or write your own room description if none of them fit. Describe the finish directly: "drywall and paint over the exposed studs, engineered wood flooring over the slab, recessed lighting, a window where the garage door was." Leave Structure Lock off, since turning a raw garage into a finished room is exactly the kind of change it's designed to allow. Each run is 100 credits.

Step 4: Working from a sketch instead

If you've already sketched the new elevation — the window placement, a dormer, or a small bump-out to clear headroom — run that sketch through Sketch to Image with Structure Lock on. It's designed to hold the lines you drew rather than reinterpret them, which matters here if you've already settled on where the window goes and don't want the tool proposing its own layout.

Step 5: Compare directions before anyone picks up a hammer

At 100–100 credits a run, it's cheaper to run the exterior with a window and without one, or the inside as an office versus a gym, than to repaint a wall and decide you don't like it. Run the exterior and interior separately — each one is a smaller, more specific change for the tool to make than asking for both in one prompt.

Where this is not enough

A garage conversion is one of the more heavily regulated small renovations — be clear about what the image is before anyone relies on it for a decision that costs money.

• It's a presentation visual, not a permit drawing. Turning a garage into habitable space usually means insulation, a continuous foundation or slab assessment, an extended HVAC run, and — in most jurisdictions — an egress window of a specific minimum size in any room used as a bedroom. None of that is checked or shown here.
• Zoning and parking rules vary by city and sometimes by HOA — some jurisdictions require replacing the lost parking elsewhere on the lot, and treat an attached conversion differently from a detached one. Check with your local planning department before you commit to a design.
• It redraws the whole frame, including what you didn't mention. Expect siding texture, shadow lines, or the driveway in front of the old door to shift slightly even when the prompt only asked for the door itself — compare the result against the original before you call it final.
• For a measured, exportable 3D model of the finished space — one you can section, dimension, and hand to a contractor for pricing — model it in Design Studio instead, included with every account. If the conversion is meant to be a legally separate unit rather than a bonus room tied into the house, ADU rendering and floor plans covers that distinction and the full plan-to-3D workflow for it.