It depends entirely on your specific zoning district's height and story limits for accessory structures, which are often more restrictive than what applies to your main house. We check this first, before any design conversation, since it's a hard yes-or-no gate rather than a design preference.

A second story adds real structural load and wind exposure that a single-story structure doesn't carry, which means the foundation and framing need to be engineered specifically for that — it's a meaningfully different structural problem, not just "more of the same" scaled up.

Second-story windows overlooking a neighboring yard are one of the more common practical concerns with two-story accessory structures, and depending on your jurisdiction's review process, neighbor input can be part of approval. We design window placement and screening with this in mind from the start.

That's typically treated as new detached ADU construction with an accessory garage or flex space beneath it, rather than a garage conversion — the living unit itself is new construction on the second floor, not a repurposed existing garage.

Meaningfully more per square foot, mainly from the additional structural engineering, foundation sizing, and stair construction — it's not simply double the cost of a single-story unit of the same total square footage. We give a project-specific number once feasibility and design are set.

Yes — a code-compliant interior stair typically requires a meaningful, non-negotiable footprint on the ground floor, which is one of the real trade-offs of going vertical instead of building a larger single-story unit if your lot could support either.

Sometimes, if the original foundation and framing were designed to support future vertical expansion — but that has to be planned for from the start. Retrofitting a second story onto a structure not designed for it is a much larger undertaking than building it in from day one.

Often yes, assuming your zoning allows it — building vertically is one of the few ways to get meaningfully more square footage out of a lot that can't support a larger single-story footprint. We evaluate whether your specific lot and zoning actually support that trade-off.