How Are Denver Alley-Garage ADUs Designed and Permitted?

The feasibility study answers this before design begins. The engineer exposes the foundation at several points to measure footing width and depth, checks the slab for thickness and reinforcement, and looks for settlement, frost heave, or water damage. Garage framing gets the same scrutiny: wall studs, top plates, rafters or trusses, and the diaphragm that may or may not exist. The findings sort the project into one of three paths - reuse with reinforcement, partial rebuild, or full replacement - and each path has a very different budget. Reuse with reinforcement is the sweet spot when the bones are sound: new shear walls or steel frames for lateral loads, sistered or replaced framing members, a structural floor over the slab, and upgraded anchor bolts tying walls to the foundation. The engineer designs the connections - hold-downs, straps, and diaphragm nailing - that turn a car shelter into a dwelling the code recognizes. Where the foundation is inadequate, underpinning or a new foundation is designed before any vertical construction, because everything above depends on it.

Zoning compliance is drawn, not assumed. The site plan shows the ADU against every applicable setback - from the alley, the side and rear lot lines - plus height, lot coverage, and any bulk-plane or view protections the zone district imposes. Parking and owner-occupancy rules are verified in writing, since they vary across Denver's zone districts and overlays. Getting this right on paper prevents the most expensive kind of surprise: a designed project the zoning reviewer cannot approve. Fire separation follows from the site geometry: walls near property lines and the alley get the fire-resistance ratings and opening protections the code assigns by distance, detailed so the contractor can actually build them. Utilities are verified, not assumed - the sewer lateral is camera-checked for depth, condition, and capacity; water, gas, and electrical services are sized for the added dwelling load. The permit set coordinates structural, architectural, and utility work in one package so each reviewer sees a complete project.