A building permit review is a conversation. You submit drawings, the city’s reviewer reads them against the adopted codes and the city’s own amendments, and anything unclear or missing comes back as a written comment. Each round of comments adds time.
The good news is that the questions are predictable. On additions, ADUs, garage conversions and remodels, the same handful of items come up again and again. Here they are, and what to put on the plans so the reviewer doesn’t have to ask.
Existing work that was never permitted
When you apply for new work, the reviewer looks at the whole property. If the city’s records show a garage and your site plan shows a bedroom, expect a comment asking you to bring the existing work into compliance, usually under the building code’s section on violations (IBC 114, or the residential code’s equivalent).
What to do: search the property’s permit history by address before design starts. Show any unpermitted areas on the plans as existing work to be legalized, so they’re reviewed together with the new work. Expect that legalizing may mean opening some finishes so the inspector can see what’s behind them.
Electrical load and the panel
An ADU, an EV charger, a pool or a larger AC unit all add electrical load. Reviewers commonly ask for a load calculation under NEC Article 220 and a panel schedule that lists every circuit, including the new ones.
What to do: get the existing panel’s rating and a photo of the breakers early. If the calculation shows you need a bigger service, ask your city whether that size of service needs a design sealed by an Arizona-registered electrical engineer. Find that out before submittal, not after.
Water supply sizing and plumbing vents
A fixture layout isn’t the whole plumbing plan. For new bathrooms and ADUs especially, reviewers ask for a water-pipe sizing calculation (the plumbing code’s Appendix E method is common) and a riser or isometric diagram showing how each fixture is vented.
What to do: confirm the size of the existing water service and meter. If the ADU tees off the main house line, show the calculation that proves it’s enough.
Heating and cooling calculations
For new homes, additions and ADUs with their own system, many departments ask for ACCA Manual J (the load), Manual S (equipment selection) and Manual D (duct design). A note that says the HVAC is by others usually isn’t accepted.
What to do: run the calculations once the floor plan and window sizes are settled, and make sure the equipment shown on the plans matches the Manual S selection.
The lot itself
Zoning setbacks are only the start. A recorded plat can carry stricter building lines, easements can block an otherwise legal footprint, and many cities want a grading and drainage plan for a new home. HOA rules aren’t enforced by the city, but they can stop a project anyway.
What to do: before design, gather the recorded plat, a title report or list of easements, and the HOA’s architectural guidelines if there is an HOA.
Local amendments
Every Valley city adopts the national codes with its own changes. Garage and outdoor receptacle rules, flood-zone requirements and energy-code options vary from Phoenix to Tempe to Gilbert, and a county island follows the county, not the nearest city.
What to do: look up the amendments for the exact jurisdiction your address sits in, and the code edition it has adopted.
The takeaway
Most plan-check comments aren’t surprises. They’re the same questions, asked for good reasons. A set that answers them up front, with the code analysis, the calculations and the lot research done, gives the reviewer what they need.
We do drafting and permit plans for ADUs and casitas, additions and remodels in Arizona. Every set opens with a code-analysis sheet, and if the city flags an error in our drawings, we fix it free. Ask for a quote.