Building an ADU in El Cajon
Inland summers are hot. Insulation, window selection, shading and correctly sized heating and cooling make a bigger difference to comfort and running costs in El Cajon than they do near the coast. Ductless mini-split systems are a common choice for ADUs.
Larger lots make detached units easier to place, but long runs for water, sewer and electrical service add cost. Where the ADU sits on the lot is a budget decision as much as a design one.
Permits are handled by the City of El Cajon's Planning and Building divisions. Lots in unincorporated areas nearby, such as parts of Fletcher Hills or Granite Hills, may fall under the County of San Diego instead, so confirm jurisdiction by address.
What state law allows
El Cajon's larger lots make it easier to use everything state ADU law allows. That means one ADU plus one junior ADU on most single-family lots, with a 60-day review for a complete application that meets the rules.
- Converting a garage to an ADU generally does not require you to replace the lost parking spaces.
- Owner-occupancy is no longer required for a standard ADU. A junior ADU still requires the owner to live on the property.
- ADUs under 750 square feet are exempt from impact fees, and units of 500 square feet or less are generally exempt from school fees.
- Detached ADUs typically need only 4-foot side and rear setbacks.
Garage conversion, detached ADU, or both?
A garage conversion keeps the unit close to the house, so water, sewer and electrical runs stay short. It is usually the lower-cost route if the slab and framing are sound and the garage can be insulated well enough for valley summers.
A detached ADU can go where the lot has room, and many El Cajon lots do. The farther it sits from the house and the street, the more trenching and utility work it needs, so placement is worth settling before design goes far.
How an All Pro Contractor ADU project runs
- Site visit to review the garage or yard, access, utilities and the goals for the unit.
- Written estimate covering the scope discussed, with design, engineering and permit responsibilities spelled out.
- Plans and permit submittal, either through our design partners or with plans you already have.
- Construction: foundation or slab work, framing, utilities, insulation, drywall, finishes and final inspection.