Irontown Modular: Prefab ADU Construction in Southern California
Irontown Modular is a contractor specializing in prefabricated Accessory Dwelling Units (ADUs) in Southern California. As an ADU builder focused on modular construction, they work with property owners through every stage of the process — from initial planning and permitting through to final inspection and move-in.
Their approach centers on managing the full scope of an ADU project, which includes budgeting, contracts, planning and permitting, factory fabrication, site construction, and utility connections. By handling these steps under one roof, Irontown Modular aims to reduce the complexity that often comes with building an accessory dwelling unit.
How the ADU Building Process Works
Irontown Modular follows a structured, multi-phase process for each project:
- Planning: A site evaluation is conducted to assess setbacks, accessibility, and utility locations. A conceptual budget is developed covering both ADU construction and site preparation.
- Construction Contract: The budget is finalized and a construction contract is signed before detailed planning begins.
- Plan Design and Submittal: A detailed site plan is created and submitted for approval through state-approved third parties and local authorities.
- Construction: The ADU is fabricated in a factory setting while on-site work — such as foundation and utility preparation — takes place simultaneously. Inspections are coordinated with the local building department throughout.
- Final Inspection: A walkthrough is completed with the client, adjustments are made as needed, and a Certificate of Occupancy is obtained.
One notable aspect of prefab construction is the speed of on-site installation. Because the unit is built off-site in a controlled factory environment, the on-site assembly can often be completed within a single day. This reduces disruption to the property and surrounding area compared to traditional construction methods.
Pricing and What's Included
Detached prefab ADUs from Irontown Modular start at approximately $155,000. This base price typically includes delivery, the foundation system, installation, and utility connections. Additional costs may apply depending on:
- Local jurisdiction requirements
- Special lender requirements
- Décor and finish selections
- Customized options
For properties within city limits such as San Diego, Los Angeles, or Riverside, Irontown Modular also offers Park Model ADUs — sometimes referred to as tiny homes — as an ADU option. These start at around $145,000 and include delivery, installation, and utility connections. Note that title, tax, and registration costs are not included in this price.
Irontown Modular offers a variety of floor plans and customization options, giving property owners some flexibility in choosing a design that fits their needs and budget. They also work with third-party brands for appliances, windows, doors, and finishes, which can influence the overall quality and appearance of the finished unit.
As a detached ADU builder, Irontown Modular serves property owners looking to add a backyard cottage, granny flat, or in-law suite to their property — whether for housing extended family or generating rental income. Adding a two-bedroom ADU can create an additional income stream and may increase overall property value, making it a practical consideration for single-family property owners.
Irontown Modular provides a free project site review to help property owners understand the feasibility of their specific site before committing to a project.