Pre-Fab ADUs: Faster Timeline, Same Quality
Factory-built ADU modules delivered and installed on your property. 8-12 week timelines vs 4-6 months for custom builds — with the same code compliance and permitting.
How Pre-Fab ADUs Work
Pre-fabricated ADUs are built in a factory-controlled environment, then transported to your property and installed on a prepared foundation. While the unit is being manufactured (8-12 weeks), we prepare your site — foundation, utility trenching, and connections — so everything is ready when the unit arrives.
The result is a shorter overall timeline and often 10-20% lower base cost compared to custom site-built construction, because factory production is more efficient and less affected by weather delays.
Pre-Fab vs Custom Build
| Factor | Pre-Fab ADU | Custom Site-Built |
|---|---|---|
| Timeline | 8-12 weeks total | 4-6 months |
| Base Cost | 10-20% lower | Standard pricing |
| Customization | Select from floor plans, finishes | Fully custom design |
| Weather Impact | Minimal (factory-built) | Can cause delays |
| Quality Control | Factory-controlled | On-site inspection |
| Size Range | 400-1,000 sq ft | 400-1,200+ sq ft |
| Permits Required | Yes — same as site-built | Yes |
What We Handle for Pre-Fab Projects:
- ✓Unit selection and customization
- ✓Site preparation and foundation
- ✓All permit applications
- ✓Utility trenching and connections
- ✓Delivery coordination and crane placement
- ✓On-site finishing and connections
- ✓All inspections through final CO
- ✓Landscaping and site restoration
The Pre-Fab Process
Step 1: Feasibility Check + Unit Selection
We assess your property to confirm a pre-fab unit can be delivered (access roads, crane reach, lot dimensions). You select your unit size, floor plan, and finishes.
Step 2: Permitting + Site Prep (Concurrent)
While your unit is being manufactured, we submit permits and prepare your site — foundation pour, utility trenching, and connection points.
Step 3: Delivery + Installation
The unit is transported and craned into position on your prepared foundation. Utility connections are made, and on-site finishing work begins.
Step 4: Final Connections + Inspection
All utility connections completed, interior finishes verified, final building inspection, and Certificate of Occupancy issued. You get your keys.
Is Pre-Fab Right for You?
Pre-fab is ideal if you want a faster timeline, are comfortable selecting from available floor plans (rather than fully custom), and your property has adequate access for delivery. Not sure? Our Feasibility Check evaluates both pre-fab and custom options for your specific property.
Same Permits, Same Code, Same Quality
Pre-fab ADUs in Idaho require the same building permits, the same 2018 IRC code compliance, and the same inspections as site-built units. The only difference is where the walls go up — in a factory instead of your backyard. We handle all permitting and inspections regardless of build method.
Interested in a Pre-Fab ADU?
Start with a free Readiness Call. We'll discuss whether pre-fab or custom build is the better fit for your property, timeline, and budget.