October 30, 2025
Altadena Project Update: Two Weeks From Completion
“Is a Prefab ADU Cheaper?”
(Short answer: sometimes. But here’s what really determines the cost.)
When homeowners start exploring accessory dwelling units (ADUs), one of the first questions that comes up is simple: “Is prefab cheaper?”
It’s a fair question — but a loaded one. The truth is, sometimes yes, sometimes no. It all depends on what kind of prefab you’re talking about and what you’re comparing it to.
Not All Prefab Is Created Equal
“Prefab” just means prefabricated — parts of the structure are built in a factory, shipped to the site, and assembled there.
That could mean:
- A high-end steel-frame ADU with triple-pane windows and luxury interiors, or
- A low-cost mobile unit with thinner walls and minimal insulation.
Both are “prefab.” But they live in completely different worlds in terms of quality, comfort, and long-term value.
Some of the best homes in the world are prefab. You can order a laser-cut, panelized home from Germany, ship it to Maryland, and build it on the water for a couple million dollars.
So prefab doesn’t always mean cheap — it means controlled.
Where the Savings Come From
Here’s where prefab can actually save money compared to traditional construction:
- Factory Labor Is Cheaper
- Labor in a factory is streamlined — no weather delays, no endless subcontractors, no jobsite downtime. That efficiency cuts costs.
- Faster Build Times
- In Los Angeles, where permitting and labor costs are sky-high, speed equals savings. Prefab ADUs can be installed in weeks, not months, which means less rent lost and fewer surprises.
- Reduced Waste
- Factories optimize material use to the inch. That means less over-ordering, fewer mistakes, and more predictable costs.
- Predictable Pricing
- Because prefab projects are engineered and approved in advance, you avoid the endless change orders and hidden costs that plague traditional builds.
Where Prefab Can Cost More
There are also reasons prefab can seem more expensive upfront:
- Higher-quality materials — At LiveLarge, we use steel frames, triple-pane windows, double-insulated ceilings, and low-VOC interiors for durability, quietness, and health. Those materials cost more than the bare minimums you’ll find in many stick-built ADUs.
- Craning and delivery costs — Large prefab units need cranes and transport trucks, especially in dense neighborhoods like Los Angeles.
- Site work still matters — Foundation, trenching, and hookups are site-dependent and can vary widely depending on your lot.
So while the sticker price might be higher than some “cheap prefab” kits, the value per square foot — for the quality, comfort, and lifespan — is usually much higher.
So, Is Prefab Cheaper?
If you’re comparing the same quality — say, a 750-square-foot ADU with luxury finishes and energy-efficient materials — prefab construction is typically 15–25% more affordable than traditional construction in California.
You’re not just paying less — you’re avoiding the headaches, delays, and unpredictable costs of on-site builds.
If you want to see exactly how much prefab ADUs cost in your area, check out our Full ADU Cost Breakdown — or see what’s possible with our Los Angeles prefab projects.
The Bottom Line
Prefab doesn’t automatically mean cheaper. It means smarter — faster timelines, higher precision, and better predictability.
With LiveLarge, you’re not cutting corners; you’re just cutting waste.
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