What's the difference between residential and ADU MEP plans?

Residential and ADU MEP plans use the same engineering disciplines but differ in project type, size limits, and pricing. Residential plans serve single-family homes, additions, and remodels, while ADU plans serve accessory dwelling units up to 1,200 SF — typically smaller and often connected to an existing home.

Side-by-Side Comparison

The fastest way to see the difference is in the size caps and starting prices for each path.

Design Differences

The engineering itself shifts with the size and connection type of the project.

• Utility ties — ADUs frequently connect to an existing home's services, affecting plumbing and electrical routing and load calculations.
• Equipment scale — ADUs often use compact systems like mini-splits, while larger homes may need full ducted HVAC and bigger electrical panels.
• Coordination — larger residential projects typically involve more fixtures, circuits, and cross-discipline detail.

Which One Applies to You

If you're building or converting an accessory unit, ADU pricing usually applies; for a primary home or major remodel, residential pricing applies. Classification depends partly on how your city defines the unit — requirements vary by jurisdiction, so verify with your local building department before assuming a category.

For ADU specifics, see our cost of ADU MEP plans page, or compare the full structure on pricing. A helpful shortcut: an independent second dwelling on the lot generally follows the ADU path with its lower starting prices and 1,200 SF cap, while a primary residence, addition, or full remodel follows the residential path with its larger 3,500 SF flat-rate range. Both share the same permit-ready delivery, two included revisions, city correction responses, and no hidden fees, so only the size limits and pricing tiers really change between them. When you're ready, start your order and we'll confirm the right package and price for your project.