What is the difference between ADU and residential MEP plans?

The core engineering is similar, but ADU and residential MEP plans differ in scale, scope, and pricing. ADU plans cover accessory dwelling units up to 1,200 SF, while residential plans cover single-family homes, additions, and remodels — projects that are often larger and more system-intensive.

Key Differences

The clearest contrasts are in size limits and starting prices. The table below summarizes how the two compare.

Scope Considerations

Beyond price, the design work itself differs in a few practical ways.

• Connections — ADUs often tie into an existing primary residence's utilities, which shapes plumbing and electrical design and load calculations.
• Equipment — smaller ADUs frequently use compact systems like mini-splits, while larger homes may need full ducted HVAC and larger panels.
• Load complexity — bigger residential projects generally involve more circuits, fixtures, and coordination across disciplines.

Choosing the Right Package

If your project is a standalone or attached accessory unit, ADU pricing typically applies. For a main home, addition, or substantial remodel, residential pricing applies. For ADU cost details, see our cost of ADU MEP plans page, and for the residential structure see our residential MEP plans page.

Classification can depend on how your jurisdiction defines the unit and the work — requirements vary by jurisdiction, so verify with your local building department. If you're unsure which path fits, email orders@mepplansusa.com or compare options on our pricing page, then place your order and we'll confirm the right package for your scope. As a rule of thumb, a self-contained second living unit on the property points toward the ADU path, while expanding or rebuilding the main dwelling points toward the residential path. Either way, both sets are delivered permit-ready, include two revisions and city correction responses, and carry no hidden fees or sales tax, so the workflow on your end stays the same regardless of which category your project falls into.