How much do Mechanical Plans cost?

Standalone ADU mechanical plans start at $995 for an ADU up to 600 SF and scale to $2,095 for 1,001–1,200 SF. Mechanical can also be combined with another discipline starting at $1,195, or included in the Full MEP Package starting at $1,495.

Mechanical plan pricing by size

What the mechanical fee covers

• Manual J heat load calculation sizing heating and cooling capacity to your ADU's square footage, windows, insulation, and California climate zone.
• HVAC system design and layout — typically a ductless mini-split heat pump, with equipment location and any ducting shown.
• Equipment schedule listing make, model, capacity (BTU/hr), and efficiency ratings that meet current Title 24 minimums.
• Ventilation design per ASHRAE 62.2 and Title 24, including bathroom exhaust fans, kitchen exhaust, and condensate drainage.

Why mechanical scales with square footage

A larger conditioned area carries a higher heating and cooling load, may require upsized or multi-zone equipment, and demands higher ASHRAE 62.2 ventilation rates. More area means more calculation and drafting work, which is why each size bracket steps up.

Common pairings and add-ons

Mechanical is frequently ordered with the Title 24 energy report (+$240), because HVAC efficiency values on the plans must match the energy model exactly. Ordering both from one team eliminates the most common mechanical correction. Turnaround upgrades are available: Priority (3 business days) +$299 or Expedited (1–2 business days) +$599; standard 5-business-day turnaround is included.

What is not included

Our fee covers the plans only. The physical equipment, installation labor, city permit fees, and HERS field verification of refrigerant charge or fan watt draw (where applicable) are billed separately by suppliers, contractors, the city, and a HERS rater.

How to know which tier you are in

Use the conditioned floor area of the ADU — the heated and cooled living space — to pick your bracket. A backyard studio at 540 SF is the $995 tier; a one-bedroom at 720 SF is the $1,295 tier. If your unit sits right at a bracket boundary, the published table removes any guesswork, and we confirm the size at order intake so the price you see is the price you pay. There is no sales tax on the plan service and pricing is identical anywhere in California.

Every mechanical order includes two revisions, city corrections, and permit-ready PDF delivery. See the pricing page or start your order.