Room Addition & Whole-Home Remodel

Room additions + whole-home remodels in the Twin Cities — design-build from sketch to certificate of occupancy

Primary suite additions, second-story additions, and whole-home renovations with architectural drawings, structural engineering, permitting, and a 2-year structural warranty.

Room additions + whole-home remodels in the Twin Cities — design-build from sketch to certificate of occupancy

Room additions and whole-home renovations are the highest-ticket, longest-cycle projects in residential remodeling — and the most strategically important for a design-build firm.

A single primary suite addition in the Twin Cities (400-600 sq ft over the garage or on a slab extension) runs $120,000-$200,000. A full second-story addition runs $200,000-$400,000 depending on structural complexity. Whole-home renovations of 1,500-2,500 sq ft (full kitchen, multiple baths, new flooring, windows, mechanical systems) run $200,000-$500,000 for premium finishes.

The project cycle from first inquiry to permit issuance alone is typically 3-6 months for additions — Anna captures the critical qualifier at intake: is the homeowner planning now for a future start, or is there a hard deadline (baby due date, aging parent moving in, new home purchase with planned renovation)?

What's included

  • Architectural drawings + structural engineering
  • Foundation + framing + roofline tie-in
  • Weatherproofing + window + door package
  • All mechanical (electric, plumbing, HVAC extension)
  • Complete interior finish matching existing home
  • 2-year structural + craftsmanship warranty

Related services

Room Addition & Whole-Home Remodel — common questions

How long does a room addition take?
Total project time from first inquiry to move-in: 5-12 months depending on scope. Design + permitting: 3-6 months (architectural drawings, structural engineering, city plan review). Construction: 12-24 weeks for a primary suite addition, 6-9 months for a second-story or whole-home renovation.
Do you handle the architectural drawings?
Yes — Cornerstone is a true design-build firm. Our designer produces concept drawings; we coordinate with a structural engineer for load-bearing assessments and stamped drawings required for permit. If you have already worked with an outside architect, we can build to their plans as a traditional GC.
Will I need to move out during a whole-home renovation?
Depends on scope. Most whole-home renovations: yes, for at least the kitchen and primary bath phases (4-8 weeks). We coordinate timing with you and can phase the work so the kitchen and at least one bathroom are operational at all times. Some clients rent a short-term home or stay with family during peak disruption phases.
What permits are required and who pulls them?
Additions and whole-home renovations require a building permit, electrical permit, plumbing permit, and mechanical permit from the local building authority (Minneapolis, St. Paul, or suburban municipality). Cornerstone pulls all permits as the licensed GC of record. Inspections coordinated in sequence (framing, rough-in, insulation, drywall, final).

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