Michigan addition planning

Home-Addition Cost Calculator

Model the addition area—not total house area—then make the project type, site complexity, finish level, and reserve visible.

Complete-budget map

The square-foot result is only the center of the budget.

Do not treat these categories as fixed percentages. Use them as a completeness check when comparing design proposals and contractor bids.

Design and approvals

Survey, architecture, engineering, energy work, zoning, permits, and plan review.

Site and foundation

Access, protection, excavation, drainage, footings, walls, slab or crawlspace, and restoration.

Structure and envelope

Framing, tie-ins, roofing, flashing, siding, windows, doors, insulation, and air sealing.

Utilities and interiors

Electrical, plumbing, HVAC, drywall, trim, flooring, fixtures, cabinetry, painting, and commissioning.

Owner and risk costs

Temporary living, financing, selections, storage, delays, concealed conditions, changes, and reserve.

Continue the addition silo

Move from a range to a bid-ready plan.

Home-addition cost guideTypes, examples, scope, and contractor questions →Contingency calculatorSeparate known costs from uncertain costs →Bid-comparison guideNormalize allowances, exclusions, payments, and warranty →Permit checklistPrepare the local approval questions →

Estimate limits: This is educational arithmetic, not an observed bid, appraisal, design, code determination, or promise. Local factors and type multipliers are broad planning assumptions. Site work, utilities, design, approvals, products, contractor availability, and written proposals determine actual cost.