Define the project scope
Separate verified conditions from assumptions and owner preferences before comparing prices.
- What is included?
- What still needs field verification?
- What could trigger extra cost?
New 132-page guide • reviewed Sep 22, 2026
Preview 3 sample pages before buying
Home Addition Cost Per Square Foot Guide
$16.99USD • one-time purchase
Plan addition square footage, structure, systems, permits, allowances and contractor scope.
- 132 pages of planning guidance and reusable worksheets
- 24 project modules with scope, quote-check and decision pages
- Links to relevant HomeCostEngine calculators and guides
- Independent government or industry sources for verification
- Support email and optional HomeCostEngine email updates
What is inside
A full project-planning workflow, not a short checklist.
The book is structured as 24 planning modules. Each module includes a current-planning page, a scope worksheet, a contractor quote check and a decision/action page. The final 20 pages are reusable records for measurements, allowances, risk, schedule, payments, warranties and closeout.
Major modules
- 1. Project purpose and space needs
- 2. Property constraints
- 3. Existing house documentation
- 4. Concept layout
- 5. Square footage and dimensions
- 6. Foundation questions
- 7. Structural framing
- 8. Roof tie-in
- 9. Exterior wall system
- 10. Windows and doors
- 11. Insulation and air sealing
- 12. HVAC extension or new system
- 13. Plumbing additions
- 14. Electrical additions
- 15. Lighting and controls
- 16. Interior walls and ceilings
- 17. Flooring and finishes
- 18. Kitchen or bath fixtures
- 19. Permits and inspections
- 20. Design and engineering scope
- 21. Site access and protection
- 22. Allowances and contingency
- 23. Quote comparison and schedule
- 24. Final inspection and closeout
Use the book with these HomeCostEngine tools
The PDF links back to the site so you can move from a planning worksheet into the relevant calculator or guide when you need a quantity, scenario or quote-comparison check.
- Square Footage Calculator
- Project Contingency Calculator
- Contractor Quote Comparison
- Roof Replacement Calculator
Independent sources used for the 2026-2027 edition
This edition was reviewed on September 22, 2026. We link to the source rather than pretending that a future 2027 rule, incentive or local permit requirement is already known. Recheck source pages when you are ready to buy or contract the work.
Questions & updates
Need help using the guide?
Email [email protected] and include the book title plus enough project detail for us to understand your question.
Want new calculators, revised guides and future book releases? Join the HomeCostEngine email list →
Important limitation
The guide helps organize scope, questions and budget decisions. It does not replace a property inspection, contractor bid, engineering design, legal advice, manufacturer instructions, permit review or local code requirements.
Free preview
Preview 3 sample pages.
See the planning style before you buy. The full PDF remains protected behind checkout.
Build the planning worksheet
Record measurements, selected products, allowances, access constraints and restoration work in one place.
Compare contractor quotes
Normalize proposals before comparing the bottom line so scope differences do not hide inside the price.
✓ Same scope✓ Allowances clear✓ Warranty stated✓ Change-order rules
Reader reviews
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★★★★★ 4.7/5
HomeCostEngine editorial planning score: 4.7/5. Verified purchaser reviews will be shown separately once received.
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Home Addition Cost Per Square Foot Guide
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