Two contractors can price the same floor plan thousands of dollars apart without either price being obviously wrong. Some differences reflect craftsmanship or materials; others reflect excluded work, provisional allowances or misunderstandings of the scope.
Start with the same written scope
Before reviewing numbers, make sure each contractor has the same floor plan, specifications, site information and expectations. A vague phrase like “complete room addition” may hide different assumptions about insulation, windows, paint, flooring, cleanup and permit responsibility.
Ideally, both proposals should identify the same measurable deliverables: foundation type, framing materials, roofing specification, window schedule, heating/cooling method, plumbing fixtures, electrical circuits and finish level.
Turn headline prices into full project totals
A common comparison mistake is putting two bottom-line numbers next to each other without adding items that a quote explicitly excludes. Ask each bidder who is paying for design, structural engineering, permits, surveys, site preparation, utility upgrades and inspection rework. Confirm whether taxes and cleanup are included.
| Item | Quote A | Quote B |
|---|---|---|
| Construction base | $120,000 | $137,000 |
| Permits + design | $9,000 | Included |
| Missing work / allowances | $13,000 | $20,000 |
| Adjusted comparison | $142,000 | $157,000 |
These are fictional illustration amounts, not supplier quotes. The adjusted numbers help you identify questions; they do not prove which contractor offers better quality.
Verify credentials and references
Use your state or local licensing lookup where licensing applies. Ask for certificates of insurance and check their validity directly with the insurer when appropriate. Confirm that the company has experience with the type of addition you are building; an interior remodeling portfolio is not the same as a second-story structural project.
Request recent client references and ask about change orders, on-site supervision, communication, missed deadlines and how defects were corrected. Be cautious with claims of urgency, pressure to pay a large amount before materials or work are scheduled, or unwillingness to put expectations in writing.
Review payment milestones and change orders
Good agreements describe when payments become due, what constitutes completion, who handles inspections and how unexpected conditions are documented. A change order should normally record a changed scope, price effect and scheduling effect before work proceeds.
Check how the contractor will handle weather delays, materials substitution, access to your home, protection of belongings and disputes. Laws governing deposits, lien notices, cancellation rights and contracts vary by state.
Use the free bid comparison worksheet
Our contractor quote comparison tool separates base price from design, permits, excluded work and miscellaneous costs. It also reminds you to check licensing, insurance, milestone schedules and written warranties.
- Enter base prices exactly as stated in each written proposal.
- Record which fees are included and add excluded expenses where known.
- Compare allowances using realistic actual material selections.
- Flag items included by one contractor but not the other.
- Save or print the worksheet and send clarifying questions before signing.
Additional cost context
- Angi (2026), How Much Does a Home Addition Cost?
- Angi (2026), How Much Does an ADU Cost to Build?
- Angi (2026), How Much Does It Cost to Add a Second Story?
- HomeGuide, Home Addition Cost
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