The direct answer
A home addition estimate should cover design responsibilities, surveys and engineering, permits, site access, excavation, foundations, framing, roofing, exterior enclosure, mechanical systems, utilities, interiors, tie-ins, restoration, schedule, allowances, and exclusions. It should state what is based on completed plans and what remains an assumption.
What to check in the documents
Design and approvals
Clarify responsibility for drawings, engineering, surveys, energy calculations, permit fees, revisions, and responding to plan-review comments.
Site and structural work
Confirm access, demolition, excavation, soil assumptions, foundations, framing, structural connections, temporary protection, and weather exposure.
Exterior tie-ins
Define roofing transitions, flashing, siding or stucco matching, windows, doors, drainage, landscaping disturbance, and exterior restoration.
Building systems
Check heating and cooling capacity, electrical service, plumbing routes, utility upgrades, controls, testing, and inspection responsibility.
Existing-home impacts
Identify openings, dust protection, occupied-area access, flooring transitions, finish matching, temporary utilities, and restoration limits.
Warning signs to clarify
- Price based on incomplete drawings without listed assumptions
- No soil, utility, or existing-structure qualifications
- Existing-home restoration described as “match existing” with no limits
- Permit and design responsibilities left unassigned
- Major upfront payments before measurable work
Questions to ask the contractor
- Which plans and revisions form the pricing basis?
- What site, soil, utility, and existing-condition assumptions were used?
- How are roof and exterior finishes tied into the existing home?
- Are utility or service upgrades included?
- Which disturbed areas will be restored and to what standard?
Practical context
Example: the new room may be clear while the tie-in is not
A proposal can describe the new walls, windows, and finishes but say little about opening the existing house, rerouting utilities, matching flooring, repairing roofing, or restoring landscaping. Those connection points often carry more uncertainty than the new room itself and should be discussed before signing.
This guide provides general construction-document information, not legal advice, engineering, inspection, appraisal, or a guarantee of final project cost. Project documents and applicable requirements vary.