By NW General Contractor. Updated October 11, 2026 after a substantive scope and source review.
Price the site and the dwelling together
A building-only price is not a complete ADU budget. Access, utility connections, drainage, existing structures and required design can change the project. We do not publish a local average without verified underlying project data. Begin with the ADU feasibility checklist and then request a property-specific construction scope.
Conversion versus new construction
- Interior conversion: assess ceiling height, egress, separation, moisture, layout and building systems. Existing space is not necessarily ready for dwelling use.
- Garage conversion: investigate foundation/slab, structure, insulation, utilities and the effect on the rest of the property.
- Detached dwelling: include site preparation, foundation, envelope, utilities, access and restoration as well as interior finishes.
Build a complete cost schedule
- Define dimensions and quantities: room or wall area, cabinet runs, fixtures and the parts of the home being changed.
- Separate retained items from replacements and identify who purchases each product.
- Identify design, engineering, permits, protection, demolition, labor, materials, disposal, finishing and sales tax. Mark exclusions explicitly.
- List allowances with their quantities and installed-versus-supply-only basis. Record how selection changes affect the total.
- Keep an owner contingency separate from the contract price. Agree in writing how concealed conditions and owner changes are authorized.
- Survey or site documentation and any required specialist evaluation.
- Water, sewer or septic review and the actual service connection scope.
- Drainage, excavation, utility trenches and restoration.
- Plans, engineering, permits and applicable fees.
- Appliances, fixtures, finish selections and commissioning/closeout.
Compare proposals without double-counting
Ask each bidder to mark every budget line as included, excluded, allowance or not yet known. Separate supplied-only items from installed work. A pre-approved plan can reduce some repeat design effort but does not remove site-specific approvals or construction costs. Ask what modifications would change its eligibility.
Treat rental returns as a separate decision
Use current comparable rentals and your own vacancy, operating, financing and management assumptions. An advertised rent is not guaranteed achieved income, and a building budget is not an appraisal. Confirm any use restrictions before relying on short-term rental income.
Agree on dependencies before the start
Start with the parcel jurisdiction. An Everett mailing address does not establish that the property is inside city limits. Use Everett Permit Services for city property and county residential permit guidance for unincorporated Snohomish County. Ask which building, plumbing, mechanical, electrical or site-work approvals apply to the actual scope. A building-permit exemption does not waive other applicable requirements.
Review decisions, approvals, long-lead products and safe site access before setting a construction sequence. Ask what changes would require a revised estimate and how approval is recorded. Bring the address, desired use, existing plans and budget boundary to the initial discussion.
Sources and next checks
Source pages reviewed October 11, 2026. Confirm the current requirements for your address and proposed work before committing to a design or start date.
Discuss your project
Request a free estimate with the property address, priorities and available records.