Basement Remodeling in Tacoma: Plan and Hire

Define the finished space before hiring

Write a room-by-room description: family room, bedroom, bathroom, laundry or independent dwelling. Tell each bidder which fixtures you want to retain and which walls you want to move. Have the designer measure ceiling heights, beams, stairs and proposed window openings before you approve a layout.

Tacoma requires section drawings for basement remodels and floor plans for interior modifications. Structural alterations and enlarged exterior openings can require framing plans. Have your bidder identify who will prepare these drawings, respond to review comments and price resulting design changes. [1]

The City's alteration tip sheet discusses ceiling-height allowances for existing basements under Appendix J, but it references older code editions, including 2018 codes. Ask Planning and Development Services to confirm the applicable code, ceiling-height allowances and energy requirements for your property. Do not treat the tip sheet's numerical allowances as confirmed current requirements or assume an existing finished room meets them. [1]

Check drainage before covering the basement

Show bidders water stains, damp areas and any history of backups. Request a separate investigation and repair scope before approving insulation, wall coverings or flooring. Have the contractor explain the suspected water source and how you will check the repair before finishing the space.

Tacoma says property owners maintain the side sewer between their building and the public main. The City recommends locating and assessing that pipe before additions or significant improvements over it. For a proposed bathroom, have the plumber assess the existing drainage connection and identify any required sewer work. [3]

If a service provider clears a blockage, request its location and probable cause in writing. Tacoma notes that a camera inspection can help assess pipe condition after the provider clears the blockage. Keep that report with your remodeling plans so bidders can address the same known condition. [3]

Separate a household remodel from an ADU

Discuss an independent basement dwelling with the City before committing to a construction contract. Tacoma defines an accessory dwelling unit, or ADU, as a second, smaller dwelling on the same lot and requires cooking, living, sanitation and sleeping facilities. Its published standards limit ADU living area to 1,000 square feet, excluding garages and other non-living areas. [2]

Have the designer address fire separation, bedroom emergency escape, alarms, insulation and energy requirements. Tacoma requires each dwelling to have maintenance access and control of its heating and water heater. The City also requires interconnected smoke and carbon monoxide alarms for attached ADUs. Include these items in the feasibility review before selecting cabinets or appliances. [2]

Discuss electrical service, metering and permit-fee classification with the electrician and Tacoma Power. The electrical code requires independent metering for newly constructed or remodeled dwelling units. Its owner-permit conditions require applicants to affirm that they do not intend to rent, sell or lease any part of the building for at least 24 months after final electrical inspection. Tell the electrician about intended rental use before deciding who will perform the work. [4]

Assign permits and inspection stages

Tacoma's residential alteration permit often combines building, plumbing and mechanical review. The City asks applicants to include replaced, relocated and new plumbing and mechanical fixtures in the scope, including exhaust fans for bathrooms, laundry areas and kitchens that vent outdoors. Have the bidder list fixtures and ventilation work rather than use a broad allowance for a finished bathroom. [1]

Electrical work has separate permit requirements under Tacoma Power's code. For hired work requiring an electrical permit, the code generally requires a Washington-licensed electrical contractor, subject to stated exemptions. Identify who will hold the permit, arrange access and request inspections. Require approval before workers conceal wiring, and collect final inspection records at completion. [4]

Have the contractor schedule demolition, repairs, rough work, inspections and finishes as separate milestones. Agree on a written process for discoveries such as damaged framing or drainage changes. Tacoma requires a field revision for changes to scope and value after permit issuance, with potential revised permit and review fees. [5]

Compare complete bids and permit allowances

Give each bidder the same drawings and fixture list. Request separate amounts for preparation, drainage repairs, structural work, insulation, electrical, plumbing, ventilation and finishes. Have bidders identify exclusions, product allowances, disposal, permit fees and responsibility for design revisions. Compare the proposed work before comparing totals.

Tacoma bases residential alteration permit fees on work valuation, including permanent finishes and systems. Staff use the alteration valuation table to assess scope. Its percentages and example square-foot values are administrative references, so obtain a construction price from an itemized contractor proposal. [5]

The chart shows two selected single-family electrical permit categories. Tacoma Power directs multifamily dwelling installations and single-family dwellings exceeding 400 amps or 4,000 square feet to Table B. For a basement ADU conversion, confirm the classification with Tacoma Power before budgeting these fees. Have the electrician identify other applicable permit charges. [4]

Request a payment schedule tied to documented progress and an agreed completion package. Include inspection records, product information, warranties and instructions for accessing equipment. Have the contractor distinguish the proposed construction schedule from time needed for design and permit review.

Selected Tacoma Power single-family electrical permit fees

Match the project to the next step

Your hiring checklist

1. Write the intended use of each room and state whether you plan an independent dwelling.
2. Photograph damp areas and gather previous repair and permit records.
3. Request measured drawings showing beams, stairs, windows and equipment access.
4. Give bidders the same fixture list, finish selections and repair scope.
5. Name the person responsible for each permit and inspection in the contract.
6. Have the electrician confirm the applicable fee classification for the proposed occupancy and service.
7. Agree on written pricing and approval for changes before work proceeds.
8. Collect final inspection records and warranty documents at completion.

Frequently Asked Questions

Do I need a permit to finish an existing basement?

Tacoma lists finishing an existing basement among residential alteration projects. Ask Planning and Development Services to confirm the permit and drawings for your scope, including structural, plumbing and mechanical work. Confirm electrical permits with Tacoma Power. [1] [4]

Can I turn the basement into a rental apartment?

Request an ADU feasibility review first. Tacoma requires permits for ADU creation or conversion and specifies dwelling facilities, fire separation, emergency escape, alarms and utility requirements. Confirm how those standards apply to your layout, and tell the electrician about rental plans before discussing owner-permit eligibility. [2] [4]

Can the contractor cover wiring before inspection?

Tacoma Power prohibits covering or concealing wiring before its Electrical Inspection Office approves it. If workers conceal it before approval, the code requires exposing it for inspection. Include this inspection stage in the schedule. [4]

Does the City's valuation table tell me the remodeling cost?

The City uses the table to verify alteration valuation for permit administration. It does not establish the price a contractor will charge for your basement. Request an itemized proposal based on your measured space, intended use and repair needs. [5]