How to Check Construction Permits When Buying or Selling a House in Seattle

When buying or selling a house in Seattle, checking whether past construction work was properly permitted matters more than most people realize. Here’s how I walk clients through checking permits, handling unpermitted work if you find it, and what the process and costs actually look like in Seattle and King County.

Checking Construction Permits

1. Understand What Requires a Permit

Most structural work needs a permit: additions, converted garages, new decks over 200 square feet, electrical and plumbing changes, and load-bearing wall removal. Cosmetic work like paint or flooring generally doesn’t. If you’re not sure whether a specific project needed one, that’s exactly what SDCI’s permit counter is for.

2. Request Permit Records from the Seller

If you’re buying, ask the seller directly for permit documentation on any visible renovations, additions, or converted spaces. A seller who has this paperwork ready is usually a good sign; one who can’t produce it is worth a closer look.

3. Check With Seattle DCI or King County Permitting

For property inside Seattle city limits, the Seattle Department of Construction and Inspections (SDCI) maintains permit records searchable by address through the city’s online permitting portal. For unincorporated King County, the county’s Permitting Division handles this instead. Either way, you don’t need to guess, the record either exists or it doesn’t.

4. Use Online Resources

Seattle’s online portal lets you pull permit history without an in-person visit, which saves a step compared to some other jurisdictions. It’s worth doing this before an offer, not after, so surprises show up while you still have negotiating room.

5. Hire a Professional Inspector

A qualified home inspector can often spot signs of unpermitted work, mismatched framing, odd electrical panels, additions that don’t match the original footprint, even when the paperwork trail is unclear.

Handling Unpermitted Work

1. Identify the Extent of the Work

Not all unpermitted work is equally serious. A finished basement without a permit is a different conversation than an addition with no visible support beams. Get a contractor’s honest read on what you’re actually dealing with before deciding next steps.

2. Consult With SDCI or the County

Bringing the issue to the city or county proactively, rather than waiting for it to surface during a sale, generally gets a more cooperative response than being reported by a neighbor or discovered during an inspection.

3. Apply for a Retroactive Permit

Seattle and King County both allow retroactive permitting in many cases, sometimes requiring the work to be exposed for inspection first if it’s not visible or documented.

4. Make Necessary Corrections

If the work doesn’t meet current code, expect to make changes before a retroactive permit gets approved. This is often the most expensive part of the whole process, more than the permit fee itself.

5. Pay Any Associated Fees

Retroactive permits often carry a penalty on top of the standard fee, sometimes double, since the city is essentially processing an after-the-fact application instead of one submitted before work began.

The Permitting Process

For anyone planning new work rather than fixing past work: determine whether you need a permit, submit an application through SDCI or King County, go through plan review, receive the permit, schedule the required inspections as work progresses, and get final approval once everything checks out. Seattle’s review timelines vary a lot by project complexity and current permit volume, so build in buffer time.

Associated Costs

Permit fees are generally based on the value of the project, so a small repair costs far less than a major addition. Add in potential retroactive penalties, required corrections, and inspector fees if you’re dealing with unpermitted work discovered after the fact, and the total can climb well past the original permit fee alone.

Solutions for Unpermitted Work

If all of this sounds like more than you want to take on before selling, you’re not alone, and you don’t have to resolve it first. I buy houses in Seattle and King County with unpermitted work exactly as they are. You don’t need to pull retroactive permits, make corrections, or deal with SDCI before we talk. I factor the condition into a fair cash offer and handle the rest myself.

A Case Where Checking Permits Saved a Buyer From a Bad Surprise

A buyer I worked with in Ballard was under contract on a house listed with a finished basement rec room as a major selling point. Pulling the SDCI permit history before closing showed no record of any permit for finishing that space, not for the electrical, not for the egress window that would have been required for it to legally count as habitable square footage. The listing agent hadn’t verified this, and the sellers genuinely didn’t know it mattered since a previous owner had done the work decades earlier. The buyer used the finding to negotiate a $15,000 price reduction to cover bringing the space up to code after closing, rather than walking away entirely, since the rest of the house checked out fine.

This is a good example of why checking permit history isn’t just a box to check, it’s leverage. Sellers rarely disclose unpermitted work proactively, not always out of dishonesty, but because they genuinely don’t know their own home’s permit history unless they pull it themselves. A ten-minute search on the county’s online permit portal before writing an offer, or before accepting one, can turn into real negotiating room or, in worse cases, a reason to walk away from a deal entirely.

If you’re dealing with unpermitted work and want to sell without fixing it first, call (206) 900-8173 or send us a message.