Walk the house with an experienced second-story builder

Why this matters early

A Seattle pop-up is one of the most house-specific projects in residential construction. The same square footage on a 1908 Craftsman with a brick-and-mortar foundation costs wildly differently than on a 1962 ranch with a poured-concrete crawlspace. An experienced builder will tell you in 60 minutes which world you're in — and that determines whether you're in the $300K bucket or the $700K bucket before you've spent a dollar on design.

What the builder is checking

• Foundation type and condition. Brick-and-mortar (pre-1920), unreinforced concrete (1920–1950), or modern poured concrete (1950+). Each carries the new load differently. Many older foundations need a partial or full retrofit before they can carry a second story.
• Roof structure. A simple gable roof comes off cleanly. A complicated hip-with-dormers gets expensive to remove.
• First-floor framing. Balloon framing (continuous studs from sill to roof) vs. platform framing changes the structural strategy.
• Mechanical systems. Knob-and-tube wiring, galvanized water lines, asbestos pipe wrap, original cast-iron drains. Each surfaces differently in the cost stack.
• Lift vs. retrofit. Sometimes the cheapest path to a second story is to lift the whole house, build a new foundation and ground floor, and drop it back. Counterintuitive but real for some Craftsman bungalows. A builder who has done it will tell you within minutes whether your house is a candidate.

How to find one

Use the SDCI permit history tool and filter for "addition" permits in your neighborhood over the last three years. The contractor names that come up repeatedly are your local specialists. Three to five names is plenty. Most do free initial walk-throughs because that's how they qualify the project.

What you should walk away with

• A 1-page set of notes you can hand to a designer.
• A rough cost band ("$400K–$550K range" or "more like $700K with the foundation work").
• An honest read on whether the project pencils out before you spend on design.