A Marina property filed two building permits on August 8 — a $625,000 remodel of the main house and a $120,000 detached backyard ADU — describing a single lot remaking itself front and back for north of $740,000.

At 2550 Filbert Street, in the flats of the Marina, two building permits crossed the wire on the same day. One is easy to miss: permit 202607084732, a $120,000 job to put up a new one-story detached accessory dwelling unit — a backyard cottage, type 5-B, at the rear of the lot. The other, filed the same August 8, is permit 202607084725: $625,000 in additions, alterations, and repairs to the main house out front. Read together, they describe a single property preparing to remake itself front and back, all at once, for something north of $740,000.

That pairing is the story. A detached ADU on its own is the quietest kind of infill — a request the city has spent years making easier to file, one more unit added to a block that will otherwise look unchanged from the sidewalk. But this one arrives bolted to a gut-scale renovation of the existing dwelling, the kind of number ($625,000) that means walls, systems, and a good stretch of the property opened up. The rear cottage isn't the whole project; it's the back half of a much larger reworking of the parcel.

Both permits are still in "filed" status — logged with the Department of Building and Inspection, not yet issued. Nothing has been torn down; no framing has gone up. What exists today is a paper intention, precise about cost and scope, silent on who is behind it. The records name a dollar figure and an address, not an owner or a tenure, and I won't guess at either.

The block itself is quiet on the displacement measures that usually accompany a story like this. Across the Marina, the Rent Board logged eight eviction notices in the last 90 days — none on this stretch of Filbert — against 423 requests to 311 in the past week, the ordinary hum of a residential district. This is not a unit being cleared to make room for something bigger. It's a single-family lot adding capacity: one house becoming a house plus a cottage.

What someone walking past 2550 Filbert tomorrow would notice is nothing at all — a facade unchanged, a rear yard still intact. The change, for now, lives entirely in two permit numbers filed on one August afternoon.