Portland has been building ADUs longer than almost anywhere in the country, which means the code is well-trodden and the housing stock is not. Basements with 6-foot-8 ceilings, galvanized supply lines, 100-amp services and historic overlays are the real variables. Serden Group runs feasibility on all of it, submits a package built to survive plan review, and delivers the unit to a certificate of occupancy under Oregon CCB #239429.
The Portland ADU conversation is rarely about whether it is allowed — it usually is. It is about four things the house will tell you only if someone looks. Whether the basement has the ceiling height and the egress well a bedroom requires. Whether the electrical service can carry a second dwelling. What the system development charges total under the rules in force the month you permit, since Portland's ADU waiver programs have come and gone. And whether a historic or design overlay is going to shape the roof form of a detached unit. We answer all four in feasibility, in writing.
Detached units, attached units, above-garage builds, and basement and garage conversions across Portland's east side and close-in west side. Feasibility, engineered plans, Portland Permitting & Development submittal, site work, utilities and finishes under one contract.
A standalone unit in the back or side yard on its own foundation — kitchen, full bath, bedroom, and its own entry and address.
Built off the existing house on a new footing line, with a separate exterior door and a code-compliant separation wall.
Converting space you already own — insulation, egress, ceiling height, a new kitchen and bath, and a legal second address.
A second story over an attached or detached garage, with the foundation and shear capacity verified before design starts.
Portland zoning decides most of this before design does. We check your base zone and any overlay — historic, conservation or design — against setbacks, building coverage, height and floor-area limits, and we assess whether your existing foundation and framing can carry a second floor. You get a clear go, a build-out-instead recommendation, or a no, with a realistic budget range.
Floor plans, elevations and stamped structural drawings, then submittal and plan-review management through Portland Permitting & Development. Projects in historic or design-overlay districts get the additional review built into the schedule up front, so the timeline you are given is the timeline you actually experience.
Foundation and shear upgrades where the engineer calls for them, framing, roof tie-in, mechanicals, then finishes — sequenced to keep the house weather-tight on an infill lot with almost no staging room. One project manager, daily progress, and a punch-list walkthrough before final inspection.
Portland homeowners choose Serden Group because they're done managing three contractors — we handle everything, pull every permit, and build homes built to last in the Pacific Northwest.
Great experience working with this company. They were professional, responsive, and the quality of their work was solid. They even took the time to treat me to lunch and go over the project details, which I appreciated. Would recommend.
The SERDEN Group did a complete remodel of our two upstairs bathrooms. Every step of the way Dennis, and his team, were communicative, kind, timely, and productive. They worked diligently, caring about the impact of having workers in your home. Everyone was friendly and attended to our creative ideas for the bathrooms. In the end we have two amazing new bathrooms. Our family is grateful for SERDEN and are wonderfully reminded daily of their excellent work. Thank you!
I recently hired Serden Group for a full kitchen and bathroom remodel, and I couldn't be happier with the results! From start to finish, the team was professional, reliable, and detail-oriented. The quality of their work is outstanding — everything from the tile installation to the cabinetry and finishes looks beautiful and well-crafted. They completed the project on time and within budget, which is rare to find these days. I highly recommend Serden Group to anyone looking for top-quality remodeling work. They truly exceeded my expectations!
I had a very pleasant experience with SERDEN GROUP company. They remodeled my bathroom, and I am completely satisfied with the result. Fast and high-quality work. Denis answered all of my questions, suggested great solutions for the renovation, and delivered everything he promised. I 100% recommend them.
Had the pleasure to work with this team on a project for one of their clients. They followed through with every request from start to finish and we can proudly say that, they really put their best foot forward with all their work. Our team would love to continue to work together for future jobs!
Portland allows ADUs broadly, and then the specifics of your lot and your century-old house decide the project. Here is what we plan for.
Building, plumbing, mechanical and electrical permits all run through Portland Permitting & Development, and plan review is the dominant schedule variable — 12–20 weeks is normal, longer where design or historic review applies. We submit a complete package rather than a fast one, because a second correction cycle costs more calendar time than getting the first one right.
Portland assesses one-time SDCs for water, sewer, transportation and parks when a dwelling unit is added, separately from the building permit. Portland has offered ADU waiver and exemption programs at various points, each with conditions and an expiration, so whether one applies depends on the rules in force when you permit. We quote the current schedule as its own line and never assume a waiver.
Alberta, Irvington, Ladd's Addition, Laurelhurst and other districts carry review that applies to new exterior construction — which a detached ADU is. It shapes roof form, siding, window proportion and placement, and adds weeks at the front of the schedule. Entirely workable, as long as it is in the plan from day one.
Basement conversions in Portland's bungalows and four-squares regularly surface 6-foot-8 ceilings that need a lowered slab, egress windows that need a new well cut, galvanized supply lines at the end of their life, knob-and-tube wiring and a service too small for a second dwelling. We inspect for all of it in feasibility and carry a written allowance.
Portland ADU standards, permit requirements and system development charges change, and waiver programs expire. Verify current requirements with Portland Permitting & Development for your address — we handle feasibility, submittal and inspections either way.
From Alameda, Irvington and Laurelhurst to Sellwood, Mt. Tabor, Beaumont-Wilshire and St. Johns — Serden Group builds additions across Portland’s older neighborhoods and the surrounding metro. We know which streets sit inside historic and conservation districts, and what that adds to review.
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Three tiers cover most of what we build in Portland. Every figure includes design, structural engineering, permits, construction and finishes; system development charges are quoted as a separate line. Oregon charges no sales tax.
Ranges are planning figures, not quotes. Your fixed price comes after feasibility, a site visit and a written scope.
East side, close-in west side, and the inner suburbs.
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The services that pair most often with an ADU, plus the planning guides our Portland clients read first.
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