Attic & Basement Remodeling Contractor in Dunthorpe, OR
Typical range: $30,000 – $100,000 Final price depends on scope — your free estimate is itemized in writing.
Estimate your project →Attic Conversions in Dunthorpe
Dunthorpe attics are worth converting because the houses are big and the rooflines are steep. A 1920s Tudor or a Colonial on Palatine Hill often has more usable area up there than a newer house has in a whole second storey.
Three numbers decide whether it works, and they come from the Oregon Residential Specialty Code:
Ceiling height. In an existing house the minimum is 6'8". Under a sloped ceiling, no more than half the required floor area may sit below 6'8", and anything under 5'0" does not count toward the room at all. That last rule is the one that kills conversions people thought were fine.
Room size. A habitable room needs at least 70 square feet that meets those height rules.
Stair headroom. At least 6'2" measured from the stair nosing. Rebuilt stairs in the same opening need 6'4". On older Dunthorpe houses the original attic stair is frequently the thing that has to change.
If the headroom isn't there, a dormer buys it. A shed dormer gives the most space per dollar and nearly full headroom wall to wall; a gable dormer suits a Colonial or Craftsman roofline better and keeps the house looking like itself from the street. On a street where the houses are the point, that matters.
We read the roof first and tell you which one the house will take. See our full attic remodeling page, or the guide on whether an attic conversion is worth it in Portland.
Basement Finishing in Dunthorpe
A Dunthorpe basement is usually the cheapest room the house will ever gain, because the foundation, walls and roof already exist. What decides the budget is three things, and we check all three before quoting.
Water. The lots here slope toward the Willamette, and a hillside basement that takes water in a Portland winter will destroy new framing and drywall inside one season. Drainage and vapor control go in first or the rest is wasted.
Egress. A basement bedroom needs an emergency escape opening, and the code is specific: 5.7 square feet of net clear opening, at least 20" wide and 24" high, with the sill no more than 44" above the floor. An opening at a grade-level sill can drop to 5.0 square feet. A window that merely hits 20 by 24 does not qualify — the area rule is separate. In a poured foundation this means cutting the wall and building a well, and it is the line item people never budget for.
Headroom and services. Ducts, beams and plumbing runs set the finished ceiling. A beam may drop to 6'0" if it stays within two feet of a wall, or 6'2" if it covers no more than 10% of the floor. Sometimes a run can be rerouted. Sometimes it can't, and you should know that before demolition rather than after.
More on scope and pricing on our basement remodeling page and in the 2026 Portland basement remodel cost guide.
Dunthorpe Permits Are County, Not City
Dunthorpe is an unincorporated area of Multnomah County. It is not inside Portland and it is not inside Lake Oswego, even though it sits between them. Permits run through the county rather than the City of Portland's residential process, and we confirm the current path for your specific address before filing anything.
The part that catches people is septic. Where a Dunthorpe property is on a private system rather than public sewer, adding a bedroom triggers a review of whether that system can carry the extra load — an Authorization Notice. An interior remodel that adds basement-level plumbing or a basement bedroom triggers a Septic Review Certification on top of the building permit.
That review is a minimum of 20 working days on its own, and as of August 2026 the program is running with extended delays. It is sequential, not parallel: it has to clear before the work it affects can proceed.
This is the single most common reason a Dunthorpe attic or basement bedroom lands months behind schedule, and it is not something you discover halfway through. We check whether the property is on septic at the first visit and build the review into the timeline from the start.
What Older Dunthorpe Houses Need First
Most of Dunthorpe went up between the 1920s and the 1960s — Colonial Revival, Tudor, Georgian and mid-century, on large lots with mature trees. Beautiful houses, and each era brings its own list.
Floor framing. Attic joists in a house of this age were often sized to hold up a ceiling, not to carry people and furniture. Converting means either sistering them or adding a beam, and on a long span that sometimes loads a basement post that was already working hard. An engineer's look costs a few hundred to a few thousand dollars and is cheaper than guessing.
Wiring. Knob-and-tube still turns up in Dunthorpe attics, usually buried under insulation. It comes out before anything is finished over it. Electrical goes through a licensed electrician.
Lead paint. Anything built before 1978 is presumed to have it, which covers almost every house here. Disturbing it legally requires a lead-based paint renovation certification. Zurc holds one. Ask any contractor bidding your attic for theirs — it is a licence, not a claim, and you can look it up.
Asbestos. Old duct wrap, vermiculite insulation and some floor tile may contain it. We do not hold an abatement licence and we do not touch it. If testing finds asbestos, it goes to a licensed abatement contractor first and we work after they clear it.
Whole-house work beyond these two rooms is on our home remodeling page.
What It Costs in Dunthorpe
These are the same figures as our published Portland cost guides, because it is the same work. Dunthorpe sits toward the top of each range — the houses are larger and older and the lots are steep.
Attic conversion: $30,000 to $70,000. Roughly $30 to $50 per square foot for a basic finish, $50 to $75 with a bathroom, $75 to $100 and up for a full suite.
Adding a dormer: $15,000 to $30,000 on top, depending on size and roofline.
Basement finish: $25,000 to $75,000 for 600 to 1,200 square feet. Tiered the same way — $25 to $40 per square foot basic, $40 to $65 mid-range with a bath, $65 to $100 and up for a full suite.
The line items that move most on these houses: egress window with well and excavation $3,000 to $6,000; floor joist reinforcement $1,000 to $10,000; structural engineering $400 to $3,000; adding a bathroom $8,000 to $18,000; permits $500 to $2,000. Where a basement needs drainage and a sump pump before framing can start, add $10,000 to $25,000.
You get all of it broken out line by line, in writing, before anything starts. No deposit to get a number. Try the cost calculator for a first figure, then we come out and measure.
Frequently Asked Questions
Common questions about Dunthorpe Remodeling in Dunthorpe, Oregon.
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