ADUs & Home Additions · Portland, OR
More Space Same Address.
Whether you're adding a rental unit, accommodating family, or simply need more room — De Marco Builders delivers ADUs and home additions that are designed well, built to last, and completed on time. Free estimates, transparent pricing, no surprises.
Expanding what's possible
A Smarter Way To Grow.
Moving is expensive, disruptive, and not always necessary. In many cases, the right addition or accessory dwelling unit can give you exactly what you need — more living space, a source of rental income, or a comfortable place for family — without leaving the neighborhood you've chosen.
ADUs and additions are also one of the most financially sound decisions a homeowner can make. A well-designed, permitted addition increases the value of your property while delivering immediate functional benefits — whether that's additional living space, a dedicated rental unit, or a private space for family members. It is an investment that works for you now and pays dividends when it matters most.
THE Built To Belong
An Addition That Looks Like It Was Always There.
The most successful ADUs and additions are the ones you can't tell were added later. That requires more than good finishes — it requires careful attention to structural integration, material matching, roofline continuity, and the kind of design decisions that ensure the new space feels like a natural extension of the existing home rather than something attached to it as an afterthought.
A well-planned ADU or addition accounts for zoning requirements, structural considerations, utility connections, and long-term functionality from the outset. Projects that are designed with that level of care are the ones that get built efficiently, pass inspection without issue, and continue to perform well for years after completion.
THE PROCESS
What to Expect.
An ADU or addition project moves through several distinct phases — site assessment, design development, permitting, and construction — each one dependent on the decisions made in the phase before it. The permitting phase in particular requires careful attention, as requirements vary by property type, location, and project scope. A thorough pre-construction process is what prevents those variables from becoming obstacles once work is underway.
Construction on an ADU or addition requires the same level of coordination as any significant building project — structural work, mechanical, electrical, plumbing, and finishes all need to be sequenced correctly and executed to a consistent standard. Clients should expect clear communication at every phase, written documentation of any changes before work proceeds, and a finished result that has been inspected, permitted, and built to last.
WHY DEMARCO
Why Portland Clients Choose Us.
Portland's longest-serving custom builder
In business since 1996, we know Portland's neighborhoods, soils, permits, and inspectors better than anyone.
Fixed price, fixed schedule
What we quote is what you pay. The date we give you is the date we hit. No surprise change orders, no budget creep, no exceptions — not once in 30 years of Portland construction.
One team from start to finish
Design, permits, construction — same crew, same point of contact, from the first site walk to the day we hand you the keys. No gaps in accountability, no finger-pointing when something needs to be fixed.
Award-winning craftsmanship
Recognized by Portland Monthly and the NW Natural Street of Dreams.
Family-owned since day one
Same owners, same values, nearly three decades running. You work with the people whose name is on the door.
Serving all of Portland Metro
From Lake Oswego and West Linn to Beaverton, Tigard, and every Portland neighborhood in between.
FAQ
Common Questions.
Can't find the answer you're looking for? Reach out and we'll get back to you within one business day.
Do you offer free estimates?
Yes
How long does a typical project take?
It depends on the size, scope, design complexity and permit process.
Typical project timelines include:
- ADUs: 45–60 days
- Home Additions: 45–90 days
- Remodels: 30–90 days
- Custom Homes: 90–160 days
- Commercial Projects: 90–160 days
How do you price a project?
Every proposal from De Marco Builders provides complete cost transparency. Our estimates clearly show the construction costs, company overhead, profit, and total project cost so clients fully understand where every dollar is allocated.
Do you require a deposit?
No. Never. We do not require an upfront deposit. The first payment is due only after a portion of the contracted work has been completed.
What happens if costs change during the project?
We guarantee the contract price through project completion unless the homeowner requests additional work beyond the original scope or unforeseen structural conditions are discovered that were not visible during the initial evaluation.
Can you work within a specific budget?
Absolutely. De Marco Builders is a budget-driven builder. We work within the client’s established budget throughout the design, engineering, permitting, and construction phases. We utilize value-engineering principles to maximize quality while maintaining budget goals.
Are you licensed, bonded, and insured?
Yes. De Marco Builders is fully licensed, bonded, and insured. We maintain all required certifications and operate in full compliance with state regulations.
How do you handle unexpected issues that come up mid-project?
Unexpected issues are rare because of our extensive experience and thorough planning process. If an unforeseen issue does arise, it is addressed immediately, typically within 24 hours. We resolve issues in a code-compliant manner while protecting the project schedule.
How often will I receive updates?
Communication is one of our highest priorities. Once a client signs a contract, we maintain frequent communication throughout design, engineering, permitting, and construction. Clients receive regular progress updates, photos, and end-of-day reports so they remain informed from start to finish.
Our Projects
Recent Work
Design-Build Custom Home Portland | De Marco Builders
See how De Marco Builders transformed a 900 sq ft 1946 bungalow into a 2,400 sq ft custom home in just 120 days. Portland’s design-build general contractor.
Whole Home Remodel in NE Portland | De Marco Builders
Studs-out renovation: new electrical, plumbing, HVAC, two primary suites, relocated kitchen, and white oak finishes — completed in 120 days. Portland remodel contractor.
Backyard Cottage ADU Built in 89 Days | De Marco Builders
One of Portland’s most efficient ADU builds: an 800 sq ft craftsman backyard cottage, fully permitted and completed in just 89 days.
Ready to Build Something
You'll Love?
Get a free consultation with our team — no commitment, just a conversation about what's possible.
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