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. Initial consultations and estimates are always free. Reach out and we'll get back to you within one business day.
How long does a typical project take?
It depends on the size, scope, design complexity, permit process, and material availability. Smaller remodels may take only a few weeks, while larger custom homes or commercial projects can take several months. We use a critical path scheduling approach that allows us to complete projects up to 10× faster than the industry average without compromising quality. Before construction begins, we provide a projected timeline and keep clients informed throughout every phase.
How do you price a project?
Pricing is based on the size and scope of the project, design complexity, materials, site conditions, engineering requirements, and overall timeline. We provide a detailed, transparent estimate tailored to your goals and budget — and work closely with you throughout planning to maximize value and avoid unexpected costs.
Do you require a deposit?
Yes, in some cases we do require a deposit, depending on the size and nature of the project. However, our typical process is progress-based billing, where clients are billed as each phase or scope of work is completed.
At De Marco Builders, we believe in delivering results first before requesting payment whenever possible. This approach reflects our confidence in the quality of our work while also giving our clients greater peace of mind throughout the construction process. Any required deposits or payment schedules are discussed clearly and agreed upon before the project begins.
What happens if costs change during the project?
Project costs typically remain consistent with the original estimate unless you request changes to the scope of work, or there are significant shifts in material pricing due to market conditions beyond our control. Any changes are communicated clearly and promptly before we proceed, and documented through a written change order outlining the updated scope, pricing, and schedule — so you approve everything before additional work begins.
Can you work within a specific budget?
Yes. At De Marco Builders, we work closely with our clients to understand their budget goals and priorities from the beginning of the project. Our team helps guide design choices, material selections, and construction options to maximize value while maintaining quality craftsmanship.
Through careful planning and transparent communication, we strive to create solutions that align with both the client’s vision and budget without compromising the overall integrity and functionality of the project.
Are you licensed, bonded, and insured?
Yes. De Marco Builders is fully licensed, bonded, and insured. We are committed to maintaining professional standards, quality workmanship, and compliance with all applicable building regulations and safety requirements, giving our clients confidence and peace of mind throughout the construction process.
How do you handle unexpected issues that come up mid-project?
If unexpected issues arise during the project, we address them promptly and communicate with the client right away. However, we rarely experience major unexpected issues because we carefully plan and manage each project to help prevent unnecessary problems before they occur.
Our team works to find practical and cost-effective solutions while minimizing delays and keeping the project moving efficiently. Any necessary changes are discussed and approved before additional work proceeds.
How often will I receive updates?
Clients receive regular updates throughout the project, including progress, scheduling, and any important developments. We believe clear and consistent communication is essential to keeping projects running smoothly and ensuring our clients stay informed every step of the way.
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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