Turn Unused Yard Space Into Housing

Accessory dwelling unit construction for Portland properties, from design through occupancy approval.

Your backyard sits mostly empty, or your garage holds clutter instead of cars, and you've considered converting that space into something more useful. An accessory dwelling unit gives you a standalone or attached residence that functions independently from your main home. In Portland, these units are commonly used for rental income, housing family members, or creating a private home office with full amenities. The construction process involves zoning review, permit approval, and building to Maine's energy and structural standards.

Sparrow Remodeling offers three ADU types: detached units built from the ground up, attached additions that share a wall with your main house, and garage conversions that reuse your existing structure. Each option meets Portland zoning requirements and is designed for year-round use in Maine weather. We handle the permit process, coordinate inspections, and build to the specifications you approve. Pricing depends on size, finishes, and site conditions, and we provide a detailed estimate before any work begins.

If you want to add a livable unit to your Portland property, get in touch to review your lot and talk through what type of ADU fits your needs.

Design Choices That Affect Function and Cost

We begin with a site visit to your Portland property to measure setbacks, check utility access, and identify any grading or drainage concerns. You choose between detached, attached, or garage-conversion layouts based on your lot size and budget. Detached units offer the most privacy and flexibility but require full foundation and utility work. Attached units save on shared walls and heating costs but limit placement options. Garage conversions reuse your existing slab and roof, cutting both material and labor expenses.

Once built, you have a separate living space with its own entrance, kitchen, bathroom, and climate control. The walls are insulated to meet Maine energy codes, windows are rated for winter performance, and all mechanical systems are installed and inspected. The unit increases your property's appraised value and gives you flexible housing options without moving or buying a second property.

We use local electricians, plumbers, and HVAC contractors who know Portland building codes and work efficiently through Maine winters. All lumber and exterior materials are selected for durability in freeze-thaw cycles and coastal moisture. Sparrow Remodeling does not provide financing or property appraisal services, but we do supply all documentation needed for permits, insurance, and resale records.

What Homeowners Usually Want to Know

Before starting an ADU project, Portland homeowners typically have questions about zoning, cost, and what the build process actually looks like from start to finish.

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What's the difference between a detached ADU and a garage conversion?
A detached ADU is built from scratch on a new foundation, giving you full control over layout and location. A garage conversion reuses your existing structure, saving time and money but limiting design flexibility.
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How much does an accessory dwelling unit cost to build?
Costs vary based on size, finishes, and site conditions, but most ADUs in Portland range from mid-five to low-six figures. We provide a detailed estimate after reviewing your lot and design preferences.
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What zoning rules apply to ADUs in Portland?
Portland typically allows one ADU per residential lot, with size limits based on your primary home's square footage and setback requirements from property lines. We confirm zoning compliance before submitting permit applications.
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When is an ADU ready to occupy or rent?
The unit is ready once it passes final inspection from the city, which covers electrical, plumbing, egress, and energy performance. You receive a certificate of occupancy, and the space is legally habitable that day.
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Why build an ADU instead of adding onto the main house?
An ADU offers a separate entrance, utilities, and living space, which works better for renters or family members who want privacy. Main house additions share systems and access, which can feel crowded depending on your household.

Sparrow Remodeling designs and builds accessory dwelling units across Portland, working within your lot's constraints and your budget. Contact us to schedule a site visit and discuss what type of ADU makes sense for your property.