Home Addition Contractors & Accessory Dwelling Unit Builders

Your home should evolve with your family’s changing needs. Whether you’re looking to create additional living space for aging parents, provide privacy for adult children, accommodate long-term guests, or add rental income potential, a custom home addition or accessory dwelling unit (ADU) offers a practical solution without the need to relocate.

As experienced home addition contractors and accessory dwelling unit builders, we design and build everything from attached home additions and in-law suites to detached backyard cottages and granny flats. Our team works closely with you to evaluate your property, navigate local zoning and permitting requirements, and design a space that complements your home while meeting your long-term goals. From the initial concept through construction, we’re committed to making the process straightforward, personalized, and built around your vision.

Contact OSR today to make your home addition dreams a reality!

Your Home Addition Options

Attached Home Additions

Expand your existing home with additional living space that seamlessly integrates with your current layout and architecture.

Popular projects include:

In-law suites
Primary suite additions
Expanded living areas
Home offices
Multi-generational living spaces

Accessory Dwelling Units (ADUs)

As an experienced accessory dwelling unit builder, OSR designs and constructs fully independent living spaces located on the same property as your primary residence. Every ADU unit includes a kitchen, bathroom, sleeping area, and living space.

Common ADU styles include:

Detached backyard cottages
Granny flats
Guest houses
Garage apartments
Backyard homes

Attic, Basement & Garage Conversions

Transform underutilized areas of your home into comfortable, code-compliant living spaces without expanding your home’s footprint.

Conversion projects often include:

In-law suites
Rental units
Guest houses
Home offices
Recreation spaces

Ready to get started? Contact OSR, Your Local ADU Builder & Home Addition Contractor Today!

Your Home Addition Options

Attached Home Additions

Expand your existing home with additional living space that seamlessly integrates with your current layout and architecture.

Popular projects include:

In-law suites
Primary suite additions
Expanded living areas
Home offices
Multi-generational living spaces

Accessory Dwelling Units (ADUs)

As an experienced accessory dwelling unit builder, OSR designs and constructs fully independent living spaces located on the same property as your primary residence. Every ADU unit includes a kitchen, bathroom, sleeping area, and living space.

Common ADU styles include:

Detached backyard cottages
Granny flats
Guest houses
Garage apartments
Backyard homes

Attic, Basement & Garage Conversions

Transform underutilized areas of your home into comfortable, code-compliant living spaces without expanding your home’s footprint.

Conversion projects often include:

In-law suites
Rental units
Guest houses
Home offices
Recreation spaces

Ready to get started? Contact OSR, Your Local ADU Builder & Home Addition Contractor Today!

Why Choose OSR as your Home Addition Contractor or ADU Builder?

Local Zoning & Permitting Expertise

Building an ADU involves more than construction. Our team understands municipal zoning regulations, setback requirements, lot coverage limitations, and local permitting requirements to help keep your project moving forward.

Smart Space Planning

Small spaces require thoughtful design. We create efficient layouts that maximize comfort, storage, functionality, and livability.

Complete Utility Integration

Unlike traditional home additions, ADUs require dedicated plumbing, electrical, HVAC, and utility connections. Our team manages every aspect of the installation process from start to finish.

Construction Designed Around Your Family

Most ADU and home addition projects happen while homeowners continue living on-site. We prioritize organization, communication, and minimizing disruption throughout construction.

Design-Build Simplicity

From initial concepts and planning through permits and construction, we provide a streamlined process with a single point of contact from beginning to end.
In Law Suite - Granny Flat - ADU Contractor | OSR Builders
In Law Suite - Granny Flat - ADU Contractor | OSR Builders

Why Choose OSR as your Home Addition Contractor or ADU Builder?

Local Zoning & Permitting Expertise

Building an ADU involves more than construction. Our team understands municipal zoning regulations, setback requirements, lot coverage limitations, and local permitting requirements to help keep your project moving forward.

Smart Space Planning

Small spaces require thoughtful design. We create efficient layouts that maximize comfort, storage, functionality, and livability.

Complete Utility Integration

Unlike traditional home additions, ADUs require dedicated plumbing, electrical, HVAC, and utility connections. Our team manages every aspect of the installation process from start to finish.

Construction Designed Around Your Family

Most ADU and home addition projects happen while homeowners continue living on-site. We prioritize organization, communication, and minimizing disruption throughout construction.

Design-Build Simplicity

From initial concepts and planning through permits and construction, we provide a streamlined process with a single point of contact from beginning to end.
ADU Contractor - Accessory Dwelling Unit Contractor | OSR Builders

Frequently Asked Questions About Home Additions & ADUs

What is the difference between a home addition and an ADU?

A home addition expands your existing home and typically shares living spaces with the primary residence. An ADU is a separate, self-contained living space with its own kitchen, bathroom, and sleeping area.

What is an ADU?

An ADU, or Accessory Dwelling Unit, is a secondary housing unit built on the same property as a primary residence. ADUs are commonly called in-law suites, granny flats, backyard cottages, guest houses, or garage apartments.

What are the benefits of building an ADU?
  • Increase your home’s usable square footage
  • Create space for multi-generational living
  • Avoid the costs and stress of moving
  • Add long-term property value
  • Generate potential rental income
  • Keep aging family members close while maintaining privacy
  • Adapt your home to changing lifestyle needs
Can I build an in-law suite on my property?

In many municipalities, yes. Local zoning regulations determine whether attached or detached in-law suites are permitted. Our team can evaluate your property and guide you through the approval process.

Are granny flats and ADUs the same thing?

Yes. “Granny flat” is simply another common term for an Accessory Dwelling Unit.

Can an ADU be attached to my existing home?

Absolutely. Attached ADUs share at least one wall with the main residence while still functioning as independent living spaces.

Can I convert my garage into an ADU?

Many homeowners choose to convert attached or detached garages into fully functional ADUs, in-law suites, or rental units.

Does an ADU increase property value?

In most cases, yes. Additional living space and multi-generational housing options often make properties more attractive to future buyers.

How long does a home addition project take?

Project timelines vary based on size, complexity, permitting requirements, and site conditions. During your consultation, we provide a detailed project schedule based on your specific goals.

Ready to Expand Your Home?

Whether you’re planning an attached home addition, detached backyard cottage, in-law suite, or custom accessory dwelling unit, OSR can help you create a space that fits your family’s needs today and for years to come.

OSR Builders offers Home Addition & ADU Services in Chester and Montgomery Counties including Collegeville, Phoenixville, Spring City, Royersford, King of Prussia, Main Line, Malvern, Paoli and the surrounding areas.

Schedule a consultation to discuss your ADU or home addition ideas and explore the possibilities for your property today!