Accessory Structures
Explore Versatile Accessory Structures to Maximize Your Property’s Potential
From stylish detached garage apartments and cozy backyard guest cottages to modern pool houses, gazebos, workshops, and she sheds, this curated collection of accessory structure plans offers smart, flexible solutions for expanding your living space and boosting your property’s value.
Garage apartments continue to grow in popularity, serving as ideal solutions for multi-generational living, aging in place, or generating passive rental income. These efficient designs often take advantage of existing foundations and roofs, making them a cost-effective way to add livable square footage with a second-story layout.
Modern pool house designs are trending for 2025, evolving into luxurious outdoor living spaces that include full kitchens, indoor/outdoor fireplaces, integrated smart home features, bathrooms, changing rooms, and entertainment zones. These versatile structures seamlessly extend your home's functionality and support year-round entertaining.
Standalone workshops, hobby studios, and backyard sheds are also being reimagined in 2025 as creative spaces—ideal for remote work, art, fitness, or even small business operations. Whether you need extra storage or a serene retreat, these flexible floor plans are designed to reflect your lifestyle.
Pool houses have also seen a resurgence as more homeowners look for ways to maximize space on their property for outdoor living. Today many of these plans feature fully equipped kitchens, fireplaces, enclosed TVs, bathrooms and changing rooms.
At The House Plan Company, our accessory structure plans are customizable to suit your lot, style, and specific needs. Whether you’re adding a granny flat, creating a tiny guest house, or building a multi-use garden structure, we offer professionally designed plans that make the most of your available space.
Browse our full collection of accessory building plans to find the perfect addition to your property. With the right design, even a compact footprint can transform into a high-functioning space that adds comfort, convenience, and long-term value.
Contact our Customer Service team for help finding the perfect accessory structure, Contact Us.
Discover the featured plan: Alderwood 37753
Accessory Structure Plans FAQ
What is an accessory structure?
At The House Plan Company, we offer a wide selection of accessory structure plans to complement your primary residence. Whether you're looking for a garage with a loft apartment, a backyard office, or a multi-purpose shed, our plans are crafted by experienced designers to meet your needs.
Adding an accessory structure is a smart and flexible way to maximize your property’s functionality, value, and curb appeal. Be sure to check with your local building department for zoning regulations, size limits, and permit requirements before construction.
Explore our collection of detached garage plans, ADU designs, and backyard building plans to find the perfect match for your lifestyle.
How do I search for an accessory structure?
- Tip 1: Search FiltersStarting with a plan collection is a great place to start and beginning with our Accessory Structures collection will help you focus on these auxiliary designs. From here Search Filters will help you further zero in on that perfect plan. Applying a structure type filter will add another layer to help you find that perfect pool house plan without having to filter through shops or garages.
- • Tip 2: Search outside of a CollectionIf you are looking for a plan that offers multiple features or functions, then starting with an open search outside one of our curated collections may be the best starting point. For instance Accessory Dwelling Units come in a variety of configurations.
- Configuration 1: Detached ADUA detached Accessory Dwelling Unit offers opportunities for rental income or guest accommodations that offer maximum privacy. To search for the perfect detached ADU plan, try searching for Single Family structures in our Accessory Structure Collection or Tiny House Plans.
- Configuration 2: Garage ApartmentsGarage Apartments offer the ultimate solution for enhancing your property, increasing vehicle storage or space for hobbies while also incorporating an ADU. The perfect Garage Apartment may be found across a handful of collections. Start by diving into our Garage, Garages w/Living, Carports collection. Under the search filters apply the Garage with Living option to see stunning designs that masterfully blend the functions of a garage with attached apartments.
- Configuration 3: Single Family with Attached ADU or CastiasTo find an Accessory Dwelling Unit design that blends a primary single-family residence with a Casita or attached ADU, start with any of our single-family collections or our duplex/multifamily collection.
While our Accessory Structure collection is an ideal place to start your search for a plan that will enhance your property, jumping outside the collection can open up design options.
Still need help finding the perfect plan for your project? Reach out to our customer service team via email, chat, or phone! They will listen to your design goals and can provide search recommendations or plans to review.
How much will it cost to build an accessory structure?
According to the 2024 National Association of Home Builders (NAHB) construction cost data, the average cost to build residential space is approximately $153 per square foot. However, accessory structures tend to vary more widely:
- Basic storage sheds or simple carports: $50–$100 per square foot
- Detached garages or workshops: $100–$150 per square foot
- Finished ADUs or guest houses with kitchens and bathrooms: $200–$400+ per square foot
- Foundation type (slab, crawlspace, or pier)
- Utility hookups (plumbing, electrical, HVAC)
- Insulation and energy code requirements
- Local labor rates and permit fees
Additional cost factors include:
At The House Plan Company, our collection of accessory structure plans ranges from simple and affordable to fully finished living spaces. Many of our designs can be customized to fit your budget and building goals.
To get a more accurate estimate, we recommend choosing a plan, purchasing a plan package, and consulting with a local builder or contractor who can provide a detailed cost breakdown based on your region and specific site conditions. Not ready to commit to a plan? We have partnered with StartBuild to provide Cost to Build reports.
Explore our wide selection of garage plans, workshops, sheds, and ADUs to find the right accessory structure for your property and budget.
Can I customize an accessory structure?
Common customizations include:
- Changing the dimensions or footprint of the structure
- Adjusting rooflines, door and window placements
- Adding or removing living space, lofts, or storage areas
- Converting a garage into a guest suite or rental unit (ADU)
- Modifying the plan to meet local building codes and zoning requirements
Customizing your accessory structure ensures that it fits seamlessly with your existing home design, complies with local regulations, and serves your specific needs—whether it’s for extra parking, a hobby space, or a private retreat.
To get started, simply choose your favorite accessory structure plan and request a modification quote from the designer. We’re here to help you bring your vision to life with flexibility and expert guidance.
Is this plan suitable for converting to an ADU or Guest House?
Plans commonly adapted into ADUs or guest houses include:
- Detached garages with lofts or finished upper levels
- Workshops or studios with open floor plans
- Pool houses with plumbing-ready layouts
- Compact cottages and backyard cabins
When converting a plan to an ADU, you may need to incorporate key features such as:
- A full bathroom and kitchen
- Insulation and HVAC systems
- Windows and doors that meet egress requirements
- Utility hookups for water, sewer, and electricity
- Compliance with local ADU zoning laws and building codes
Our team at The House Plan Company can connect you with designers who offer modification services to help transform your chosen plan into a fully functional ADU or guest house. We recommend reviewing your local ADU regulations before starting the conversion process, as requirements vary by municipality.
Explore our growing collection of ADU-ready plans and let us help you find the perfect design for your property and lifestyle.
Will this accessory structure meet my local codes?
Factors that may affect code compliance include:
- Snow loads, wind zones, and seismic activity
- Zoning restrictions, such as height limits, setbacks, and maximum square footage
- Requirements for plumbing, electrical systems, or living space (especially for ADUs)
- Local mandates for energy efficiency and sustainability
To ensure your chosen garage, workshop, ADU, or backyard structure plan meets local requirements, we strongly recommend consulting with your local building department and having a licensed engineer or architect review the plans if needed. Many of our designers also offer modification services to help tailor the plans for regional code compliance.
At The House Plan Company, we’re committed to helping you build with confidence. Browse our collection of accessory structure plans and contact us to discuss customization options that fit your location and project goals.
Blog | Backyard Cottages Gain Popularity
Blog | Elevate Your Property with a Detached Garage
Trending Accessory Structure Plans
Discover the variety of accessory structure plans here!
Plan Details | Plan Image |
---|---|
Pool House Plan Steamboat Springs 82180
|
![]() |
Detached Workshop West Coy Workshop 23171
|
![]() |
Barn Plan 82931
|
![]() |
Hazel Detached Garage with Apartment 90605
|
![]() |
Juniper Two ADU 3005
|
![]() |
Looking for more great Accessory Structure plans? Explore the full collection here: Accessory Structure Plans
DISCOVER MORE FROM HPC
From in-depth articles about your favorite styles and trends to additional plans that you may be interested in. The House Plan Company is here to make the search for more — easy for you.
-
Design Collection
Garage Plans + Carports
Detached garages plans are a great way to add functionality to a property. The House Plan Company's collection of Garages + Carports feature designs that include living space and hobby rooms.
Explore Plans > -
Blog
Garage Apartments & Backyard Cottages Gain Popularity
Homeowners are seeking ways to add flexibility and value to their property with the addition of detached garage apartments or standalone backyard cottages.
Read More > -
Blog
Accessory Structures Offer Space and Value to Your Home
Detached garages with granny flats, backyard guest cottages, pool houses, gazebos, and standalone workshops and hobby rooms all have several things in common—they’re accessory building structures that can add much needed living space and value to a residential property.
Read More >