Accessory Dwelling Units and Guest Houses: What Homeowners Should Know
The concept of a carriage house — a detached structure on a residential property — has roots going back centuries. Originally built as two-story structures to house horses on the lower level and a caretaker above, these buildings have evolved considerably. Today, the modern equivalent is commonly referred to as an accessory dwelling unit (ADU), a secondary housing unit situated on a single-family residential lot. Mosby Building Arts works with homeowners looking to build or renovate these types of structures.
If an ADU does not already exist on a property, adding one can serve a number of practical purposes. A detached ADU or guest house can function as living quarters for aging parents, adult children, visiting family and friends, or live-in caretakers. It can also be used as a rental unit, which may generate additional income. As a secondary benefit, a well-designed guest house can contribute to the overall value of the property.
That said, it is worth noting that owning and maintaining a guest house comes with added responsibilities and costs — including utilities, landscaping, and general upkeep. Thorough planning before starting a project of this scale is strongly advisable.
Design Considerations for a Guest House or ADU
The intended use of the space should guide the design process from the start. A typical guest house includes a kitchenette, bathroom, bedroom, and a small living area. However, the specific needs of the occupants will shape how the space is ultimately configured:
- If aging parents will be residing there, accessible design features such as wider doorways and adapted bathrooms may be necessary.
- If the space is intended for a live-in caretaker, it should function as a fully equipped residence, scaled appropriately.
- If the primary use is personal — such as a home office, children's playroom, or teen hangout space — the layout and finishes can reflect that more flexible purpose.
Budget, available square footage, and local zoning regulations will all play a role in determining the scope and complexity of the project.
A Recent Guest House Remodel by Mosby Building Arts
Mosby Building Arts recently completed a full remodel of an existing guest house for homeowners who wanted to update the space for visiting relatives and friends. The original structure was dark, dated, and no longer functional for its intended purpose.
Working closely with the homeowners, Mosby's design team developed a modern farmhouse aesthetic that balanced style with practicality. On the exterior, the team — operating under the Exteriors by Mosby division — updated the façade to better complement the main home. This included new siding, windows, doors, and exterior lighting.
Inside, the kitchen was redesigned with distinctive blue cabinetry and personalized accessories to give the space a defined character. New engineered hardwood flooring was installed throughout to coordinate with the solid wood surfaces found in the main residence. The bathroom received a classic treatment, featuring a black and white color palette with mini hexagon tile, white quartz countertops, and a black vanity.
The completed project reflects Mosby Building Arts' approach to guest house and ADU renovation work — balancing the homeowner's vision with functional design choices suited to how the space will actually be used.