A Custom Casita: Multi-Generational Living in Gibsonia, PA
Prime1 Builders took on a distinctive project in Gibsonia, located in the North Hills area of Pittsburgh, where a couple relocating from the West Coast needed a practical solution for multi-generational living. Their goal was to bring the husband's mother — living in Texas at the time — closer to the family on a full-time basis, while still maintaining genuinely separate living spaces for both households.
The design team at Prime1 Builders first explored the possibility of a traditional home addition, but that approach consistently fell short of delivering the level of separation and independence both parties were looking for. The conversation then shifted toward building an Accessory Dwelling Unit (ADU) at the rear of the existing property.
Zoning regulations presented an early challenge. The 1+-acre lot did not permit a fully detached dwelling, but the code did allow for a connected structure. Prime1 Builders developed a solution: linking the new unit to the existing home via a covered concrete walkway, tied into the sitting porch adjacent to the kitchen. The rooflines were blended to create a cohesive appearance, and the walkway was constructed on a full foundation — allowing for future enclosure if desired. The space beneath the walkway was also used to run mechanical connections, including water, sewer, and natural gas lines.
The mother, who had Mexican heritage, referred to her new home as her "Casita" — her little house — a name that stuck throughout the project. This in-law suite builder project became a meaningful and personal build for everyone involved.
Inside the Casita: Layout and Features
Prime1 Builders designed the Casita with an open floor plan that makes efficient use of the available space. The interior includes:
- A great room with an open layout
- A kitchen with room for a small breakfast table and a dining area
- A covered porch accessible through a sliding glass door off the dining room
- A main bedroom with walk-in closets
- A second bedroom currently used as a home office
- One full bathroom
- A built-in entry bench with storage and coat hooks
- A utility room with space for a dedicated washer and dryer
Given the spatial constraints of the project, the team made deliberate choices to maximize functionality without overextending the footprint. All utilities for this accessory dwelling unit were extended from the existing house in compliance with local zoning requirements. The existing home's electrical service was upgraded to 400 amps, with a 200-amp service run to the new Casita.
Exterior Finish and Recognition
On the exterior, Prime1 Builders matched the new structure to the existing home with careful attention to detail — including matching siding type and color, white trim, and identical shingles. The result is a seamless appearance that makes the ADU look as though it was always part of the original house.
This granny flat builder project represents a practical middle ground: not a simple addition, and not a fully detached structure, but a well-considered solution that gave both households their own space while keeping the family close. The project was recognized with a 2023 House Excellence Award from the Building Association of Metro Pittsburgh.