OneBuild

About OneBuild

OneBuild is a design-led build coordination firm serving the Hudson Valley. Founded in 2025 by Spenser McCoy, the company was built around a straightforward idea: that design and construction should work together to make the process of adding space to a home clearer, more manageable, and less stressful for homeowners. McCoy's background in architectural training shapes how OneBuild approaches every project — from the first conversation to the final inspection.

OneBuild manages the full scope of an ADU project under one roof. That includes feasibility assessment, permitting, design coordination, prefab selection, and on-site installation. Their focus is on accessory dwelling units — commonly referred to as ADUs — including detached ADU structures, backyard cottages, in-law suites, and granny flats. For properties where a standard prefab model doesn't fit, they also offer custom design services through an architect-led process.

How the OneBuild Process Works

OneBuild uses a structured, step-by-step process designed to reduce the guesswork that often derails ADU projects before construction even begins.

1. Discovery Call — A 30-minute conversation to understand the homeowner's property, goals, and timeline. OneBuild provides an honest assessment of what path makes sense before any money is spent.
2. Feasibility Study — A written, site-specific report covering zoning, setbacks, utility access, septic or well conditions, and site constraints. The report outlines what is buildable, what it will cost, and what the timeline looks like.
3. Select a Direction — Based on the feasibility study, OneBuild suggests the most suitable path forward. The analysis is provided; the homeowner makes the final call.
4. Project Kickoff — Design development begins and the permitting process is managed with the local building department. Timelines vary by municipality.
5. Factory Assembly — The ADU unit is built off-site in a controlled factory environment, which typically results in faster production and tighter quality control compared to traditional site-built construction.
6. Site Preparation — While the unit is being manufactured, the foundation, utilities, and site access are prepared.
7. Delivery and Installation — The completed unit is delivered and installed on-site. OneBuild coordinates the installation and manages final inspections.
8. Final Touches — A final walkthrough ensures everything is in order before the homeowner receives their keys.

OneBuild works with prefab ADU manufacturers and evaluates models based on site conditions, local code requirements, and budget. Not every prefab product is approved in every municipality, and their team is familiar with those distinctions across the Hudson Valley region.

Services Offered by OneBuild

OneBuild offers a range of services that cover the full lifecycle of an ADU build:

1. Feasibility & Design — Every project begins with a property-specific feasibility study covering zoning, setbacks, utilities, grading, and budget alignment.
2. Permitting & Project Management — OneBuild handles permitting, approvals, and coordination with local building departments, keeping projects compliant and on schedule.
3. Transparent Pricing — Prefab ADU options are evaluated and presented with clear cost information. Units are installed by licensed contractors.
4. ROI Calculation — Upon request, OneBuild projects rental income potential, value growth, and payback periods based on ADU size, local market rates, and financing options.
5. Financing Assistance — OneBuild educates clients on ADU-friendly financing options, including home equity products, state programs, construction loans, and access to preferred lenders through their partner network.
6. Custom Builds — For properties or programs that don't fit a standard prefab model, OneBuild offers custom design services through their architect-led process.

On the financing side, OneBuild helps homeowners navigate local and state ADU programs in New York, home equity loans, cash-out refinancing, and partner financing options. They connect clients with trusted lenders and provide project cost estimates and ROI projections to support loan applications.

OneBuild positions itself as a single point of accountability throughout the entire process — from the initial feasibility conversation through to final installation. Their stated goal is to remove the confusion and hidden costs that often accompany ADU construction, delivering a clear and consistent process for homeowners in the Hudson Valley looking to add functional, lasting space to their property.